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Showing posts from March, 2014

Speaker indicator

With this indicator you can see how much power an amplifier delivers. The circuit uses a LM 3915, the logarithmic variation of the known LED VU meter IC LM 3914. The circuit is connected directly to the speaker output of the amplifier, and the power state of 0.2 watts to 100 watts. The sensitivity of the circuit can be varied with R1. The basic settings are shown in the table. R1 = 10 k (see text)R2 = 10 kR3 = 390 ΩR4 = 2.7 K?C1 = 22 V μF/25LED1-LED10 = LED (color of choice)IC1 = LM 3915

Microphone amplifier

The preamplifier amplifies the output signal of a microphone, so that it can be. The further amplified by a power amplifier The circuit provides an output signal line. With two transistors, it is not difficult to build such a circuit. The amplifier produces little noise. In the shown embodiment, the circuit is suitable for microphones 500 and 600 Ω. 200 Ω R1 microphones should be reduces to 220 Ω and C1 should be increased to 4.7 uF. The gain is set by R2. If the average declared value of 22 K? Can be used. The maximum gain is about 200times. R1 = 470 ΩR 2 = 22 K?R3 = 12 K?R4 = 47 kR5 = 820 ΩR6 = 100 ΩR7 = 1 kR8 = 100 kC1, C4 = 2.2 V μF/16C2 = 47 V μF/16C3 = 470 nFT1 = BC 549CT2 = BC 547B

Microphone Preamplifier

This is a good pre-amplifier for microphones that can be. Used in, for example, mixing consoles The circuit operates with a dual op-amp type NE 5532. The amplifier must be adjusted. Simply plug the power and control over P1 such that half the supply voltage (6 V) on pin 3 of IC1 state. P2 is then adjusted to the desired volume. R1 = 8,2 kWR2, R4, R5, R6 = 10 kWR3 = 1 kP1 = 4.7 K?P2 = 100 kC1, C2, C4, C6 = 10 uFC3 = 470 nFC5 = 100 nFIC1 NE = 5532

Phono/line adapter

In older amps usually have a phono input is available. Today, it is used less and less, and therefore it would be useful if the input can be. Used as line input With this circuit it is. the circuit is actually an attenuator and a filter. The signal is attenuated to the level of a phono-receiving element, and filtered to the RIAA equalization is undone in the amplifier. On 'in' is the line signal, and is connected to the phono input 'from' the amplifier. R1 = 1 M 1%R2 = 82% 1 K?R3 = 1 k 1%C1-C4 = 1 nF 1% Styroflex

Peak Indicator

This indicator can be used, or to see if you can get the sound output. Damaged speakers with P1 lets you set the limit at which D1 LED lights. The potentiometer is 100k here, you can experiment. Themselves with other values ​​if you could turn a logical port on the LED or opto coupler would use, you can turn it so that the signal between the preamp and power amp would fall away. Or that the signal to the speakers with the aid of a relay would be turned OFF.
R1 = 680 ΩR2 = 1.2 K?P1 = 100 k linearlyB1 = 4 x B250C1000 or 1N4003D1 = LEDT1 = 2N3904

Amplifier circuit TDA 1524A

Description This amplifier can control the volume, balance and tone controls take over. The circuit operates a specially designed IC, LM 1036. The advantage is that few external components are necessary, and that may be, which are cheaper. Used for controlling monopotmeters speaks scheme for itself. S1 loudness can be adjusted. In the position shown, the loudness. Moreover, the IC TDA 1524A Philips same capabilities.
Circuit Diagram
Part list: R1-R4 = 47 kP1-P4 = 47 kC1 = 47 uFC2, C3 = 470 nFC4, C5, C16 = 10 nFC6, C7 = 10 uFC8, C9 = 390 nFC10-C13 = 220 nFC14, C15 = 4.7 uFIC1 = LM 1036

