Umzch Sukhova on imported components. UMPs with a microcontroller control system. Full set of service nodes

Viktor Zhukovsky, Krasnoarmeysk Donetsk region.

UML BB-2010 is a new development from a widely known line of AMPs BB (high loyalty) [1; 2; five]. A number of technical solutions were influenced by the work of Ageev Si. .

The amplifier provides KR of about 0.001% at a frequency of 20 kHz with a pv \u003d 150 W on a load of 8 ohms, a low signal frequency band for -3 dB - 0 Hz ... 800 kHz, output voltage rate -100 V / μs, signal / noise ratio and signal / background -120 dB.

Thanks to the use of OE operating in lightweight mode, as well as the use of only cascades in the voltage amplifier with OK and OO, covered by deep local OOS, the UMRs BB is characterized by a high linearity even to coverage of the total OOS. In the very first high loyalty amplifier in 1985, decisions were applied, until we used only in the measuring technique: DEed current modes supported a separate service unit, to reduce the level of interface distortions covered by the overall reverse negative connection of the transition resistance of the contact group of the AC switching And the special node effectively compensates for the impact on these distortion of the resistance of the AC cables. The tradition has been preserved in the UMBC 2010, at the same time, the total OOS covers the resistance of the output FNC.

In the absolute majority of the designs of other UMPs, both professional and amateur, many of these solutions are still missing. At the same time, the high technical characteristics and audiophile advantages of the UMRs BB are achieved by simple circuitry solutions and a minimum of active elements. In fact, this is a relatively simple amplifier: one channel is not in a hurry can be assembled in a couple of days, and the setting is only in the installation of the required overpass current of the output transistors. Especially for novice radio amateurs developed a method of puezlovaya, sophisticated performance and adjustment testing, using which it is guaranteed to localize the places of possible errors and prevent their possible consequences before fully assembling UMP. All possible questions about this or similar amplifiers have detailed explanations, both on paper, and on the Internet.

At the inlet of the amplifier is provided with R1C1 with a cutoff frequency of 1.6 Hz, Fig. 1. But the efficiency of the modes stabilization device allows the amplifier to work with an input signal containing up to 400 mw of the constant component. Therefore, C1 is excluded that it realizes the eternal audio dream of the tract without capacitors © and significantly improves the sound of the amplifier.

Capacity C2 capacitor of the input R2C2 input PNHs is selected so that the frequency of the input FGC cutting into account the output resistance of the preamp of 500 Ohm -1 kΩ was in the range from 120 to 200 kHz. The R3R5C3 frequency correction chain of R3R5C3 is made on the DA1 input, which limits the bands of the harmonic and interference from the OOS circuit on the exit side of the UMR, a strip of 215 kHz in terms of -3 dB and increases the stability of the amplifier. This chain allows you to reduce the difference signal above the frequency of the circuit cutting and the empty overload of the voltage amplifier of high-frequency filming, interference and harmonics, eliminating the possibility of dynamic intermodulation distortion (TIM; DIM).

Next, the signal enters the input of a low-noise operational amplifier with field transistors at the input DA1. Many "complaints" to the UMRs BB are presented with opponents about the use of the OU input, allegedly worsening the sound quality and "squeezing virtual depth" of sound. In this regard, it is necessary to pay attention to some of the obvious features of the work of the OMA in the UMP.

Operational amplifiers of preliminary amplifiers, the monthly OU is forced to develop several volts of the output voltage. Since the gain of OU is small and ranges from 500 to 2.00 times by 20 kHz, this indicates their operation with a relatively large voltage of the difference signal - from several hundred microwaves on the LF to several millivolts by 20 kHz and a high probability of entering the input cascade of the OU intermodulation distortion. The output voltage of these OU is equal to the output voltage of the last cascade of the gain of the voltage, which is usually made according to the scheme with OE. The output voltage in several volts indicates the operation of this cascade with rather large input and output voltages, and as a result - making it distortion into the enhanced signal. The OU is loaded on the resistance of the circuit parallel to the included circuits of the OOS and the load, which is sometimes somewhat kiloma, which requires from the output repeater of the output current amplifier to several milliamperes. Therefore, changes in the current of the output repeater IC, the output cascades of which consume no more than 2 mA currents are quite significant, which also indicates that they make distortions into the increased signal. We see that the input cascade, the stress enhancement cascade and the OU output cascade can cause distortion.

But the circuitry of high loyalty amplifier due to the high amplification and the input resistance of the transistor part of the voltage amplifier provides very gentle working conditions of the DA1. Judge for yourself. Even in the nominal output voltage 50 in the UMR, the input differential Cascade of OU operates with difference signals with a voltage of 12 μV at 500 Hz frequencies to 500 μV at a frequency of 20 kHz. The ratio of high input transistors, made on field transistors, and meager voltage of the difference signal ensures high linearity of the signal amplification. OU output voltage does not exceed 300 mV. What indicates a small input voltage of the voltage gain with a common emitter from the operational amplifier - up to 60 μV - and linear mode of its operation. OU output cascade is in order to load about 100 kΩ from the VT2 database, alternating current is not more than 3 μA. Consequently, the OU's output cascade also works in extremely lightweight mode, almost idle. On the real musical voltage signal and currents most of the time an order of magnitude smaller than the values.

From the comparison of the voltages of the difference and output signals, as well as the load current, it can be seen that, in general, the operational amplifier in the UMRs BB operates hundreds of times more easy, and, it means both linear mode than the ISU mode of preamstressors and the pass-in-room CD-players that serve as sources The signal for the umzch with any depth of the OOS, and also at all without it. Consequently, the same OU will be made as part of the UMP BB much smaller distortion than in single inclusion.

Occasionally, the opinion is observed that the distortion cascade is ambiguously dependent on the input voltage. This is mistake. The dependence of the nonlinearity of the cascade from the input voltage can obey one or another law, but it is always unambiguous: an increase in this voltage never leads to a decrease in the injured distortions, but only to zoom.

It is known that the level of distortion products coming to this frequency is reduced in proportion to the depth of the negative feedback for this frequency. The idling coefficient, to the coverage of the OOS amplifier, is impossible to measure at low frequencies due to the smallness of the input signal. According to calculations developed before coverage, the strengthening of idling allows to achieve the depth of the EOS 104 dB at frequencies of up to 500 Hz. Measurements for frequencies, starting with 10 kHz, show that the depth of the EOS at a frequency of 10 kHz reaches 80 dB, at a frequency of 20 kHz - 72 dB, at a frequency of 50 kHz - 62 dB and 40 dB - at a frequency of 200 kHz. Figure 2 shows the amplitude-frequency characteristics of the UMR BB-2010 and, for comparison, similar to the complexity of the Umzch Leonid Zueva.

High strengthening to coverage of the EOS is the main feature of the circuitry of explosive amplifiers. Since the goal of all circular triggers is to achieve high linearity and greater gain to maintain deep OOS in the maximum wide frequency band, this means that the schemes of improving the parameters of amplifiers are exhausted by such structures. Further reduction in distortion can be provided only with constructive measures aimed at reducing the supply of a harmonic of the output cascade to the input chains, especially on the inverting input circuit, the amplification of which is maximum.

Another feature of the SCHA circuitry BB is the current control of the output stage of the voltage amplifier. The input OU controls the voltage-current conversion cascade, made with OK and OR, and the resulting current is deducted from the cascade of the cascade current, made according to the scheme with OB.

The use of a linearizing resistor R17 resistance to 1 kΩ in a differential Cascade VT1, VT2 on transistors of different structures With serial power increases the linearity of conversion of the output voltage of the DA1 output voltage in the VT2 collector current by creating a local OOS with a depth of 40 dB. This can be seen from the comparison of the amount of emitters of VT1, VT2 emitters - about 5 ohms - with the resistance R17, or the sum of thermal stresses VT1, VT2 is about 50 mV - with a drop of voltage at the resistance R17, which makes 5.2 - 5.6 V .

In constructed under the scheme engineering of amplifiers, there is a sharp, 40 dB for a decade of frequency, recession of the gain over the frequency of 13 ... 16 kHz. An error signal, which is a distortion products, at frequencies above 20 kHz for two or three, less than the useful beep. This makes it possible to convert the linearity of the VT1, VT2 dyphcascade in these frequencies to increase the gain of the transistor part of UN. Due to minor changes in the current of Diffscad VT1, VT2 when the weak signals enhance its linearity with a decrease in the depth of the local OOS, it does not deteriorate significantly, but the operation of the OU DA1, the linearity of the entire amplifier on these frequencies depends on these frequencies, as all voltages, Determining by an operating amplifier of distortion, starting from the difference signal to the output, decrease in proportion to winning in reinforcement at this frequency.

The phase correction chains in phase R18C13 and R19C16 were optimized in the simulator in order to reduce the difference voltage of the OU to the frequencies in several megahertz. It was possible to increase the gain of the UMD of the BB 2010 compared with the UMPs of BB-2008 at frequencies of the order of several hundred kilohertz. Gain in strengthening was 4 dB at a frequency of 200 kHz, 6 - 300 kHz, 8.6 - by 500 kHz, 10.5 dB - 800 kHz, 11 dB - for 1 MHz and from 10 to 12 dB - at frequencies above 2 MHz. This is seen from the results of the simulation, Fig. 3, where the lower curve refers to the ACH chain of the correction chain to lead the UMPs of BB-2008, and the upper-amount of BB 2010.

VD7 protects the emitter transition VT1 from the reverse voltage resulting from the flow of reloading currents C13, C16 in the limit mode of the output signal for the voltage and arising from this limit voltage at the highest speed at the OU DA1 output.

The output stage of the voltage amplifier is made on the VT3 transistor included according to the scheme with a common base, which eliminates the penetration of the signal from the output chains of the cascade in the input and increases its stability. Cascade with OB, loaded to the current generator on the transistor VT5 and the input resistance of the output stage, develops a high steady gain - to 13.000 ... 15.000 times. The resistance of the resistor R24 \u200b\u200bis twice as smaller resistance of the R26 resistor ensures the equality of resting current VT1, VT2 and VT3, VT5. R24, R26 provide local OCOs that reduce the effect of ERLI effect - change of P21E depending on the collector voltage and increase the original linearity of the amplifier by 40 dB and 46 dB, respectively. The power supply of UN is separate voltage, module 15s above the voltage of the output cascades, allows to eliminate the effect of quasi-suction of transistors VT3, VT5, manifested in a decrease in P21E when a voltage reducing collector-base is below 7 V.

