TDA8927/TDA8929 Audio Amplifier 2x80W

TDA8927/TDA8929 general description:

The TDA8927 is the switching power stage of a two-chip set for a high efficiency class-D audio power amplifier system. The system is split into two chips:

TDA8927J/ST/TH; a digital power stage in a DBS17P,
RDBS17P or HSOP24 power package
TDA8929T; the analog controller chip in a SO24package.

With this chip set a compact 2 × 80 W audio amplifier system can be built, operating with high efficiency and very low dissipation. No heatsink is required, or depending on supply voltage and load, a very small one. The system operates over a wide supply voltage range from ±15 up to ±30 V and consumes a very low quiescentcurrent.

TDA8927/TDA8929 features:

• High efficiency (>94%)
• Operating voltage from ±15 to ±30 V
• Very low quiescent current
• High output power
• Short-circuit proof across the load, only in combination with controller TDA8929T
• Diagnostic output
• Usable as a stereo Single-Ended (SE) amplifier or as a mono amplifier in Bridge-Tied Load (BTL)
•  Electrostatic discharge protection (pin to pin)
• Thermally protected, only in combination with controller TDA8929T.

TDA8927/TDA8929 applications:

• Television sets
• Home-sound sets
• Multimedia systems
• All mains fed audio systems
• Car audio (boosters).

TDA8927/TDA8929 circuit diagram:

TDA8927/TDA8929 layout and pcb:

МР7720 Audio Amplifier 2x30W

      Modern integrated class D UMZCH combine seemingly incompatible: high efficiency and low THD. This article describes the basic principles of Class-D amplifiers and describes the line chips UMZCH American firm MPS (Monolithic Power Systems). Recently, the power amplifier circuitry (UMZCH) have developed two contradictory directions: Improvement in the subjective quality of sound reproduction, usually by reducing the efficiency (COP) of the amplifier; Increased efficiency of the amplifier and reduce its size while maintaining high quality performance. The first direction is characterized by using the output stages UMZCH powerful field-effect transistors and vacuum tubes (Hi-End), often working in class A. The second direction is characteristic of wearable and automotive audio equipment. It is in realization of this direction are widely used amplifiers class D, and high-quality sound reproduction apparatus stationary class D is most commonly used in amplifiers for the subwoofer. There are five major classes of modes of active elements (transistors or tubes). This class of operation modes A, B, AB, C and D. Recall their features.

Class A mode

of operationactive element (transistor or bulb) is open throughout the period of the signal. Class A power amplifiers introduce minimal distortion in the amplified signal to have a very low K11D. They are used in one-and two-stroke potaktpyh UMZCH for midrange and tweeters, which is especially important that the level of harmonic distortion was low. Class A amplifiers - the most expensive.

Class B operation mode

active element (transistor or tube) is only open one half cycle of the input signal. Class amplifiers have high efficiency.but THD them much higher. Commonly used in two-stroke UMZCH srsdnschastotnyh for speakers and speaker mid-bass.

Operation mode class AB

active element (transistor or bulb) and this mode is open one half-full and some of the other half-cycle of the input signal. Mode class AB - a cross between classes A and B. Class AB amplifiers have a higher efficiency. than Class A amplifiers, but contribute to the signal harmonic distortion less than Class B. This is the most common class of mass UMZCH.

Mode of operation of class C

Class C - is the work of transistors with a small amplitude of the voltage locking lower than the bias voltage. In this case, the amplitude of the audio signal is less than the bias voltage. In this state, the transistor conducts only the upper portion of the positive half, greatly distorts the signal. Therefore, audio amplifiers, this class is not applicable.This mode transistors has a high efficiency (about 85%).

Class D operation mode

in mode class D converts the input signal into rectangular pulses of equal amplitude, the duration of which is proportional to the value of the signal at any given time (eg, PWM - Pulse Width Modulation). Active elements of the output stage to operate at the same switching mode and have two states: a transistor or a locked or fully open. Class D amplifiers have a maximum efficiency, as main energy loss pas weekend powerful keys occur until the moment when in the open position and minimal energy loss will be less than the lower the resistance of the public key.Conventional Class D amplifiers have an efficiency of over 90% and large enough THD (about 10%), and application of new technologies (know-how of the producers) to reduce THD to fractions of a percent. This significantly expanded the scope of class D in modern UMZCH.