Three-kalid output repeater is assembled on bipolar transistors and special comments does not require. Do not try to fight entropy ©, saving on the current of the rest of the output transistors. It should not be less than 250 mA; In the author - 320 mA.

Before the activation relay is triggered, the amplifier is covered by OOS1 implemented by the inclusion of the R6R4 divider. The accuracy of compliance with R6 resistance and the consistency of these resistances in different channels is not significant, but it is important to preserve the stability of the amplifier that the resistance R6 is not much lower than the amount of resistance R8 and R70. The OOS1 relay response is disabled and the OOS2 circuit formed by R8R70C44 and R4 is entered into operation, and the contact group K1.1, where R70C44 eliminates the R71L1 R72C47 output from the OUOS circuit at frequencies above 33 kHz. The frequency-dependent EOS R7C10 forms a decline in ACH UMP to the output FGH at a frequency of 800 kHz in terms of -3 dB and provides a margin in the depth of the OOS above this frequency. ACH decline on AC terminals above the frequency of 280 kHz in terms of -3 dB is provided by the joint action of R7C10 and the output FNC R71L1 -R72C47.

The resonant properties of loudspeakers lead to the radiation of the damping sound oscillations, the gods after the pulse exposure and generating their own voltage when the coils of the magnetic field loudspeaker in the magnetic system gap. The damping coefficient shows how large the amplitude of the diffuser oscillations and how fast they fade with the load of AC as a generator for the full resistance from the UMP. This coefficient is equal to the AC resistance ratio to the sum of the impact resistance of the UMP, the transition resistance of the contact group of the switching relay of the AU, the resistance is completed normally by the insufficient diameter of the inductance coil of the output FGH, transient resistance of the Cable Cables and the resistance of the AC cables of the AC.

In addition, the impedance of acoustic systems is non-linear. The flow of distorted currents on the wires of the AC cables creates a voltage drop with a large proportion of nonlinear distortion, also deductible from the undisputed output voltage of the amplifier. Therefore, the signal on the Clamps AC is distorted much more than at the exit of the urzch. These are the so-called interface distortion.

To reduce these distortions, compensation of all components of the total output resistance of the amplifier was applied. Owner's own output resistivity, together with the transition resistance of the contacts of the relay and the resistance of the wire of the inductance coil of the output FNC, is reduced by the action of deep overall OOS, taken from the right output L1. In addition, the connection of the right-hand R70 to the "hot" terminal AC can be easily arranged to compensate for the transition resistance of the Cable AC cable and resistance of one of the AC wires, without fearing the generation of UMPs due to phase shifts in the Wires covered.

The AC wire resistance compensation node is made in the form of an inverting amplifier with KY \u003d -2 to the DA2, R10, C4, R11 and R9. The input voltage for this amplifier is the voltage drop on the "cold" ("earth") of the AU wire. Since its resistance is the resistance of the "hot" wire of the AU cable, to compensate for the resistance of both wires, it is enough to double the voltage on the "cold" wire, invert it and through the R9 resistor with a resistance equal to the sum of the resistances of the R8 and R70 circuit of the OOS, to submit to the inverting input of OU DA1 . Then the output voltage of UMPs will increase by the amount of voltage drops on the wires of the AC, which is equivalent to the elimination of the effect of their resistance to the damping ratio and the level of interface distortion at the Clamps of the AU. Fall compensation on the resistance of the AC wires of the non-linear component of the anti-eads of loudspeakers is especially needed at the lower frequencies of the sound band. The voltage of the signal on the RF loudspeaker is limited to the resistor and condenser connected to it. Their complex resistance is much more resistance of cable wires, therefore, the compensation of this resistance to the RF is deprived of meaning. Based on this, the integrating circuit R11C4 limits the frequency band of the compensator with a value of 22 kHz.

Especially it should be noted: the resistance of the "hot" wire of the AC cable wire can be compensated by covered by its total IOS connecting the right-hand R70 with a special wire to the "hot" led terminal. In this case, it will take compensation only by the resistance of the "cold" wire AC and the coefficient of amplification of the wire resistance compensator must be reduced to the value of ku \u003d -1 by selecting the resistor resistance R10 equal to the resistor resistor R11.

The current protection node prevents damage to the output transistors with short circuits in the load. The current sensor serve resistors R53 - R56 and R57 - R60, which is quite enough. The flow of the amplifier's output currents through these resistors creates a voltage drop, which is applied to the R41R42 divider. The voltage with the value of the threshold opens the VT10 transistor, and its collector current opens the VT8 VT8VT9 trigger cell. This cell passes into a stable state with open transistors and shunt the HL1VD8 chain, reducing the current through the stabilion to zero and locking the VT3. The C21 discharge of the VT3 base current can take several milliseconds. After the trigger cell is triggered, the voltage on the bottom of the C23, charged with the voltage on the HL1 LED to 1.6 V, rises from the level -7.2 V from the positive bus of the power supply of UN to level -1.2 b 1 voltage on the top folding of this capacitor also rises On 5 V. C21 quickly discharged through the R30 resistor on C23, the VT3 transistor is locked. Meanwhile, VT6 opens and through R33, R36 opens VT7. VT7 shunt stabilodron VD9, discharges through R31 C22 capacitor and locks the VT5 transistor. Without receiving offset voltages, the output cascade transistors are also locked.

Restoring the original status of the trigger and the activation of the UMR is performed by pressing the SA1 button "Reset protection". C27 is charged with a current collector VT9 and shunt the VT8 base chain by locking the trigger cell. If by this moment the emergency situation is eliminated and the VT10 locked, the cell goes into a state with steadily closed transistors. VT6, VT7 are closed, on the VT3, VT5 database, the reference voltage and the amplifier enters the operating mode. If the short circuit in the load of the UMR continues, the protection is triggered again, even if the C27 capacitor is connected to SA1. Protection works so effectively that during work on configuring the correction, the amplifier was de-energized several times for small repairs ... with a touch to non-inverter. The resulting self-excitation led to an increase in the current of the output transistors, and the protection turned off the amplifier. Although this coarse method cannot be offered, but thanks to current protection He did not harm the output transistors.

Work compensator for the resistance of the Cable AU.

The effectiveness of the work compensator of BB-2008 was checked by the old audiophile method, hearing, switching the compensator input between the compensating wire and the overall wire of the amplifier. Improvement of sound was clearly noticeable, and the future owner could not have failed to get an amplifier, so the measurements of the effect of the compensator was not conducted. The advantages of the scheme with the "Caboratory" were so obvious that the "compensator + integrator" configuration was accepted as a standard unit for installation in all the enhancer developed.

Surprisingly, how many unnecessary disputes around the utility / unnecessary compensation of the resistance of cables broke out on the Internet. As usual, they especially insisted on listening to the nonlinear signal. Those who are extremely simple, the cable cell seemed difficult and incomprehensible, the costs of it are exorbitant, and the installation - time-consuming ©. Even the proposals were expressed that, since such a lot of money was spent on the amplifier itself, then the sin save on the holy, and you need to go the best, glamorous way, how all civilized humanity goes and ... acquire normal, human © superdaded cables from precious metals. To my great surprise, oils in the fire poured statements by very respected specialists about the unnecessaries of the compensation node at home, including those specialists who in their amplifiers use this node successfully. It is very regrettable that many teams-radio amateurs with distrust reacted reports to improving the quality of sound on the LF and MC with the inclusion of the compensator, which would have avoided this simple way to improve the operation of UMRs than the robbed themselves.

To document the truth, a small study was carried out. From the GZ-118 generator, a series of frequencies in the area of \u200b\u200bthe resonant frequency of the AU was filed on the UMP, the voltage was controlled by oscilloscope C1-117, and Kr on the AC terminals were measured by the INI C6-8, Fig.4. The R1 resistor is set to avoid filing to the compensator input while switching it between the control and shared wire. The experiment used common and public cables AC with a length of 3 m and a cross-section of 6 kV core. MM, as well as the GIGA FS IL speaker system with a frequency range of 25 -22.000 Hz, with a nominal resistance of 8 ohms and a rated power of 90 W firms of Acoustic Kingdom.

Unfortunately, the circuitry of the harmonic signal amplifiers from C6-8 provides for the use of high-capacity oxide capacitors in the circuits of the OOS. This leads to the effect of low-frequency noise of these capacitors to resolve the device on low frequencies, as a result, its permission on the NF is worse. When measuring the Kr signal with a frequency of 25 Hz from the GC-118, directly C6-8 the instrument readings dance around the value of 0.02%. Bypass this restriction with recorder filter The GZ-118 generator in the case of measuring the efficiency of the compensator is not possible, because A number of discrete settings of the 2T-filistic frequency settings are limited to LC values \u200b\u200b20.60, 120, 200 Hz and does not allow you to measure Kr on the frequencies you are interested in. Therefore, fastening the heart, the level of 0.02% was adopted as zero, reference.

At a frequency of 20 Hz at a voltage at the AC 3 terminals in the AMPL, which corresponds to the output power of 0.56 W on a load of 8 ohms, Kr was 0.02% with the compensator turned on and 0.06% after it is turned off. At a voltage of 10 V AMPL, which corresponds to the output power of 6.25 W, the value of Kr 0.02% and 0.08%, respectively, at a voltage of 20 V AMPL and power 25 W - 0.016% and 0.11%, and at voltage 30 In AMPL and power 56 W - 0.02% and 0.13%.

Knowing the facilitated relationship of imported equipment manufacturers to the values \u200b\u200bof the inscriptions relating to the capacity, as well as remembering the wonderful, after the adoption of Western standards, the transformation of the 35as-1 acoustic system with a low-frequency loudspeaker in S-90, the long-term power of more than 56 W on AC has not been applied.

At a frequency of 25 Hz, with a power of 25 watts, Kr was 0.02% and 0.12% with the / off compensation node, and with a capacity of 56 W - 0.02% and 0.15%.

At the same time, the need for the effectiveness of the exit vials of the total OOS was checked. At a frequency of 25 Hz with a power of 56 W and is connected in one of the AC cable wires of the output RL-RC FNH, similar to the required in the superlines, Kr with a discovered compensator reaches 0.18%. At a frequency of 30 Hz with a power of 56 W km 0.02% and 0.06% with the on / off compensation node. At the frequency of 35 Hz with a power of 56 W km 0.02% and 0.04% with the on / off compensation node. At frequencies 40 and 90 Hz with a capacity of 56 W km 0.02% and 0.04% with the on / off compensation node, and at a frequency of 60 Hz -0.02% and 0.06%.

Conclusions are obvious. There is a nonlinear signal distortion on the AC terminals. The degradation of the linearity of the signal at the AC terminals is clearly recorded with the inclusion of it through an uncompensated, not covered by the UNFC resistance containing 70 cm relatively thin wire. The dependence of the level of distortion from the power supply to the AC power suggests that it depends on the ratio of the signal power and the rated power of the NF loudspeakers of the AU. The distortions are most pronounced at frequencies near the resonant. The speakers generated in response to the impact of the sound signal of the anti-EDS is shunting the sum of the output resistance of the UMP and the resistance of the cable wires of the AC, so the level of distortion on the terminals AC directly depends on the resistance of these wires and the output resistance of the amplifier.

The diffuser of a poorly damping low-frequency loudspeaker itself radiates the pride, and, in addition, this loudspeaker generates a wide tail of products of nonlinear and intermodulation distortions that reproduces the mid-frequency loudspeaker. This explains the deterioration of the sound in medium frequencies.

Despite the instrument of the zero level of Kr 0.02% accepted due to the impermanence, the influence of the cable resistance compensator on the distortion of the cigal on the AC terminals is noted clearly and uniquely. You can install the full compliance of the conclusions made after listening to the compensation node on the music signal, and the results of the instrumental measurements.

The improvement that is clearly audible when the cable physicist is turned on can be explained by the fact that with the disappearance of distortions on the AC terminals, the mid-frequency loudspeaker stops playing all this dirt. Apparently, therefore, by reducing or eliminating distortion reproduction by the mid-frequency loudspeaker, a two-faced circuit of the inclusion of the AU, the so-called Bivearing, when the LF and Sch-RF links are connected by different cables, has an advantage in sound compared to a single-box diagram. However, since in a two-packed scheme, the distorted signal on the RVC terminals does not disappear anywhere, this scheme loses the option with a complex by the coefficient of dumping the free oscillations of the low-frequency loudspeaker diffuser.

Physics will not be cheating, and for decent sound, it is not enough to obtain brilliant indicators at the outlet of the amplifier at the active load, but it is also necessary to lose linearity after delivery of the signal to the AC terminals. As part of a good amplifier, a compensator is absolutely necessary for one or another scheme.

Integrator.

The effectiveness and ability to reduce the error of the integrator on DA3 was also checked. In the UMP BB with OU TL071, the output constant voltage is within 6 ... 9 mV and reduce this voltage by turning on the additional resistor to the non-converting input circuit failed.

The effect of low-frequency noise characteristic of the OU with PT-input due to the coverage of the deep EOS through the frequency-visible chain R16R13C5C6 is manifested in the form of an instability of the output voltage of a value of several milcanity, or -60 dB relative to the output voltage at a nominal output power, at frequencies below 1 Hz not reproduced by the AU.

On the Internet mentioned a low resistance of the protective diodes VD1 ... VD4, which allegedly makes an error in the work of the integrator due to the formation of the divider (R16 + R13) / R VD2 | VD4 . . The inverse resistance of protective diodes was collected scheme Fig. 6. Here, the DA1, included according to the inverting amplifier scheme, is covered by the OOS through R2, its output voltage is proportional to the current in the chain of the Vd2 diode and the protective resistor R2 with a coefficient of 1 mV / on, and the resistance of the R2VD2 circuit with the coefficient of 1 mV / 15 gom. To exclude the influence of additive errors of the displacement and input current errors to the measurement of the diode leakage current, it is necessary to calculate only the difference between the OU's own voltage, measured without a diode being checked, and the voltage at the OU output after its installation. Almost the difference in the output voltages of OU into several Milvololt gives the value of the reverse resistance of the diode of about ten - fifteen gigas with reverse voltage of 15 V. Obviously, the leakage current will not become more with a decrease in the voltage on the diode to the level of several malelvolt, which is characteristic of the difference voltage of the integrator and compensator .

But the photo effect, which is characteristic of diodes placed in a glass case, really leads to a significant change in the output voltage of UMP. With the illumination of their incandescent lamp in 60 W, from a distance of 20 cm, a constant voltage at the yazch outlet increased to 20 ... 3o MV. Although it is unlikely inside the amplifier housing, a similar light level may be observed, a drop of paint, applied to these diodes, eliminated the dependence of the MODE modes from illumination. According to the results of the simulation, the response response ACH is not observed even at a frequency of 1 million. But it should not decrease the constant time R16R13C5C6. The phases of voltage variable at the outputs of the integrator and the compensator are opposite, and with a decrease in the capacitance capacitance or resistance of the integrator resistors, an increase in its output voltage may worsen the compensation of the resistance of the AC cables.

Comparison of the sound of amplifiers. The sound of the assembled amplifier was compared with the sound of several foreign amplifiers of industrial production. The source was the CBD-player of the Cambridge Audio CD player, a pre-amplifier "Radio engineering UE-001" was used for the swing and adjustment of the sound level of the UP-001, "SUGDEN A21A" and NAD C352 were used by regular adjustment authorities.

The first was checked by the legendary, empty and damn road English Umzch "Sugden A21a", working in class A with a 25 W output. What is noteworthy, in the accompanying documentation on the British, it was considered for the benefit of the level of nonlinear distortions not to indicate. Say, not in distortion, but in spirituality. "Sugden A21A\u003e" lost to the UMR BB-2010 with comparable power both in terms of and for clarity, confidence, sound nobility at low frequencies. This is not surprising, given the features of its scheme engineering: just a two-chain quasisymmetric output repeater on the transistors of one structure, assembled according to the circuitry of the 70s of the last century with a relatively high output resistance and on the output even more increasing the total output resistance by electrolytic capacitor - this is the last The decision in itself worsens the sound of any amplifiers on low and medium frequencies. At medium and high frequencies, the BB showed higher detail, transparency and excellent scene elaboration, when singers, tools could be clearly localized by sound. By the way, to the word about the correlation of objective data of measurements and subjective impressions from the sound: in one of the journal articles of competitors Sugden-A its Kr was determined at a level of 0.03% at a frequency of 10 kHz.

The next was also an English amplifier NAD C352. The overall impression was the same: the vividly pronounced "ward" sound of the Englishman on the sheet did not leave him any chance, while the work of the UMRs of BB was recognized as impeccable. Unlike the NADA, the sound of which was associated with thick shrubs, wool, wool, the sound of BB 2010 on medium and high frequencies made it clearly distinguishing the voices of performers in the general choir and tools in the orchestra. In the work of NAD C352, the effect of the best audibility of a more volatile artist, a loudest tool was clearly expressed. As the owner of the amplifier was put on, in the sound of BB BB, the vocalists did not "shine-nodes" each other, and the violin did not fought in the power of sound with a guitar or a pipe, but all the tools peacefully and harmoniously "were friends" in the overall sound image of the melody. At the high frequencies of the UMP-2010, according to figuratively thinking audiophiles, it sounds like that, "as if draws the sound with a thin-thin tassel." These effects can be attributed to the difference in the intermodulation distortions of amplifiers.

The sound of the RB RB 981 was similar to the sound of NAD C352, except better work At low frequencies, still the urzch of BB-2010 in the definition of AC control at low frequencies, as well as transparency, the sensitivity of the sound on medium and high frequencies remained out of competition.

The most interesting in terms of understanding the image of thinking of audiophiles was the general opinion that, despite the superiority over these three Umpsch, they bring the "warmth" sound than they make it more pleasant, and the Umzch BB works smoothly, "the sound is neutral."

The Japanese Dual CV1460 lost in sound immediately after turning on the most obvious to all, and spending time on his detailed listening. It kr was within 0.04 ... 0.07% at low power.

The main impressions of comparing the amplifiers in the main features were completely identical: the UMP BB was ahead of them in sound unconditionally and definitely. Therefore, further tests were recognized as unnecessary. As a result, friendship was defeated, each got the desired: for warm, sincere sound - Sugden, Nad and Rotel, and to hear the directed director - the UMR Vzch-2010.

Personally, I like high faithfulness to me like a light, clean, impeccable, noble sound, he played reproduce passengers of any complexity. As my friend, an audioophile with a lot of experience, the sounds of impact settings at low frequencies it works without options, as a press, on the middle it sounds as if it is not, and on high it seems to paint the sound with a thin tassel. For me, the unloading sound of the BB is associated with the ease of work of the cascades.

Literature

1. Sukhov I. Umzch high loyalty. Radio, 1989, No. 6, pp. 55-57; №7, p. 57-61.

2. Ridico L. Umzch BB on a modern element database with a microcontroller control system. "Radioofobby", 2001, №5, p. 52-57; №6, p. 50-54; 2002, №2, p. 53-56.

3. Ageev S. Super-linear umzch with deep OOS Radio, 1999, Nos. 10 ... 12; Radio, 2000, Nos. 1; 2; 4 ... 6; 9 ... 11.

4. Zuev. L. Umzch with parallel OOS. Radio, 2005, №2, p. 14.

5. Zhukovsky V. Why are the speed of UMP (or "UMPC-2008"). "Radioofobby", 2008, №1, p. 55-59; №2, p. 49-55.

UML BB-2010 is a new development from the widely known line of AMPs of the BB (high fidelity). A number of technical solutions were influenced by the work of Ageev.

Specifications:

Coefficient Harmonic at a frequency of 20000 Hz: 0.001% (150 W / 8 Ohm)

Small signal frequency band -3 dB: 0 - 800000 Hz

Output voltage growth rate: 100 V / μs

Signal / Noise and Signal / Background: 120 dB

Electrical Scheme for Air Force 2010

At the inlet of the amplifier is provided with R1C1 with a cutoff frequency of 1.6 Hz, Fig. 1. But the efficiency of the modes stabilization device allows the amplifier to work with an input signal containing up to 400 mw of the constant component. Therefore, C1 is excluded that it realizes the eternal audio dream of a path without capacitors and significantly improves the sound of the amplifier.

Operational amplifiers of preliminary amplifiers, the monthly OU is forced to develop several volts of the output voltage. Since the gain coefficient is small and ranges from 500 to 2000 times by 20 kHz, this indicates their operation with a relatively large voltage of the difference signal - from several hundred microwaves on the LF to several millivolts by 20 kHz and the high probability of entering the input cascade of the OU intermodulation distortion. The output voltage of these OU is equal to the output voltage of the last cascade of the gain of the voltage, which is usually made according to the scheme with OE. The output voltage in several volts indicates the operation of this cascade with rather large input and output voltages, and as a result - making it distortion into the enhanced signal. The OU is loaded on the resistance of the circuit parallel to the included circuits of the OOS and the load, which is sometimes somewhat kiloma, which requires from the output repeater of the output current amplifier to several milliamperes. Therefore, changes in the current of the output repeater IC, the output cascades of which consume no more than 2 mA currents are quite significant, which also indicates that they make distortions into the increased signal. We see that the input cascade, the stress enhancement cascade and the OU output cascade can cause distortion.