The concept is simple UMZCH Class D

Basic principles of UMZCH Class D

concept is simple UMZCH Class D shown in bottom

It consists of a pulse width modulator (PWM) on the transistor Q1, a strong push-pull transistor switch Q2, Q3, and a lowpass filter (LPF) which filters out high frequency components of the pulse current through the loudspeaker. Divider na resistors R1 and R2 will set the offset voltage of Q1 and the symmetry of the whole scheme. R3 - load resistor transistor Ql. R4, C4 - thermostabilization emitter circuit of the transistor. C1 - filter capacitor voltage. C5, R5, L1. C6 - a lowpass filter (LPF). C7 - decoupling capacitor. The composition of Class D amplifier also includes a generator of a triangular or sawtooth. The frequency of this oscillator is usually in the range of 200 ... 600 kHz. Swipe "blade" of the generator and the gain stage to Q1 are chosen so that the output transistor switches Q2 and Q3 are alternately opened until when the voltage saturation "saw" through zero. Stress diagram explaining the operation of the scheme. beep input otsugstvuet pas. "Saw * is symmetric, and na emitters of transistors Q2 and Q3 form a symmetrical square wave, square wave. When submitting pa amplifier input signal LF "Saw" will shift up or down. Change points unlocking transistors and as a consequence, the duration of the output pulses and pauses between them. These parameters will vary according to the law of the input low-frequency (audio) signal. The resulting pulse signal with a variable duty cycle pulse-called imiulspym or PWM sigialom and process to obtain it - shirotpo-width modulation (PWM). PWM sigpal contains LF component. form modudiruyuschy repeating signal. If the PWM signal from the output transistor switches to pass through the LPF, then he will miss this component to the speaker and to suppress the high-frequency components of the PWM sigpala. Due to incomplete suppression of the HF-sostavlyayuschsy AC voltage on the speaker will be slightly indented, you can see enlarged fragment pas to the lower graph in  . Irregularity decreases with increasing frequency PWM generator, improved quality of the LPF and the use of certain know-how, which carefully guard Manufacturers chip amplifiers class D.

Class D amplifiers using bipolar transistors are gone. The foundation of modern UMZCH Class D are powerful keys pas MOS transistors are characterized by high performance and low resistance channel open. When using such transistors in key mode achieves a high efficiency. Two practical schemes UMZCH Class D MOS transistors and operational amplifier are given in [1]. The real boom in the use mode class D UMZCH began with the appearance of such specialized chips as ZXCD1000 firm Zeiex | 2 |, and several others. These chips are called driver amplifiers class D. They contain a PWM generator with "Saw" frequency 2200 kHz and provide control of external keys on MIS traizistorah. Many of these drivers can drive four external output keys pas MOS transistors included bridge. The next stage in the development of UMZCH Class D was the creation of chips that integrate not only the driver but also the keys pas weekend MIS traizistorah. It is to such chips are MR7720, MR7731 and MR7781 firm MPS (Monolithic Power Systems). All are monophonic. About rated output says penultimate figure in the name: MR7720 - 20 W, MR7731 - 30 W, MR7781 - 80 watts. Peak output power of these chips twice. Consider the features and switching circuits each of them.

MR7720 IC is available in a SOIC8 (SMD) and PDIP8, which have 8 pins and the same pinout, or, as they say now, raspipovku. UMZCH this chip has a memorial 20W load resistance of 4 ohms and a supply voltage of 24 V. Frequency Response -20 Hz .... 20 kHz. It has an efficiency of 90% with non-linear distortion less than 0.1% for the whole frequency range and output power of 1 W (0.06 ... 0.07% to 1 kHz). Supply voltage 7.5 ... 24 V chip embedded in the bottom of the output key pas MOS transistors, which are connected in series on Nutrition (half-bridge).

Schematic diagram UMZCH Class D chip MR7720

Circuit of the chip that is very similar to the OS or UMZCH on chips that operate in the usual modes of classes A, B or AB. Integrated circuit U1 MR7720 has a differential input (pins 1 and 2), a positive (neivertiruyuschy) conclusion in this scheme is used as an input offset voltage, which sets the mode of the chip, and most importantly - the symmetry of the circuit. Bias voltage to neivertiruyuschem input (pin 1) should be equal to half the supply voltage, it is formed divider R3, R2. Capacitor C2 blocks the output AC voltage. It should be noted that the asymmetry of the circuit can cause an increase in nonlinear distortion and even overheating of one of the output switches and the output circuit of the system. The input signal is applied to the inverting input of circuits (terminal 2) via a capacitor C1 and a current limiting resistor R1. In position C1 firm - chip developer recommends using a ceramic capacitor types NPO, X7R, X5R or equivalent types. Voltage gain circuit is defined by the resistors R1 and NFB circuit R4 and can be calculated by the formula: 

KU = R4/R1.

To increase the amplitude of the output pulses chip used on conventional two-stroke known transformerless amplifier circuit to increase efficiency with voltage boost capacitor C7, which is connected between the output (pin 7) and the input voltage boost circuit (pin 5). The capacitor C7 is selected in the range of 0.1 ... 1 uF. To protect the internal circuitry chip overload C7 connected in parallel with the zener diode D2 stabilization voltage of 6.2 V. For separation of the amplified signal and suppress high frequency components of the pulse in the load to the output (pin 7) is connected SFF consisting of choke L1 and capacitor C8. Capacitor C9 - isolating. Schottky diode D1 suppresses the induction currents and EMF emissions arising from the shift points in the L1 output switches when both keys are locked. PWM frequency transformation given feedback circuit R4, NW, and these denominations in the scheme it is 600 kHz. At a higher frequency increases power loss, and at least - non-linear distortion. C4 - NFB capacitor for high frequency. Capacitors Sat, C5 - decoupling filter feeding. To eliminate the passage of impulse noise on the supply lines capacitor C5 must be provided between the terminals 6 and 8 of the chip, and as close as possible to these conclusions. Simply work UMZCH this can be explained as follows. Input through Cl, R1 is supplied to the inverting input of the chip (output 2). This leads to a change in duty cycle duration and frequency of 600 kHz at the output circuit (pin 7) to change the law of the instantaneous value of the input signal and the appearance of the output signal amplified LF component, repeating the form input, which is through the LPF L1, C8 and separation capacitor C9 is supplied to the loudspeaker. Add to this can only be that the input and output signals in antiphase.

MR7731 chip comes in a TSSOP20F SMD, who has 20 pins and a metal pad on top for thermal contact with the heat sink. Rated power on the chip UMZCH MR7731 is 30 watts at 4 ohms load resistance and supply voltage 16 V. Frequency 20Hz .. "20 kHz. Efficiency of 90% at an output power of 5 watts. Harmonic distortion less than 0.1% for the whole frequency range with output power of 1W. Supply Voltage 7.5 - .24 B. chip 'built on four key output MOS transistors, which included the bridge. Feature mono UMZCH bridge is that they have two, usually equal to the output of amplifier channel keys that include half-bridge. Ie MR7731 chip contains two channels, similar in structure to the chip MR7720. Sol that these channels operate in antiphase, and the load (speaker) without dividing capacitors connected between the outputs of these channels, as a constant voltage at each output terminal is equal to half the supply voltage. For antiphase control switch channels normally used by the "master - slave» (Master - Slave), ie both amplifiers are included on the input signal sequentially 

C1, C2 - blocking capacitors. R1. R2-voltage divider signals, L1, NE and L2, C4-LPF

For this integration, both channels must be an inverting amplifier. The signal on the second channel is output from the first through the divider Rl, R2  or the limiting resistor.

Schematic diagram UMZCH Class D chip MR7731

Typical circuit diagram UMZCH Class D chip MR7731 is shown in Fig , and pin assignment of this chip is shown bottom