It is known that the level of distortion products coming to this frequency is reduced in proportion to the depth of the negative feedback for this frequency. The idling coefficient, to the coverage of the OOS amplifier, is impossible to measure at low frequencies due to the smallness of the input signal. According to calculations developed before coverage, the strengthening of idling allows to achieve the depth of the EOS 104 dB at frequencies of up to 500 Hz. Measurements for frequencies, starting with 10 kHz, show that the depth of the EOS at a frequency of 10 kHz reaches 80 dB, at a frequency of 20 kHz - 72 dB, at a frequency of 50 kHz - 62 dB and 40 dB - at a frequency of 200 kHz. Figure 2 shows the amplitude-frequency characteristics of the UMPC 2010 and, for comparison, similar in complexity.

The use of a linearizing resistor R17 resistance to 1 kΩ in the differential cascade VT1, VT2 on the transistors of different structures with serial power increases the linearity of conversion of the OU DA1 output voltage in the VT2 collector current by creating a local OOS with a depth of 40 dB. This can be seen from the comparison of the amount of emitters of VT1, VT2 emitters - about 5 ohms - with the resistance R17, or the sum of thermal stresses VT1, VT2 is about 50 mV - with a drop of voltage at the resistance R17, which makes 5.2 - 5.6 V .

Three-kalid output repeater is assembled on bipolar transistors and special comments does not require. Do not try to fight entropy, saving on a rest of the weekend transistors. It should not be less than 250 mA; In the author - 320 mA.

The current protection node prevents damage to the output transistors with short circuits in the load. The current sensor serve resistors R53 - R56 and R57 - R60, which is quite enough. The flow of the amplifier's output currents through these resistors creates a voltage drop, which is applied to the R41R42 divider. The voltage with the value of the threshold opens the VT10 transistor, and its collector current opens the VT8 VT8VT9 trigger cell. This cell passes into a stable state with open transistors and shunt the HL1VD8 chain, reducing the current through the stabilion to zero and locking the VT3. The C21 discharge of the VT3 base current can take several milliseconds. After the trigger cell is triggered, the voltage on the bottom of the C23, charged with the voltage on the HL1 LED to 1.6 V, rises from the level -7.2 in the positive power supply of UN to level -1.2 B1 voltage on the top of this capacitor also rises 5 V. C21 quickly discharged through the R30 resistor on C23, the VT3 transistor is locked. Meanwhile, VT6 opens and through R33, R36 opens VT7. VT7 shunt stabilodron VD9, discharges through R31 C22 capacitor and locks the VT5 transistor. Without receiving offset voltages, the output cascade transistors are also locked.

Restoring the original status of the trigger and the activation of the UMR is performed by pressing the SA1 button "Reset protection". C27 is charged with a current collector VT9 and shunt the VT8 base chain by locking the trigger cell. If by this moment the emergency situation is eliminated and the VT10 locked, the cell goes into a state with steadily closed transistors. VT6, VT7 are closed, on the VT3, VT5 database, the reference voltage and the amplifier enters the operating mode. If the short circuit in the load of the UMR continues, the protection is triggered again, even if the C27 capacitor is connected to SA1. Protection works so effectively that during work on configuring the correction, the amplifier was de-energged several times for small repairs, touching the unconvertising input. The resulting self-excitation led to an increase in the current of the output transistors, and the protection turned off the amplifier. Although it is impossible to offer this coherent method as a rule, but thanks to current protection, it did not harm the output transistors.

Work compensator for resistance cables

To document the truth, a small study was carried out. From the GZ-118 generator, a series of frequencies in the area of \u200b\u200bthe resonant frequency of the AU was filed on the UMP, the voltage was controlled by oscilloscope C1-117, and Kr on the AC terminals were measured by the INI C6-8, Fig.4. Checking the resistance efficiency The R1 wiring system is set to avoid tipping on the compensator input while switching it between the control and shared wire. The experiment used common and public cables AC with a length of 3 m and a cross-section of 6 kV core. MM, as well as the GIGA FS IL speaker system with a frequency range of 25-22000 Hz, with a nominal resistance of 8 ohms and a nominal capacity of 90 W of the company ACOstic Kingdom.

Unfortunately, the circuitry of the harmonic signal amplifiers from C6-8 provides for the use of high-capacity oxide capacitors in the circuits of the OOS. This leads to the influence of low-frequency noise of these capacitors to resolve the device at low frequencies, as a result of which its permission on the NF is worse. When measuring the Kr signal with a frequency of 25 Hz from the GC-118, directly C6-8 the instrument readings dance around the value of 0.02%. Bypassing this restriction with the help filter of the GZ-118 generator in the case of measuring the efficiency of the compensator, it is not possible, because A number of discrete setting frequencies 2T-fil-TRTs are limited to LF values \u200b\u200b20, 60, 120, 200 Hz and does not allow you to measure Kr on frequency you are interested in. Therefore, fastening the heart, the level of 0.02% was adopted as zero, reference.

Knowing the facilitated relationship of imported equipment manufacturers to the values \u200b\u200bof the inscriptions relating to the power, as well as remembering the wonderful, after the adoption of Western standards, the transformation of the acoustic system with a low-frequency loudspeaker capacity of 30 W B, the long-term power of more than 56 W on AC has not been applied.

At a frequency of 25 Hz, with a power of 25 watts, Kr was 0.02% and 0.12% with the / off compensation node, and with a capacity of 56 W - 0.02% and 0.15%.

Despite the assumption of the zero level of Kr in 0.02% accepted due to the non-idealness, the influence of the cable resistance compensator on the distortion of the cigal on AC is observed and definitely noted. You can install the full compliance of the conclusions made after listening to the compensation node on the music signal, and the results of the instrumental measurements.

Integrator

The Internet mentioned the low resistance of the VD1 ... VD4 protective diodes, which allegedly makes an error in the operation of the integrator due to the formation of a divider (R16 + R13) / R VD2 | VD4 .. The diagram of the reverse resistance of the protective diodes was collected. 6. Here, the DA1, included according to the inverting amplifier scheme, is covered by an OOS through R2, its output voltage is proportional to the current in the circuit of the VD2 diode and the protective resistor R2 with a coefficient of 1 mV / on, and the R2VD2 chain resistance is 1 mV / 15 gom . To exclude the influence of additive errors of the displacement and input current errors to the measurement of the diode leakage current, it is necessary to calculate only the difference between the OU's own voltage, measured without a diode being checked, and the voltage at the OU output after its installation. Almost the difference in the output voltages of OU into several Milvololt gives the value of the reverse resistance of the diode of about ten - fifteen gigas with reverse voltage of 15 V. Obviously, the leakage current will not become more with a decrease in the voltage on the diode to the level of several malelvolt, which is characteristic of the difference voltage of the integrator and compensator .

Comparison of the sound of amplifiers. The sound of the assembled amplifier was compared with the sound of several foreign amplifiers of industrial production. The source was the Cambridge Audio CD player, a pre-amplifier "", "SUGDEN A21A" and NAD C352 was used to ripping and adjusting the sound level of the "SUGDEN A21A" and NAD C352.

The sound of the Rotel RB 981 was similar to the sound of NAD C352, with the exception of better operation at low frequencies, still the UMPs of BB-2010 in the definition of AC control at low frequencies, as well as transparency, the sensitivity of the sound on medium and high frequencies remained out of competition.

The Japanese Dual CV1460 lost in sound immediately after turning on the most obvious to all, and spending time on his detailed listening. It kr was within 0.04 ... 0.07% at low power.

UMSHC-2011 ultimate version

UMPs Air Force-2011 version Ultimate Scheme author Viktor Zhukovsky G. Krasnoarmeysk

Technical characteristics of the amplifier:
1. High power: 150 W / 8th Ohm,
2. High linearity - 0.000.2 ... 0.000.3% at 20 kHz 100 W / 4 Ohm,
Full set of service units:
1. Maintain zero constant voltage,
2. Compensator of the resistance of wire wires,
3. Clean protection,
4. Protection against constant output voltage,
5. Smooth start.

UMBC of the Air Force 2011 scheme

The publisher of printed circuit boards was engaged in the participant of many popular projects LEPEKHINV (Vladimir Lepjin). It turned out very well).

Umzch-Air Force2011 fee

Pay amplifier UCH Air Force-2011. It was designed for a tonne blowing (parallel to the radiator). Installation of transistors Un (voltage amplifier) \u200b\u200band VC (output cascade) is somewhat difficult, because Installation / disassembly has to be screwed across the holes in the PP with a diameter of about 6 mm. When access is open, the projection of transistors does not fall under PP, much more convenient. I had to make a fee a little.

In the new PP, did not take one point - This is the convenience of setting up protection on the amplifier board:

C25 0.1N, R42 * 820 Ohm and R41 1K All elements of the SMD and are from the soldering side, which is not very convenient when setting up, because It will be necessary to unscrew several times and screw the fastening bolts of PP on racks and transistors to radiators. Sentence: R42 * 820 consists of two resistors of the SMD located in parallel, from here. Offer: one resistor RMD is searched immediately, another output resistor can be soldered to VT10 one output to the database, the other to the issuer, we select to the appropriate. Posiced, change withdrawal on the SMD, for clarity:

The sound frequency amplifier (UMP) of high loyalty (BB), developed in 1989 by Nikolai Sukhov, can already be called legendary with full right. With its development, a professional approach based on knowledge and experience in the field of analog scheme engineering was applied. As a result, the parameters of this amplifier were so high as today, this design did not lose relevance. This article describes a somewhat enhanced version of the amplifier. Improvements are reduced to the use of a new element base and the use of a microcontroller control system.

Power amplifier (mind) is an integral part of any audio reproducing complex. Available a lot of descriptions of the design of such amplifiers. But in the overwhelming majority of cases, even with very good characteristics, there is a complete lack of service amenities. But at present, when microcontrollers were widely distributed, it is not difficult to create a fairly perfect management system. At the same time, the homemade apparatus for functional saturation may not yield to the best proprietary samples. The variant of the UMP with the microcontroller control system is shown in Fig. one:

Fig. 1. Appearance of the amplifier.

The source diagram of UMPs has sufficient parameters so that the amplifier is not the dominant source of the nonlinearity of the sound producing path in the entire range of output power. Therefore, further improvement of the characteristics of noticeable advantages does not give.