Pin Number Designation Appointment

1 NC Not used

2 PIN1 Non-inverting input of channel 1. Used as an input offset voltage (reference voltage)

3 NIN1 Inverting input channel 1

4 AGND1 Housing analog part 1

5 NC Not used

6 EN1 Enable input channel 1. High - MS enabled. Low - off

7 NIN2 Inverting input of channel 2

8 PIN2 Non-inverting input of channel 2. Used as an input offset voltage (reference voltage)

9 AGND2 Housing analog part 2

10 EN2 Enable input for channel 2. High - MS enabled. Low - off

11 NC Not used

12 BS2 Input voltage boost circuit channel 2

13 VPP2 Input voltage of channel 2 (7.5 ... 24 V

14 SW2 Output channel 2

15 PGND2 Housing supply circuits 2

16 NC Not used

17 BS1 Input voltage boost circuit channel 1

18 VPP1 Power supply input channel 1 (7,5 ... 24)

19 SW1 Output channel 1

20 PGND1 Housing supply circuits 1

      Sort out the details of the appointment on the chip UMZCH MR7731 scheme (Fig. ). Bias voltage to neiver-commuting inputs of both channels (pins 2 and 8), equal to half the supply voltage divider formed by R2, R5. Capacitor 09 bypasses these findings AC voltage, and capacitors C54 and C41 set the PWM frequency conversion of the 1st and 2nd channels respectively. These capacitors should be located as close to the terminals, near which they are drawn in the diagram. C53 - supply filter capacitor, and the C55 and C42-decoupling capacitors, which also should be placed as close as possible to the terminals, near which they are drawn. The input signal is applied to the inverting input of the channel 1 (terminal 3) via a coupling capacitor C35 and a current limiting resistor R16. The voltage gain of the channel is defined by 1 chip resistors chain DUS R14hR16, and channel 2 - Values ​​R44 and R34. NFB HF channel 1 through capacitor C29. and Channel 2 - through C34. Capacitor C37 - this capacitor voltage boost channel 1, and C22 - capacitor voltage boost channel 2. They increase the efficiency of the amplifier. Parallel to these capacitors connected diodes D13 and D15 with a voltage of 6.2 V. The strong stabilizing output sound stands out in Fitch at the outputs of channels 1 (L4, C47) and 2 (L3, C43) and goes to the speaker. Fitch suppress high frequency components of the PWM pulse signal at the outputs of the chip and do not miss them in the load. Schottky diodes D6, D8 quenched induced currents and EMF emissions arising coils L3 and L4 switch points in the output switches when they are all locked. These coils should be rated at 2.6 A. Each channel has its own enable input EN1 (pin 6) and EN2 (pin 10).With a low voltage level on these findings the chip will be in the standby mode, when high - in operation. MR7781 chip comes in a SOIC24 SMD, which has 24 output and a metal pad on top for thermal contact with the heat sink. Memorial power on-chip mono UMZCH MR7781 80 watts at 4 ohms load resistance and supply voltage of 24 V. Frequency range 20 Hz to 20 kHz ..... 95% efficiency at an output power of 80 watts. Harmonic distortion less than 0.1% for the whole frequency range with output power of 1W. Supply Voltage 7.5 - .24 B. chip built on four key output MOS transistors, which included the bridge. MR7781 chip has two equal channel amplifier with differential inputs and output MIS keys that included half-bridge. This device contains two amplifier channels, each of which ends on the half-bridge MOSFETs. All this reminds MR7731, but unlike this chip, typically inclusion MR7781 scheme is used, which can be called a parallel-series connection of amplifier channels (see Fig ). In this scheme, the input signal directly to the inputs of both amplifier channels. Moreover, one channel it enters the non-inverting input, and in the other - an inverting. Therefore, the upper and lower speaker terminals are applied at the same amplitude but anti-phase voltage signals that can be seen from the graphs shown in the diagram ( Fig ). The ratio of resistances limiting resistor R1 and resistor divider circuits DUS R2, R3, R4, R5 determine the gain circuit. Divisors through R2, R3 and R4, R5 are defined as the bias voltage at the inputs and made ​​negative feedback (NFB) at a constant voltage, which stabilize the mode amplification channels, ie these divisors set dc output channels equal to half the supply voltage, and by CCA to maintain them.

Simplified diagram UMZCH Bridged output (with parallel-serial control)

C1 - decoupling capacitor, 

R1 - limiting resistor, 

R2, R3 and R4, R5 - divisors circuits 00C DC and AC voltage, 

L1, C2 and L2, NW - LPF

MR7781 chip has a complex internal organization than the above circuit. This is indirectly confirmed by the number and pin assignments chip, as shown bottom .

Pin assignment chip MR7781

Pin Number Designation Appointment

1 DR1 Control output voltage of the low voltage channel 1

2 NC Not used (recommended to connect pin 1 or 3)

3 GND Corpus internal modulator

4 AI2 Non-inverting input of channel 2

5 BI2 Inverting input of channel 2 (input AUDIO HSE)

6 MO2 Internal PWM output + channel 2 (open-drain)

7 SHDN2 Enable input for channel 2. Active level - low

8 BS2 Input voltage boost circuit channel 2

9 GND Housing supply chain channel 2

10 SW2 Output channel 2

11 V + Input voltage PWM (7,5 ... 24)

12 M2 Input signal PWM driver stage of channel 2

13 DR2 Control output voltage of the low voltage channel 2

14 NC Not used

15 V + Input voltage of channel 2 (7.5 ... 24 V)

16 MO1 Internal PWM output channel 1 + (open-drain)

17 AI1 Inverting input of channel 1 (input DUS)

18 BI1 Non-inverting input of channel 1 (input AUDIO)

19 SHDN1 Enable input channel 1. Active low level +

20 BS1 Input voltage boost circuit channel 1

21 GND Housing supply circuits

22 SW1 Output channel 1

23 V + Power supply input channel 1 (7,5 ... 24)

24 M1 Input signal PWM driver stage channel 1

Typical circuit diagram UMZCH MR7781 on a chip is shown in Fig . The input signal is applied to the terminals 5 and 18 chip through limiting resistor R20 and capacitor C25. Resistors R3, R5, R7, R17, R19, R21, R12, R8 and capacitors Sat, C24, C9, C15 includes chain NFB DC and AC voltage. These chains set the gain chip and constant voltage equal to half the supply voltage, at the midpoint, ie outputs channels UMZCH bridge (pins 10 and 22 chips).Capacitor CIO in channel 1 and channel 2 S18a - Capacitors voltodobav matches that are needed to improve the efficiency of the amplifier.

Schematic diagram UMZCH Class D chip MR7781

LI, C2, L2, C2, C13, R2, C5, R18, C23 - it details the SFF, which is passed to the speaker audio signal and suppress pulse HF component of the PWM signal. SFF coils L1 and L2 must be rated at 5 A. The optimal frequency PWM conversion IC MR7781 is 400 kHz. It is determined by the capacitance of the capacitor C that is connected between the differential input pin of this chip (connected between the two terminals 5, 18, 4, 17). EMF emission quenching and induction currents in the coils L1 and L2 LPF moments in the switching output switches when they are all locked up, carried Schottky diodes D1 and D5.

Each channel has an enable input (active low). Pin 19 (SIIDN1) - this is the enable input channel 1 and pin 7 (SIIDN2) - enable input channel 2. These terminals are connected together. High level (inhibit signal) is generated using the parametric stabilizer R6, D3. With this level of power is turned off and is in MUTE, which is characteristic of low current consumption (

To obtain such a low power consumption mode MUTE, on-chip voltage regulators integrated low-voltage parts and circuit switching them. Control signals are output from this circuit chip via terminals 1 (DR1) and 13 (DR2), and then through the switching diodes D2 and D4 received at terminal 20, respectively (BS1) and 8 (BS2). Moreover, TT high level control signal output 13 (DR2) opens key on the bipolar transistor Q1. Through the transistor supply voltage supplied to the junction of resistors R1 and R11. Do chip MR7781 there are four interesting conclusions. This conclusion 16 (MOl), 24 (Ml), 6 (M02) and 12 (M2). MOl and M02 - it outputs PWM appropriate channels, a Ml and M2 - is key inputs output circuits. Conclusions MO and M with the same numbers are interconnected. In addition, outputs MO1 and MO2 are open drain. The pull-up resistor (external load) connected between these terminals and the voltage at the emitter of transistor Q1, - it is already known resistors R1 and Rl 1. C1 - supply filter capacitor, and capacitors NW, C12, C16, C8, C10, C14 and C18 - decoupling. To improve the outcome and reduce the interference is recommended to install them as close as possible to the corresponding terminals of the chip. To eliminate the characteristic UMZCH click for inclusion in the scheme established capacitors C7 and C9.

To ensure stability and repeatability circuit resistors R3, R5, R7, R17, R19, R21 and R12 should be 1% tolerance. The same shall be allowed, and a resistor R6.

THD indicated in the table, achievable and guaranteed only at a frequency of 1 kHz at the output power of 1W. With increasing frequency and power it rises. Dependence THD chip MR7720 from power (at a frequency of 1 kHz, 24 V supply voltage and load impedance 4 ohms) is shown in Fig, and the frequency of the signal (at 24 V supply voltage, load resistance of 4 ohms and power 19.6 W) -

In conclusion, I want to note that there are several varieties of PWM amplifiers. First, it is power "Class T" pulse width modulator which not only changes the duty cycle, but the frequency of the PWM output signal. Secondly, the so-called power "class N», information about which can be found in [3]. It also amplifier operating in key mode, but combined with the power supply unit.

STK465 Audio Amplifier 2x30W

STK465 general description:

     A amplifier of acoustic frequencies can be manufactured with discernible materials, despite is known so much the difficulties of finding of materials, what the problem of regulations. These difficulties are overcome relatively easily if we find amplifier in form completed.

Completed STK465 is an amplifier of acoustic frequencies that offers qualitative output, using minimal exterior elements. Substantially he is one of big completed force. Has a line pins and incorporated metal surface for adaptation in cooler. The provision pins in a line, facilitates the placement completed in the end printed and his support in cooler. The circuit functions in a big range of benefits of catering, from 20V as 60V, and it attributes 30WRMS, when the tendency of catering is above 50V and composer resistance of loudspeaker is the 4 or 8 Ohm. The catering should be symmetrically.