At the very least, the sound quality of different phonograms is much more different than the sound quality of amplifiers. On this topic, you can bring a quote from the "Audio" magazine: " There are obvious differences in such categories as speakers, microphones, LP pickups, listening rooms, studio rooms, concert halls and, especially, configurations of studios and recording equipment used by various recording companies. If you want to hear thin differences in the sound scene, compare John Eargle entries to Delos with Jack Renner entries on Telarc, and not pre-amplifiers. Or if you want to hear subtle differences in transitions, compare DMP studio jazz records with Jazz records Cheshky Studio, and not two inter-block cables.»

Despite this fact, Hi-End lovers do not stop the search for the "right" sound, which affect, including the mind. In fact, the mind is an example of a very simple linear path. The current level of development of circuit equipment allows us to provide enough high parameters for such a device so that the accuracy of the distortion become invisible. Therefore, in practice, two any modern, non -excentricly designed mind sound the same. On the contrary, if the mind has some special, specific sound, it speaks only one thing: the distortion of the distortion is great and well visible on the ear.

This does not mean that it is very simple to design a high-quality mind. There are many subtleties as a circuitry and constructive plan. But all these subtleties have long been known to serious manufacturers of the mind, and gross mistakes in the designs of modern mind is usually not found. Exception is expensive Hi-End class amplifiers, which are often designed very illiterately. Even if the misfortune misses are enjoyable on a rumor (which they say lovers of lamp amplifiers), it has nothing to do with high loyalty.

The high-quality mind, except for the traditional requirements of broadband and good linearity, is made another number of additional requirements. Sometimes you can hear that for home use The power of the amplifier 20-35 W is sufficient. If we are talking about medium power, then such an assertion is true. But the real music signal may have a peak power level greater than the average level of 10-20 times. Therefore, so that with an average power of 20 W, it is necessary to have a power of about 200 W. Here, for example, the output of the expert assessment for the amplifier described in: " The only comment was the lack of volume of the sound of large shock tools, which is explained by the insufficient output power of the amplifier (120 W in the peak at the load 4 Ohm).»

Acoustic systems (AC) are a complex load and have a very complex nature of the dependence of the total resistance from the frequency. At some frequencies, it may be less than the nominal value of 3-4 times. The mind should be able to work without distortion on such a low-voltage load. For example, if the nominal resistance of the acoustic system is 4 Ohm, the mind must normally work on the load with resistance of 1 Ohm. This requires very large output currents, which should be taken into account when designing the mind. The described amplifier satisfies these requirements.

Recently, the theme of the optimal output resistance of the amplifier in terms of minimizing AU distortions is quite often discussed. However, this topic is relevant only when designing active speakers. Separation filters of passive speakers are developed based on the fact that the signal source will have a negligible low output resistance. If the mind will have a high output resistance, then the frequency response will be strongly distorted. Therefore, nothing else remains how to ensure a small output resistance for the mind.

It can be noted that the new developments of the mind go mainly along the path of reduction, improving the process of construction, an increase in output power, an increase in efficiency, improve consumer qualities. This article focuses on service functions that are implemented due to the microcontroller control system.

The amplifier is made in the MIDI format housing, its overall dimensions 348x180x270 mm, weight is about 20 kg. The built-in microcontroller allows you to control the amplifier using the IR remote control (common with pre-amplifier). In addition, the microcontroller is measured and indicating the average and quasipic output power, the temperature of the radiators, implements the timer shutdown and processes emergency situations. The amplifier protection system, as well as the control of the power on and off, is implemented with the participation of the microcontroller. The amplifier has a separate duty power supply, which allows it to be in the "Standby" mode, when the main power sources are turned off.

The described amplifier is called NSM (National Sound Machines), model PA-9000, since the name of the device is part of its design and must be present. The realized set of service functions in some cases may be redundant, for such situations, a "minimalist" version of the amplifier (model PA-2020) has been developed, which has only a power switch and two-color LED on the front panel, and the built-in microcontroller only controls the power on and off process, Completes the protection system and provides remote control of the "Standby" mode.

All controls and indications of the amplifier are located on the front panel. Its appearance and appointment of controls are shown in Fig. 2:

Fig. 2. Front amplifier panel.

1 - LED Enable External Consumers EXT	9 - Minus button
2 - DUTY duty duty	10 - PEAK Pic Power Indication Button
3 - Transition button in standby standby mode	11 - Timer Timer Indication Button
4 - Full power off button Power	12 - Temperature Indication Button° C.
5 - LED Main Power LED	13 - Button Plus
6 - Operate Normal LED LED	14 - LED crash left channel Fail L
7 - Load LED Load	15 - LED Right-Channel LED Fail R
8 - Display

Power button Provides full shutdown of the amplifier from the network. Physically, this button disconnects only the duty power source from the network, respectively, it can be calculated on a small current. The main power sources are included using the relay, the windings of which are powered by the duty source. Therefore, when the "POWER" button is turned off, all the amplifier circuits are guaranteed.

When you turn on the POWER button, the amplifier is fully turned on. The inclusion process occurs as follows: the duty source immediately turns on, as evidenced by the LED on the on-duty power supply "DUTY". After some time necessary to reset the microcontroller, the power on exterior sockets And the "EXT" LED is lit. Then the "Main" LED is lit, and the first stage of incorporating the main sources occurs. Initially, the main transformers are included through restrictive resistors that prevent initial current throw due to discharged filter capacitors. Capacitors are gradually charged, and when the measured supply voltage reaches the installed threshold, the restrictive resistors are excluded from the chain. This ignites the Operate LED. If for the allotted time, the supply voltage has not reached the installed threshold, the process of turning on the amplifier is interrupted and the accident indication turns on. If the inclusion of the main sources has passed successfully, the microcontroller checks the status of the protection system. In the absence of emergency situations, the microcontroller allows the switching on the load relay and the Load LED is lit.

STANDBY button Managing the standby mode. A short press of the button put the amplifier into the standby mode or, on the contrary, turns on the amplifier. In practice, you may need to enable external sockets, leaving the mind in standby mode. This is required, for example, when listening to phonograms for stereo telephones or when overwriting without sound control. External sockets can be independently turned on-off long (to sound signal) by pressing the "Standby" button. An option when the mind is turned on, and the sockets are turned off, it does not make sense, therefore it is not implemented.

On the front panel there are 4-bit digital display and 5 display control buttons. The display can operate in the following modes (Fig. 3a):

disabled
indication of the middle output power [w]
indication of quasipic output power
timer status indication [M]
indication of radiators temperature [° C]

Immediately after enabled, the display is disabled, since in most cases when operating the mind it is not needed. You can turn on the display by pressing one of the "PEAK", "Timer" or "° C" buttons.

Fig. 3. Display display options.

PEAK button Includes displaying output power and switches medium / quasipic power modes. In the output power indication mode, "W" is ignited on the display, and for quasipic power - also "PEAK". The output power is indicated in watts with a discreteness of 0.1 watt. Measurement is performed by multiplying current and voltage on the load, so the readings are valid for any permissible load resistance value. Hold the "PEAK" button to the audio signal turns off the display. Turning off the display, as well as its switching between different indication modes occurs smoothly (one image "flies" to another). This effect is implemented programmatically.

Button "Timer" Displays the current state of the timer on the display, while the letter "M" is ignited. The timer allows you to set the time interval by the expiration of which the amplifier goes into the standby mode and the external sockets are disconnected. It should be noted that when using this feature, other components of the complex must allow power off "on the go". For a tuner and a CD player, this is usually permissible, but in some cassette dections, when the power is turned off, the LPM may not move to the "stop" mode. For such Dec, turning off the power during playback or record is unacceptable. However, among the corporate devices, such decks are extremely rare. On the contrary, most Dec has a "Timer" switch, which has 3 positions: "OFF", "Record" and "Play", which allows a simple power supply to immediately turn on playback or recording mode. Turn off these modes can also be placed easy to remove the power. The amplifier timer can be programmed to the following intervals (Fig. 3b): 5, 15, 30, 45, 60, 90 and 120 minutes. If the timer is not used, it must be translated into the "OFF" state. In this state it is immediately after the power is turned on.

Timer interval task is carried out buttons "+" and "-" In the timer indication mode. If the timer is on, the "Timer" LED is always on the display, and the timer indication turns on the actual current state, i.e. How many minutes left before shutdown. In such a situation, the interval can be extended by pressing the "+" button.

"° C" button Includes the display of radiators temperature, while the symbol "° C" is ignited. A separate thermometer is installed on each radiator, but the maximum temperature value is displayed. These same thermometers are used to control the fan and for the temperature protection of the output transistors of the amplifier.

For display indications Two LEDs are located on the front panel: "Fail Left" and "Fail Right". When the protection is triggered in one of the channels, the corresponding LED is ignited, and the display of the cause of the accident is indicated (Fig. 3c). In this case, the amplifier goes into the standby mode. The following types of protection are implemented in the amplifier:

overload protection for output cascade
protection against the permanent component at the output
protection from the power source
protection against the disappearance of network voltage
protection against overheating output transistors

Current overload protection Reacts to the excess of the specified threshold of the output cascade. It saves not only the speakers, but also output transistors, for example, with a short closure at the outlet of the amplifier. This is the protection of a trigger type, after it is triggered, the mind is restored only after it is re-enabled. Since this protection requires high speed, it is implemented hardware. The display is indicated as "if".

Reacts to the constant component of the output voltage of the mind, greater than 2 V. It protects the speakers, is also implemented hardware. The display is indicated as "DCF".

Reacts to the drop in the supply voltage of any shoulder below the specified level. A significant disruption of the symmetry of the supply voltage can cause the permanent component at the output, which is dangerous to the AU. The display is indicated as "UF".

Reacts to the loss of several periods of network voltage in a row. The purpose of this protection is to turn off the load before the supply voltage falls and the transition will begin. It is implemented hardware, the microcontroller only reads its condition. The display is indicated as "PrF".

overheat protection Output transistors are implemented programmatically, it uses information with thermometers that are installed on radiators. The display is indicated as "TF".

The mind has the ability remote control . Since it does not require a large number of control buttons, the same remote control is used as to control the pre-amplifier. This remote control works in the RC-5 standard and has three buttons specifically designed to manage the mind. The "Standby" button completely duplicates the same button on the front panel. The "display" button allows you to switch the display mode over the ring (Fig. 3a). Hold the "Display" button to the audio signal turns off the display. The "MODE" button allows you to change the timer time interval (Fig. 3b), i.e. It replaces the "+" and "-" buttons.

On the rear panel Amplifier (Fig. 4) Set sockets intended for powering other components of the complex. These sockets have an independent shutdown, which allows the entire complex from the remote control.