     When it functions with tendency 56V then the tendency will be ± 28V as for the ground. With this recommended tendency of catering, the attributed force is 30 WRMS in charge 8W. The price of deformity is acceptable and oscillates around in the 0,08% for force of expense from 1W until 30W. Curve response his it is extended from 10Hz and reaches 100 KHz, with divergence 0dB and -3dB respectively, measured in force 1W. Using evolved techniques, completed amplifier STK465, can minimise the deformities even in highest levels of force. Other characteristically that determines the completed circuit they are: the wide area and the high aid.

     STK465 is drawn to be constant, when it functions in conjunction closed bronchi with big gain. As all the amplifiers, thus and this, under certain unfavourable conditions, can turn in oscillations. These oscillations have as result of returning in the same phase from the exit in the entry, or from bad designing PCB, or from bad choice of corridors in the circuits of entry. When you draw a printed circuit, it is important to return the current of charge and the current of signal of entry in the ground, via different corridors. Generally, positive is the charge it is connected directly in pin the catering and in particular in common pin electrolytic the catering. If entry and charge are connected directly in the 0V via the same road, then are created retroactions, what have as consequence oscillations and the deformity. To you we propose maintaining as much as possible smaller the cables of ground 0V and the capacitors of unharnessing, so that are limited the results of self-induction and resistance of lines of copper PCB. Sometimes the oscillation is owed in big length drivers between entry and expense, particularly if these have big length and the complex resistance of source are high. Can anticipate the oscillation that is owed in long wirings, adding capacitor from 50 - 500pf between pins entry. For the low deformity, important role plays also the placement of conductors of catering. This should be kept as much as possible more far from the wiring of entry, so that is deterred thus the not linear catering in the entry of IC. STK 465 does not have system of thermal protection, so that are avoided the thermal elations. If the temperature of JC reaches in high price, then the amplifier changes the polarisation of rung of expense. If the temperature is increased, then in order to is ensured the operation it should you grow cooler. The amplifier functions with catering of double polarity. In form 1 we see the electronic circuit of amplifier that Is based on the STK 465.

STK465 circuit diagram:

STK465 Circuit diagram

     The circuit is stereo and has two channels of amplifier in a nutshell. It is a formal designing that develops positively all the particularities completing. Concretely, we observe that the not inverting entry completed (pins 2 and 15, for each channel), is supplied from divider of tendency, which ensures tendency from the tendency of expense completing. At the same time with the entry in each channel, exists a capacitor 470rF, which achieves the unharnessing, in that it concerns the AC components of high frequency, while en line a capacitor 1mF allows in the amplifier to be supplied from desirable flourish acoustic frequencies, fence simultaneous the continuous component. Bronchi unharnessing it is realised with the help of networking of two resistances 33KW and 330W and a capacitor 100mF, which finally ensures factor of aid equal with 100. Finally, at the same time with the exit exists networking RC (0,1mF - 4,7 Ohm) that it attends to the minimisation of phenomenon crossover. The amplifier can be supplied from a line of double polarity. Still it can function under a wide region of tendencies (±10V as ±28V). The requirements of current depend from the force of expense and it can they begin from 120mA up to 1A. It is very important the catering to be sufficiently unharnessing, so that is avoided imports of annoying noises.

For the realisation of manufacture you are consulted the forms 2 and 3 that portray the PCB and placement of materials in this. Does not exist a dangerous element in the manufacture that it should him you are careful particularly, so much at the soldering, what at the use. Be careful the electrolytic capacitors, the placement cooler completed and naturally the polarity of lines of catering. One still directive in what it concerns the catering: good it is it is used power supply with big capacitors standardisation or still better stabilised.

STK465 pcb

STK465 layout

STK465 part list:

R1 = 1K

C1 = 1uF/35V

R2 = 3,3K

C2 = 470pF

R3 = 100

C3 = 100uF/60V

R4 = 330

C4 = 100uF/60V

R5 = 3,3K

C5 = 10uF/60V

R6 = 1K

C6 = 47uF/60V

R7 = 0,33

C7 = 8,2pF

R8 = 33Κ

C8 = 0,1uF

R9 = 4,7

C9 = 1uF/35V

R10 = 1Κ

C10 = 470pF

R11 = 3,3Κ

C11 = 100uF/60V

R12 = 100

C12 = 100uF/60V

R13 = 330

C13 = 10uF/60V

R14 = 3,3Κ

C14 = 47uF/60V

R15 = 1Κ

C15 = 8,2pF

R16 = 0,33

C16 = 0,1uF

R17 = 33Κ

R18 = 4,7

IC1 = STK465

LS1 = Speaker 40W 8 or 4 Ohm

Original article sourse http://iq-technologies.net

NE555 Ultrasonic Pest Repeller Circuit

This circuit uses two transistors and one IC (555 timer IC) to produce a pulsating ultrasonic frequency. Transistors Ql and Q2 are connected in a direct-coupled oscillator. The frequency of that oscillator is set by capacitor CI. The oscillator output is taken from the emitter of Q2 to pin 7 of IC1. Transistor Ql is an npn transistor, and Q2 is a pnp transistor. The signal of pin 7 on IC1 causes the output signal appearing on pin 3 to be modulated or varied by the audio frequency developed by Ql and Q2. The IC itself is connected as a stable multivibrator with a frequency that is determined by C3.

Capacitor C3 sets the basic frequency to be well above the human hearing range (ultrasonic). The combined modulated ultrasonic frequency appears on pin 3 of IC1, where it is coupled by capacitor C4 to the piezoelectric transducer.

NE555 Ultrasonic Sound Source

Using two NE555 timer IC devices, this circuit generates either pulsed or continuous ultrasonic signals. The values of CT for both pulse rate and ultrasonic frequencies can be calculated this way. SPKR is a small hi-fi tweeter.

NE555 Ultrasonic Sound Source

MJ11015 & MJ11016 Guitar Amplifier 60W

Guitar Amplifier general description:

     This design adopts a well established circuit topology for the power amplifier, using a single-rail supply of about 60V and capacitor-coupling for the speaker(s). The advantages for a guitar amplifier are the very simple circuitry, even for comparatively high power outputs, and a certain built-in degree of loudspeaker protection, due to capacitor C8, preventing the voltage supply to be conveyed into loudspeakers in case of output transistors' failure.

The preamp is powered by the same 60V rails as the power amplifier, allowing to implement a two-transistors gain-block capable of delivering about 20V RMS output. This provides a very high input overload capability.

Guitar Amplifier features: 

Sensitivity: 35mV input for 40W 8 Ohm output42mV input for 60W 4 Ohm output
Frequency response: 50Hz to 20KHz -0.5dB; -1.5dB  40Hz; -3.5dB  30Hz
Total harmonic distortion 1KHz and 8 Ohm load: Below 0.1% up to 10W; 0.2%  30W
Total harmonic distortion 10KHz and 8 Ohm load: Below 0.15% up to 10W; 0.3%  30W
Total harmonic distortion 1KHz and 4 Ohm load: Below 0.18% up to 10W; 0.4%  60W
Total harmonic distortion  10KHz and 4 Ohm load: Below 0.3% up to 10W; 0.6%  60W
Treble control:+9/-16dB 1KHz;  +12/-24dB 10KHz
Brightness control:+6.5dB 500Hz;  +7dB  1KHz; +8.5dB @ 10KHz
Bass control:-17.5dB 100Hz ; -26dB 50Hz; -28dB @ 40Hz

Guitar Amplifier circuit diagram:

Guitar Amplifier circuit diagram

Guitar PreAmplifier circuit diagram:

Guitar Amplifier notes:

• The value listed for C8 is the minimum suggested value. A 3300µF capacitor or two 2200µF capacitors wired in parallel would be a better choice.
• The Darlington transistor types listed could be too oversized for such a design. You can substitute them with MJ11014 (Q3) and MJ11013 (Q4) or TIP142 (Q3) and TIP147 (Q4).
• T1 transformer can be also a 24 + 24V or 25 + 25V type (i.e. 48V or 50V center tapped). Obviously, the center-tap must be left unconnected.
• D1 and D2 can be any Schottky-barrier diode types. With these devices, the harmonic modifier operation will be hard. Using for D1 and D2 two common 1N4148 silicon diodes, the harmonic modifier operation will be softer.
• In all cases where Darlington transistors are used as the output devices it is essential that the sensing transistor (Q2) should be in as close thermal contact with the output transistors as possible. Therefore a TO126-case transistor type was chosen for easy bolting on the heatsink, very close to the output pair.
• R9 must be trimmed in order to measure about half the voltage supply across the positive lead of C7 and ground. A better setting can be done using an oscilloscope, in order to obtain a symmetrical clipping of the output wave form at maximum output power.
• To set quiescent current, remove temporarily the Fuse F1 and insert the probes of an Avo-meter in the two leads of the fuse holder.
• Set the volume control to the minimum and Trimmer R3 to its minimum resistance.
• Power-on the circuit and adjust R3 to read a current drawing of about 30 to 35mA.
• Wait about 15 minutes, watch if the current is varying and readjust if necessary.