Fig. 4. Rear Amplifier panel.

As noted earlier, as the basis of the Amplifier described, the UMPC scheme of Nikolai Sukhova was taken, which is described in. The basic principles of constructing the mind of high loyalty are set forth in. Schematic scheme the main boost of the amplifier shown in Fig. five.

width \u003d 710\u003e

Fig. 5. Schematic diagram of the main amplifier board.

Compared to the original design, small changes were made to the amplifier. These changes are not fundamental and are mainly a transition to a newer element base.

Changed temperature stabilization circuit. In the original design, together with the output transistors on the radiators, the transistor was installed - the temperature sensor that set the output cascade displacement voltage. At the same time, the temperature of only output transistors was taken into account. But the temperature of the forerunner transistors due to the rather large power dissipation on them also increased significantly during operation. Due to the fact that these transistors were installed on small separate radiators, their temperature could rather fluctuately fluctuate, for example, as a result of changing the power dissipated or even due to external air flows. This led to the same sharp fluctuations in rest current. Yes, and any other element of the mind can be very hot during operation, since in one case there are heat sources (radiators of output transistors, transformers, etc.). This also applies to the very first transistors of the composite emitter repeater, which did not have radiators at all. As a result, the rest current could increase several times when the mind is heated. The solution to this problem was proposed by Alexei Belov.

Usually, for the temperature stabilization of the current of the output cascade, the mind is used next scheme (Fig. 6a):

Fig. 6. Temperature stabilization scheme of rest current.

The offset voltage is applied to the points A and B. It is highlighted on a two-pole, which consists of the VT1 transistor and resistors R1, R2. The initial offset voltage is set by the R2 resistor. The VT1 transistor is usually fixed with the VT6, VT7 radiator. Stabilization is as follows: When the transistors of VT6, VT7 is heated, the fall of the base-emitter decreases, which, with a fixed bias voltage, leads to an increase in rest current. But with these transistors, VT1 is heated, which causes a decrease in the voltage drop on a two-pole, i.e. Reducing the reservoir. The disadvantage of such a scheme is that the temperature of transitions of other transistors included in the composite emitter repeater is not taken into account. To consider it, the temperature of the transitions of all transistors should be known. The easiest way to make it the same. For this, all transistors included in the composite emitter repeater are sufficiently installed on a common radiator. At the same time, to obtain a current of rest dependent on temperature, the displacement voltage of the composite emitter repeater must have the temperature coefficient of the same as the six transitions enabled. Approximately we can assume that the direct drop voltage on the P-N transition linearly decreases with a coefficient k, approximately 2.3 mV / ° C. At the composite emitter repeater, this coefficient is 6 * to. Provide this temperature coefficient of offset voltage - the task of a two-pole, which turns on between points A and B. Two-pole, shown in Fig. 6A, has a temperature coefficient equal to (1 + R2 / R1) * k. When adjusting the R2 resistor, the reservoir current changes the temperature coefficient, which is not entirely correct. The simplest practical solution can be the scheme shown in Fig. 6b. In this scheme, the temperature coefficient is (1 + R3 / R1) * k, and the starting current of the rest is set by the position of the R2 resistor. The voltage drop on the R2 resistor, which is hosted by a diode, can be considered almost constant. Therefore, the adjustment of the initial and rest current does not affect the temperature coefficient. With such a scheme, when heated, the mind of the rest current changes no more than 10-20%. In order for all transistors of the composite emitter repeater to be placed on a general radiator, they must have housings suitable for attachment on the radiator (transistors in the TO-92 enclosures are not suitable). Therefore, other types of transistors are applied to the mind, at the same time more modern.

In the amplifier diagram (Fig. 5), the two-hectare of temperature stabilization of the rest current is hosted by a C12 capacitor. This capacitor is not mandatory, although it also does not bring any harm. The fact is that between the databases of the composite emitter repeater, it is necessary to provide a displacement voltage, which must be permanent for the selected quiet current and do not depend on the enhanced signal. In short, the variable component of the voltage on the two-pole, as well as on the resistors R26 and R29 (Fig. 5) should be zero. Therefore, all these elements can be covered with condensers. But due to the low dynamic resistance of the two-pole, as well as low values \u200b\u200bof the resistance of these resistors, the presence of shunting containers affects very weakly. Therefore, these containers are not required, especially since their rates should be rather large (about 1 μF and 10 μF, respectively) for shunting R26 and R29).

Output transistors The mind is replaced by CT8101A transistors, CT8102A, which have a higher boundary frequency Current transmission coefficient. W. powerful transistors The effect of the current transmission coefficient is rather pronounced by increasing the collector current. This effect is extremely undesirable for the mind, since here transistors have to work at large output. Modulation of current transmission coefficient leads to a significant deterioration in the linearity of the output cascade of the amplifier. To reduce the effect of this effect, a parallel inclusion of two transistors was applied in the output cascade (and this is the minimum that you can afford).

For parallel inclusion Transistors To reduce the effect of scattering their parameters and aligning working currents, separate emitter resistors are applied. For normal operation of the current overload protection system, the maximum voltage value on VD9 diodes is added to VD9 - VD12 (Fig. 5), as it is necessary to remove the fall from two, but from four emitter resistors.

Other transistors The composite emitter repeater is CT850A, KT851A (TOO-220 case) and KT940A, KT9115A (T-126 housing). In the area stabilization scheme, the composite transistor Kt973a is applied (T-126 housing).

Produced and replacement OU on more modern. The main UU U1 is replaced by AD744, which has increased speed and good linearity. OU U2, which operates in the scheme of maintaining the zero potential at the OMPC output, is replaced by OP177, which has a low zero offset (no more than 15 μV). This made it possible to abandon the trimming resistor of the displacement adjustment. It should be noted that due to the features of the AD744 circuitry, the U2, the U2 should provide an output voltage close to the power voltage (output 8 AU AD744 by constant voltage is the output of 4 only two P-n transitions). Therefore, not all types of precision OU are suitable. In extreme cases, you can apply a "pull-up" resistor from the OU to -15 V. OU U3, which operates in the impedance scheme of the AC connecting wires, is replaced by the AD711. The parameters of this OMA are not so critical, so a cheap OU has been chosen with sufficient speed and a rather low zero offset.

The resistor divisors R49 - R51, R52 - R54 and R47, R48 are added to the circuit, which serve to remove current and voltage signals for power measurement circuit.

Modified implementation earth chains. Since now every amplifier channel is fully assembled on the same board, the need for multiple earthwoods, which must be connected at one point on the chassis. Special topology pCB Provides star-shaped excavation of earth chains. The star of the Earth is connected by one conductor with a common output of the power supply. It should be noted that such a topology is suitable only with fully separated sources of left and right channels.

In the original wavelength amplifier scheme for variable current covers I. relay Contactsthat connect the load. This measure is adopted to reduce the influence of nonlinearity of contacts. However, there are problems with the work of protection on the constant component. The fact is that when the amplifier is turned on, the power is supplied earlier than the load relay turns on. At this time, a signal may be present at the input, and the amplifier transmission coefficient due to the broken feedback loop is very large. In this mode, the mind limits the signal, and the offset voltage compensation scheme is generally unable to maintain the mind value of the constant component at the output. Therefore, even before connecting the load, it may be found that a constant component is present at the output, and then the protection system will work. Eliminate this effect is very easy if you use relays with switchable contacts.

Normally-closed contacts must close the OEO loop in the same way as well-open. At the same time, when the relay is trigged, the feedback turns out to be broken only for a very short time, during which all the contacts are open with the relay. During this time, relatively inertial protection on the constant component does not have time to work. In fig. 7 shows the process of switching a relay shot by a digital oscilloscope. As can be seen, after 4 ms after supplying the voltage to the relay winding, normal-closed contacts are blocked. Approximately after another 3 ms, normally open contacts are closed (with a noticeable bounce, which lasts about 0.7 ms). Thus, in the flight "contacts are about 3 ms, it is at that time feedback will be broken.

Fig. 7. The switching process of the relay AJS13113.

Protection scheme Fully recycled (Fig. 8). Now it is placed on the main board. Thus, each channel has its own independent scheme. It is somewhat redundant, but each basic board is completely autonomous and is a complete monophonic amplifier. Part of the protective functions carries a microcontroller, but to increase the reliability, the sufficient set is implemented by hardware. In principle, the amplifier board can work at all without a microcontroller. Since the mind has a separate duty power source, protection scheme is powered by it (level + 12V). This makes the behavior of the protection scheme more predictable at an accident of one of the main power sources.

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Fig. 8. Amplifier protection scheme.

Current overload protection Includes trigger collected on transistors VT3, VT4 (Fig. 5), which is included when opening the VT13 transistor. VT13 receives a signal from the current sensor and opens when the value of the R30 set is set by the value of the R30 set by the current resistor. Trigger turns off the current generators VT5, VT6, which leads to locking all transistors of the composite emitter repeater. The zero voltage at the output is maintained in this mode using the R27 resistor (Fig. 5). In addition, the condition of the trigger is read through the chain VD13, R63 (Fig. 8), and when it turns on, a low logical level is installed on the inputs of the logical element U4D. The VT24 transistor provides an open collector output for an IOF signal (I Out Fail), which is interviewed by a microcontroller.

Protection against the constant component Implemented on transistors VT19 - VT22 and logical elements U4B, U4A. The signal from the output of the amplifier through the R57 divider, R59 enters the R58C23 vdnch with a slice frequency of about 0.1 Hz, which highlights the constant component of the signal. If a constant component of positive polarity appears, the transistor VT19 is opened, included according to the OE scheme. In turn, opens the VT22 transistor, and a high logical level appears on the inputs of the U4B logical element. If a constant component of the negative polarity appears, the VT21 transistor is opened included with OB. Such asymmetry is a forced measure associated with unipolar nutrition Protection schemes. In order to increase the current transmission coefficient, the VT21, VT20 transistors (OK) transistors are applied. Further, as in the first case, the transistor VT22 opens, etc. A VT23 transistor is connected to the U4A logical element output, which provides an open collector output for DCF (DC FAIL).

Protection against the disappearance of network voltage Contains auxiliary rectifier (Fig. 13) VD1, VD2 (VD3, VD4), which has a smoothing filter with a very small time constant. If several periods of network voltage drop out of a row, the output voltage of the rectifier drops, and a low logical level is set at the inputs of the logical element U4C (Fig. 8).