Guitar Amplifier partlist:

R1__________________6K8 1W Resistor 

R2,R4_____________470R 1/4W Resistors 

R3__________________2K 1/2W Trimmer Cermet 

R5,R6_______________4K7 1/2W Resistors 

R7________________220R 1/2W Resistor

R8__________________2K2 1/2W Resistor

R9_________________50K 1/2W Trimmer Cermet 

R10________________68K 1/4W Resistor 

R11,R12______________R47 4W Wirewound Resistors 

C1,C2,C4,C5________47µF 63V Electrolytic Capacitors 

C3________________100µF 25V Electrolytic Capacitor 

C6_________________33pF 63V Ceramic Capacitor 

C7_______________1000µF 50V Electrolytic Capacitor 

C8_______________2200µF 63V Electrolytic Capacitor (See Notes) 

D1_________________LED Any type and color

D2________Diode bridge 200V 6A 

Q1,Q2____________BD139 80V 1.5A NPN Transistors 

Q3_____________MJ11016 120V 30A NPN Darlington Transistor (See Notes) Q4_____________MJ11015 120V 30A PNP Darlington Transistor (See Notes) SW1_______________SPST Mains switch 

F1__________________4A Fuse with socket 

T1________________220V Primary, 48-50V Secondary 75 to 150VA Mains transformer (See Notes) PL1_______________Male Mains plug 

SPKR______________One or more speakers wired in series or in parallel Total resulting impedance: 8 or 4 Ohm Minimum power handling: 75W

Guitar PreAmplifier partlist:

P1,P2______________10K Linear Potentiometers 

P3_________________10K Log. Potentiometer 

R1,R2______________68K 1/4W Resistors 

R3________________680K 1/4W Resistor 

R4________________220K 1/4W Resistor 

R5_________________33K 1/4W Resistor 

R6,R16______________2K2 1/4W Resistors

 R7__________________5K6 1/4W Resistor 

R8,R21____________330R 1/4W Resistors 

R9_________________47K 1/4W Resistor

 R10_______________470R 1/4W Resistor 

R11_________________4K7 1/4W Resistor 

R12,R20____________10K 1/4W Resistors 

R13_______________100R 1/4W Resistor 

R14,R15____________47R 1/4W Resistors

 R17,R18,R19_______100K 1/4W Resistors 

C1,C4,C5,C6________10µF 63V Electrolytic Capacitors

 C2_________________47µF 63V Electrolytic Capacitor 

C3_________________47pF 63V Ceramic Capacitor

 C7_________________15nF 63V Polyester Capacitor

 C8_________________22nF 63V Polyester Capacitor 

C9________________470nF 63V Polyester Capacitor

 C10,C11,C12________10µF 63V Electrolytic Capacitors 

C13_______________220µF 63V Electrolytic Capacitor

 D1,D2____________BAT46 100V 150mA Schottky-barrier Diodes (see Notes) Q1,Q3____________BC546 65V 100mA NPN Transistors 

Q2_______________BC556 65V 100mA PNP Transistor 

J1,J2___________6.3mm. Mono Jack sockets 

SW1,SW2___________SPST Switches

Mixed connection to combined acoustic amplifiers

Amplifier these recorder can be used in two ways - as a two-channel bridge with a maximum power of 2x25 W or as with a conventional four-load connection and "virtual ground". Power in this case is 4h7Vt. The most famous member of this family - Sony 1253/1853. To work with a subwoofer also need to use a dual-channel configuration.

Fig.1.

Selecting the connection type, as in the previous case, be subject to the sensitivity of heads. A variant for capacitors C1, C2 act as HPF. They may be waived if the application heads provide undistorted reproduction of lower frequencies. Branch constant component produced internal capacitors radio. However, for option B necessarily the presence of two high-pass and low-pass filter for the stereo for the total channel. Their mission - to eliminate the parallel operation of heads at low frequencies. Since the impedance at low frequencies is almost equal to their heads DC resistance, lack of filters can lead to overload the amplifier, designed for a 4 ohm load. For stereo used first order filters (C1, C2), for the total - the second (C3L1R1). 

Another variant of the mixed load connection, but within one amplifier channel. It is convenient to connect two or three-way speaker system. LF-head bridging is used, and for the MF / HF or HF - the usual. Mode switch is set to the position for four-configuration. 

Fig.2.

Dependence of the power supplied to the heads of fader position is shown in ris.2.b. In the process of regulatory power to the pavement maximum load decreases by 6 dB (4 times), because in the end positions fader scheme reduces to the usual ("left without a signal" shoulder amplifier acts as a "virtual ground"). Note that in the zone of the joint action of the heads, they are parallel-connected, but because these frequencies are affected by the growth of the load impedance due to the inductance of the voice coil, the amplifier is not really an overload occurs.

Original article sourse cxem.net