Logical signals from the three defense schemes described above are entering the element "or" U5C, at the output of which a low logical level is formed in case of triggering any of the schemes. At the same time, the C24 condenser is discharged through the VD17 diode, and a low logical level appears on the inputs of the U5B logical element (also at the U5A output). This leads to the closure of the VT27 transistor and disconnect the relay K1. The R69C24 chain provides some minimal delay when power is turned on in case the microcontroller for some reason does not form an initial delay. The VT25 transistor provides an open collector output for OKL (OK LEFT) or OKR (OK Right). The microcontroller may prohibit the switching on the relay. To do this, the VT26 transistor is installed. This feature is necessary to implement the program protection against overheating, software delay on the relay and to synchronize the operation of the protection systems of the left and right channels.

Microcontroller interaction with hardware protection scheme Next: When the amplifier is turned on, after the supply voltage has reached the nominal value, the microcontroller polls the OKL and OKR hardware protection signals. All this time, the switching on the relay is prohibited by a microcontroller by maintaining the ENB (Enable) signal in a high logic state. As soon as the microcontroller receives readiness signals, it generates a temporary delay and allows the switching on the relay. During the operation of the amplifier, the microcontroller monitors the readiness signal all the time. In case of disappearance of such a signal for one of the channels, the microcontroller removes the ENB signal, turning off the relay in both channels. It then polls the status of protection status to identify the channel and the type of protection.

overheat protection Implemented fully programmatically. In the case of overheating of radiators, the microcontroller removes the ENB signal, which causes a shutdown of the load relay. Dallas DS1820 thermometer is enshrined to measure the temperature on each of the radiators. The protection is triggered when the temperature radiators reach 59.8 ° C. Somewhat earlier, at a temperature of 55.0 ° C, the display appears preliminary message Overheating - the temperature of the radiators is automatically output. The re-activation of the amplifier occurs automatically when the radiators is cooled to 35.0 ° C. The inclusion at a higher temperature of the radiators is possible only manually.

To improve the cooling conditions of elements inside the amplifier housing, a small-sized fanwhich is located on the rear panel. A fan with an inscoleton engine is applied direct current With a nominal supply voltage of 12 V, designed to cool the computer processor. Since there is some noise when the fan is working, which can be noticeable in pauses, a rather complex control algorithm is used. At a temperature of radiators 45.0 ° C, the fan begins to work, and when the radiators is cooled to 35.0 ° C, the fan is turned off. At the output power of less than 2 W, the fan operation is prohibited so that its noise is noticeable. To prevent periodic inclusions and turn off the fan when the output power fluctuates near the threshold value, the minimum fan turning time is limited to the 10 seconds. At a temperature of radiators 55.0 ° C and above, the fan runs without shutdowns, since this temperature is close to an emergency. If the fan turned on when the amplifier is running, then when the "Standby" mode is input, if the temperature of the radiators is above 35.0 ° C, the fan continues to work even at zero output power. This allows you to quickly cool the amplifier.

Protection from the power source Also implemented fully programmatically. The microcontroller using the ADC monitors the power supply voltages of both channels of the amplifier. This voltage enters the processor from the main boards through resistors R55, R56 (Fig. 8).

The inclusion of the main power sources is steady. This is necessary for the reason that the load of rectifiers are fully discharged filter capacitors, and a strong current throw will occur with a sharp turn on. This throw is a danger to the diodes of the rectifier and can lead to the combustion of the fuses. Therefore, when the amplifier is turned on, the relay K2 is first closed (Fig. 12), and transformers are connected to the network through the restrictive resistors R1 and R2. At this time, the threshold for measured supply voltages is software installed equal to ± 38 V. If this voltage threshold is not reached during the set time, then the power process is interrupted. This may occur if the current amplifier consumed by the current circuit is significantly increased (the amplifier is damaged). In this case, the indication of the "UF" power supply accident is indicated.

If the threshold of ± 38 V is reached, the relay K3 is triggered (Fig. 12), which eliminates resistors from primary chains of the main transformers. Then the threshold is reduced to ± 20 V, and the microcontroller continues to monitor the supply voltages. If during the operation of the amplifier, the supply voltage drops below ± 20 V, the protection is triggered and the amplifier is turned off. Reducing the threshold in the normal mode of operation is necessary in order to the "prepires" of supply voltage under load, a false triggering of protection occurred.

Schematic scheme processor boards shown in Fig. 9. The basis of the processor is the AT89C51 type AT89C51 microcontroller of the ATMEL firm, which works on a clock frequency of 12 MHz. To increase the reliability of the system, a U2 Supervisor is applied, which has a built-in watchdog timer and a power monitor. To reset the watchdog timer, a separate WD line is used, on which a periodic signal is programmed. The program is constructed in such a way that this signal will be present only if the timer interrupt handler and the main program cycle is performed. Otherwise, the watchdog timer will restart the microcontroller.

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Fig. 9. Circuit diagram of the processor board.

The display is associated with the processor using an 8-bit bus (XP4 - XP6 connectors). The display of the display card registers uses C0..C4 signals, which are produced by the U4 address decoder. The U3 register is a latch of the younger address byte, only discharges A0, A1, A2 are used. The senior byte of the address is not used at all, which made it possible to release the P2 port for other purposes.

When you click on the control buttons, sound signals are generated. To do this, use the BPR line to which the transistor key VT1 is connected to the dynamic emitter HA1.

The main and right channels are connected to the processor board using XP1 and XP2 connectors, respectively. Through these connectors, the status signals of the protection system of the IOF current and protection against the constant component at the DCF amplifier output are fed. These signals are common to the left and right channels, their association is possible due to the outputs of the protection scheme with open collectors. OKL and OKR protection system readiness signals are separate through the channels so that the processor can identify the channel in which the protection scheme has worked. The ENB signal that comes from the processor to the protection system allows the switching on the load relay. This signal is common for two channels, which automatically synchronizes the operation of two relays.

TRR and TRL lines are used to read the thermometers installed on the radiators of the right and left channel, respectively. The temperature measured by thermometers can be displayed on the display if the corresponding indication mode is enabled. The maximum temperature value of two for the left and right channels is indicated. The measured value is also used for the program implementation of overheating protection.

Additionally, the XP1 and XP2 connectors have WUR, WIR, WUL and WIL signals that are used by the output power measurement circuit.

The processor board from the duty source through the XP3 connector is powered. 4 levels are used to power: ± 15 V, +12 V and +5 V. levels ± 15 V are disconnected when switching to duty mode, and the remaining levels are always present. Consumption from levels +5 V and +12 V in the standby mode is minimized due to software disconnection of the main consumers. In addition, multiple control logical signals arrive through this connector on the duty source of the power supply: PEN - controls the duty power source, Rex - includes the relay of external sockets, RP1 and RP2 - include the main power source relay, FAN - includes a fan. Nutrition of protection schemes that are located on the main boards are carried out from the processor board with the level of +12 V, and the power of the display board - the level of +5 V.

To measure the output power and 12-bit AD7896 type AD7896 type AD7896 is used to monitor power supply voltages. One channel ADC is not enough, therefore the U5 switch is used at the input (8-channel ADC, for example, type AD7888 would be applied. The data is read from the ADC in a sequential form. For this, the SDATA and SCLK (clock) lines are used. Starting the conversion process is performed by the START signal. As a support source and at the same time a voltage stabilizer, the ADC is used Ref195 (U7). Since in standby mode, the supply voltage ± 15 V is turned off, all logic signals are connected to the ADC through the R9 - R11 resistors, which limit the possible current throw when switching to duty mode and back.

Of the eight switch inputs, six are used: two for power measurement, four to control power voltages. The required channel is selected using AX0, AX1, AX2 address lines.

Consider power measurement scheme left channel. The applied scheme provides multiplication of current and load voltage, so the impedance of the load is automatically taken into account and the readings always correspond to the actual active power in the load. Through the resistor divisors R49 - R54, located on the main board (Fig. 5), the voltage from the current sensors (emitter resistors of the output transistors) enters the differential amplifier U8a (Fig. 9), which selects the current signal. From the output of U8A through the R17 trim resistor, the signal enters the input Y of the analog multiplier U9 type K525PS2. The voltage signal is simply removed from the divider and enters the input of the X analog multiplier. At the outlet of the multiplier, the R18C13 is installed, which selects a signal, proportional to quasipitic output power with an integration time of about 10 ms. This signal comes to one of the switch inputs, then on the ADC. The VD1 diode protects the switch input from the negative voltage.

In order to compensate for the initial displacement of the zero of the multiplers, when the amplifier is turned on (when the load relay is not turned on, and the output power is zero) there is a zero auto-calibration process. The measured displacement voltage for further work is deducted from the ADC readings.

The power in the left and right channels is measured separately, and the maximum value through the channels is indicated. Since the indicator should display both a quasipic and mean output power, as well as the indicated values \u200b\u200bmust be convenient for perception, measured using the ADC values \u200b\u200bare subject to software processing. The time characteristics of the power level meter are characterized by the integration time and the reverse time. For a quasipic power meter, the integration time is specified by a hardware filtering chain and is about 10 ms. The average power meter differs only by increased integration time, which is implemented programmatically. When calculating the average power, a moving average of 256 points is used. Reverse time in both cases is specified programmatically. For the convenience of reading the readings, this time should be relatively large. In this case, the reverse stroke of the indicator is implemented by subtracting 1/16 of the current power code once in 20 ms. In addition, the indication is carried out with peak values \u200b\u200bwithin 1.4 seconds. Since too frequent update indicator readings is badly perceived, the update occurs every 320 ms. In order not to miss the next peak and display it synchronously with the input signal, when the peak is detected, an extraordinary update of readings occurs.

As mentioned above, the mind uses common with a pre-amplifier remote controlwhich works in the RC-5 standard. The SFH-506 type remote control system receiver is located on the display board. From the output of the photodetector, the signal enters the SER (INT1) input of the microcontroller. Decoding RC-5 code is programmatically. The number of the system used - 0Ah, the "Standby" button has code 0CH, the "Display" button - 21H, the "MODE" button - 20H. If necessary, these codes can easily be changed, since the transcoding table is used, which can be found at the end of the source text of the microcontroller program.

On the display board (Fig. 10) There are two two-digit seven-segment indicators HG1 and HG2 type LTD6610E. They are managed by parallel registers U1 - U4. Dynamic indication is not used, as this can cause an increased level of interference.

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Fig. 10. Concept of indication board.

The U5 register serves to control LEDs. A restrictive resistor is included in consistently with each segment and with each LED. OC inputs of all registers are combined and connected to the PEN signal of the microcontroller. During the reset and initialization of the registers, this signal is in a state of high logical level. This prevents accidental ignition of the indication during transition processes.

On the display board, the SB1 - SB6 control buttons are also installed. They are connected to the data bus lines and to RET return line. VD1 diodes - VD6 prevent short circuit Data lines while pressing two or more buttons. When scanning the keyboard, the microcontroller uses the P0 port as a simple output port, forming running zero on its lines. At the same time the RET line is interviewed. In this way, the code is pressed by the button.

Next to the indicators under the common protective glass there is an integrated photodetector of the remote control U6. The signal from the output of the photodetector through the XP6 connector enters the SER microcontroller input (int1).

Duty source (Fig. 11) provides 4 levels at the output: +5 V, +12 V and ± 15 V. Levels ± 15 V in standby mode are disconnected. The source uses a small toroidal transformer, wound on a 2x20x25 mm core. The duty transformer has a large supply of power, as well as the number of turns on the volt selected more calculated. Thanks to these measures, the transformer practically does not heat up, which increases its reliability (it should work continuously during the entire service life of the amplifier). Winding data and wire diameter are listed on the diagram. Stabilizers voltage features do not have. The chips of stabilizers U1 and U2 are installed on a small total radiator. To turn off the levels of ± 15 V keys on the VT1 - VT4 transistors, which are controlled by the PEN signal coming from the processor board.

Fig. 11. Schematic circuit board of the duty power supply.

In addition to voltage stabilizers, the keys on the transistors VT5 - VT12 are installed on the duty source of the power supply source for the relay control and fan. Since the microcontrollers of the MCS-51 family during the reset signal, the ports are in a state of high logical level, all actuators should be included in a low level. Otherwise there will be false responses at the moment of power on or in the case of a watchdog timer. For this reason, single as keys cannot be applied n-P-N Transistors With OE or ULN2003 drivers chip and similar.

Relay, fuses and restrictive resistors are located on relay board (Fig. 12). Connecting all network wires is performed through screw terminal. Each main transformer, a duty transformer and an external sockets block have separate fuses. For safety reasons, external sockets are disconnected by two K1 relay contact groups that burst both wires. The main transformers have a removal from the middle of the primary winding. This removal can be used to obtain voltage 110 V to power other components of the complex. The apparatuses corresponding to the US standard are somewhat cheaper than multisystems, so they are sometimes found on our territory. On the relay board, there are points from where you can remove 110 V, but in the base version, this voltage is not used.

Fig. 12. Schematic circuit board relay.

Diagram of block connections on chassis amplifier Shown in Fig. 13. The secondary windings of the main transformers T1 and T2 are connected bridge rectifiers collected on VD5 diodes - VD12 type CD2997A. Filter capacitors with a total capacity of more than 100,000 μF are connected to the output of rectifiers. Such a high capacitance capacitors are necessary in order to obtain a low level of ripples and improve the amplifier's ability to play pulse signals. With the filter capacitors, the supply voltage is ± 45 B is supplied to the main amplifier boards. Additionally, there are low-power rectifiers collected on diodes VD1 - VD4, the output voltage of which is filtered with a relatively small time constant by condensers C1 and C2. Through resistors R1 and R2, the output voltage of these auxiliary rectifiers is fed to the protection schemes that are assembled on the main boosts of the amplifier. When multiple semiportions of the network voltage are dropped out, the output voltage of the auxiliary rectifiers falls, which is detected by the protection schemes, and the load relay is disconnected. At this time, the output voltage of the main rectifiers is still quite large due to the capacitors of a large capacity, so the transient process in the amplifier does not begin with the connected load.

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Fig. 13. Connection diagram of the amplifier blocks.

For power amplifier design and layout No less important than circuitry. The main problem is that the weekend transistors require an effective heat sink. With a natural cooling method, this is poured into massive radiators that become almost the main elements of the design. A common layout, when the rear wall serves simultaneously with the radiator, does not fit, since then the back there is no place to install the necessary terminals and connectors. Therefore, in the described mind, a layout with a side arrangement of radiators was selected (Fig. 14):

Fig. 14. The overall layout of the amplifier.

Radiators are somewhat raised (this is clearly seen in Fig. 4), thereby ensuring their better cooling. Basic amplifier boards are fixed parallel to radiators. This minimizes the length of the conductors between the board and output transistors. Another overall elements of the amplifier are network transformers. In this case, two toroidal transformers are applied, which are installed on each other in the overall screen of the cylindrical shape. This screen takes a significant part of the internal volume of the amplifier housing. The main rectifiers are installed on the overall radiator, which is located vertically at the back of the transformer screen. Filter capacitors are located below the amplifier chassis and closed with a pallet. There is also a relay fee. The duty of the power supply is fixed on a special bracket near the rear panel. Processor and display boards are located in the thickness of the front panel, which has a box cross section.

When developing an amplifier design, much attention was paid to the technological design and convenience of access to any node. In more detail with the layout of the amplifier can be found in Fig. 15 and 18:

Fig. 15. Location of the amplifier nodes in the assembled form.

The basis of the amplifier housing is aluminum alloy chassis D16t 4mm thick (4 in Fig. 18). To the chassis are attached radiators (1 in Fig. 18) which are erected from an aluminum plate or casting. The required area of \u200b\u200bradiators strongly depends on the operating conditions of the amplifier, but it should not be less than 2000sm 2. To facilitate access to the amplifier fees, radiators are fixed on the chassis using the loops (10 in Fig. 18), which allows radiators to pop up. In order for this that the wires input and output connectors do not interfere, the rear panel is broken into three parts (Fig. 4). The middle part is fixed with the bracket on the chassis, and the two side pieces are fixed on radiators. The connectors are installed on the side parts of the panel, which are folded together with radiators. Thus, the radiator assembly is a monophonic mind that is connected only with power wires and a flat control cable. In fig. 18 Radiators for clarity are collected only partially, and the rear panel is not disassembled.

Basic boards amplifier The radiators are also fixed on the radiators with the help of loops (12 in Fig. 18), which allows them to capture, getting access to the side of the soldering. The axis of rotation of the board passes through the holes for connecting the wires of the output transistors. This made it possible to practically not increase the length of these wires while simultaneously abandoned the fee. The upper attachment points of the boards are conventional threaded racks with a height of 15mm. The wiring of one-sided main boards of the left and right channel is made mirror (Fig. 16), which made it possible to optimize the compounds. Naturally, the mirror of the topology is not complete, as items are used, which cannot be simply located mirrored (chip and relay). The drawing gives an exemplary idea of \u200b\u200bthe Topology of Boards, the topology of all boards is available in the archive (see the download section) as files in PCAD 4.5 format.

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Fig. 16. Wiring of the main amplifier cards.

On each radiator 1 (Fig. 17) there is a smooth surface 2, which is processed after the blackness. On it, nine transistors 4 installed through ceramic pads 2.

Fig. 17. The design of radiators:

The studies have shown that the mica, and the more modern elastic gaskets, do not have sufficient thermal conductivity. The best material for insulating pads is a ceramics based on BEO. However, for transistors in plastic cases, such gaskets are almost never found. Pretty good results managed to get gaskets from hybrid chip substrates. This is a pink ceramics (unfortunately, the material is definitely not known, most likely something based on Al 2 O 3). To compare the thermal conductivity of different gaskets, a stand was collected in which two identical transistors in the T-220 case were fixed on the radiator: one directly, the other - through the underlying gasket. The current base in both transistors was the same. The transistor on the gasket dispelled the power of about 20W, and the other power transistor did not dissipate (the collector did not supply voltage). The difference in the falls of the B-e in two transistors was measured, and for this difference the difference in transition temperatures was calculated. For all gaskets used heat-conducting paste, without it the results were worst and unstable. The results of the comparison are presented in the table:

Output transistors are pressed with overlays 5, the remaining transistors are attached with screws. It is not very convenient, since the drilling of ceramic gaskets is required, which can be done only with diamond drills, and even then with great difficulty.

A thermometer 9 is installed next to the transistors. As the experience has shown, when the DS1820 thermometers attached to their body, it is impossible to have a large pressure, otherwise the readings are distorted, and it is very significant (it is better to glue with glue with high thermal conductivity).

Under the transistors on the radiator 6 is fixed. On the reverse side of this board, the conductors are missing, therefore it can be fixed directly to the surface of the radiator. The findings of all transistors are soldered to the grounds on the top of the board. The compounds of the board with the main board are made short wires that are depressed into hollow rivets 7. In order for the rivets not to close the radiator, it has a recess 8.

Basic toroidal transformers (7 In fig. 18) through elastic gaskets installed on each other. To reduce the filing from transformers to another equipment (cassette deck, for example), transformers are recommended to put in the screen from annealed steel with a thickness of at least 1.5mm. The screen is a steel cylinder and two caps pulled by a pin. To avoid the appearance of a short-circuited turn, the upper cover has a dielectric sleeve. However, if it is assumed to operate the mind on a large average power, then the ventilation openings should be provided on the screen or abandon the screen at all. It would seem, for mutual compensation of transformer scattering fields, it is enough to simply turn on their primary windings of anti-phase. But in practice, this measure is very ineffective. The field of scattering of the toroidal transformer, with the apparent axial symmetry, has a very complex spatial distribution. Therefore, the ransom contains one of the primary windings leads to a weakening of the scattering field at one point of space, but to strengthening to another. In addition, the configuration of the scattering field significantly depends on the load of the transformer.

Fig. 18. Basic amplifier nodes:

1 - radiators	12 - Loop Fastening Boards
2 - Basic boards of amplifier	13 - Board Fastening Rack
3 - playground on the radiator for installation of transistors	14 - Control cable connector (from processor board)
4 - bearing plate	15 - wire from the release of extra. Rectifier
5 - Front panel bearing plate	16 - Duty Transformer on Screen
6 - front panel of the box	17 - duty power supply board
7 - Basic transformers on the screen	18 - Radiator voltage stabilizers
8 - Radiator Diodes Rectifier	19 - Relay Control Wires
9 - Power supply to fees	20 - Rear Panel
10 - Fastening of radiators on the loop	21 - Output terminals
11 - Radiator mount bracket	22 - Input connectors

To the power transformer, the mind is presented by very stringent requirements. This is due to the fact that it is loaded on the rectifier with a very large filter capacitors. This leads to the fact that consumed from secondary winding The current transformer is pulsed, and the value of the current in the pulse is many times more than the average current consumed. To losses in the transformer remain low, the windings should be very small active resistance. In other words, the transformer must be designed for significantly greater power than the average is consumed. In the described amplifiers, two toroidal transformers were applied, each of which is wound on the 110x60x40 mm core from the E-380 steel tape. Primary windings contain 2x440

UMPs with a microcontroller control system
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