VU meter

This circuit can control analog moving coil meters, for use as a VU meter. The circuit is left connected to the line terminals of the amplifier. VU meter works pretty simple. T1 and T2 increase the signal strength. The signal is then rectified by the two diodes and applied to the meter. The capacitors C3 and C4 ensure that the voltage is slightly flattened and the meter responds less quickly.  After building the circuit, it must be calibrated. For this purpose, the VU meter connected to a tone generator which delivers 0.3V at 1000 Hz. Then P1 is fully open, that is to say that the wiper of P1 is located at the entrance. Then P2 is so cut that regulates the meter full deflection. P1 is then adjusted so that meter reads 0.5 mA (= half the maximum).  For a stereo VU meter circuit to be built twice.
R1 = 1 MR2 = 820 ΩR3 = 2,2 kohmP1, P2 = 100 kC1 = 330 nFC2 = 22 uFC3 = 1 uFC4 = 470 uFT1, T2 = BC 547BM1 = 1 mA meter

Subwoofer filter LM 741

Description for Subwoofer filter LM 741:
     If you like I want some more bass in your stereo, you can switch a subwoofer there. This is a speaker that only reflects the bass. Below is a circuit to ensure that the subwoofer gets really only the bass.  This circuit is used between the signal source (mixer, CD player) and the amplifier. It is an active filter, better than passive filters which are generally mounted behind the amplifier. The circuit is mono because the bass for both channels are equal. The human ear can not yet determine the direction of this bass.  The first 741 is used as a mixer amplifier. The gain is adjustable with P1. Then, the signal is applied to a second of the order Butterworth-filter. C A(C1 + C2) and C B (C3) can be calculate using the following formulas: where F k , the crossover frequency (the frequency at which filter stops the transmission of sound), pi = 3.1416, R = R3 = R4, F k in Hertz, and C. F. As shown, the filter is now set at 240 Hz. , the supply…

Subwoofer Amplifier 40W

Description This amplifier delivers massive power and uses one IC and two power transistors. The circuit consists of an amplifier IC (a TDA 2030A) and a power stage consists of two transistors.  Amplifier can be powered with an asymmetrical supply voltage of 12 to 44 V.

Circuit Diagram:

Part-list: R1-R3, R7 = 100 K?R6 = 8,2 kWR4, R5, R8, R9 = 1.40 Ω 1%R10 = 1 ΩC1 = 470 nFC2 = 10 V μF/63C3 = 4.7 V μF/63C4, C5, C7 = 220 nFC6 = 2200 V μF/50C8 = 1000 V μF/50D1, D2 = 1N4001T1 = BD712 or BD912T2 = BD711 or BD911IC1 = TDA2030ALS = speaker - 4/8 ΩCooling = Fisher SK08/75

Ultra-low quiescent current AF power amplifier

Power Amplifier 300W

POWER OUTPUT:200W rms/8 ohm 310W rms/4 ohm800W rms/8 ohm (Bridge mode) FREQUENCE RESPONSE  20HZ-20KHZ +/-0.5dB  INPUT SENSITIVITY  1V for 200W/300W  HUM AND NOISE  -105dB  THD  <0.1%  DAMPING FACTOR  65

Part list: R1-19= 1Kohm 5WR34-35= 0.1ohm 5WC14-17= 100uF 100VR2-3= 4.7KohmR36-43= 39ohmC15= 100nF 250V polyesterR4-5= 22ohmR37-42= 5.6Kohm 1WQ1-2-3BC547R6-14= 10KohmR38-41= 220ohm 5WQ4-5-6= BC557R7-8= 1KohmR39-40= 0.1ohm 5WQ7-11-12= BD140 or BC640R9-23*=10K ohmR44-45= 0.1ohm 5WQ8= BC549R10= 10ohm *see circuit sch.R46= 4.7ohm 2WQ9-10-15= BD139 or BC639R11-13= 2.2KohmR47= 100ohmQ13-14= MJ15004R12= 22KohmC1= 2.2uF 25VQ16-17= MJ15003R15-16= 22ohmC2-6= 330pF ceramicTR1= 2K2 TrimmerR17-18=  4.7KohmC3-8= 100uF 100VF1-2= 5A Fuse FastR20-25= 390ohmC4-9= 100nF 250VD1-3= 5.1V 0.5W ZenerR21= 6.8KohmC5= 100nF 100V polyesterD2= 62V/5W Zener or 47v and 15V in seriesR22=  4.7KohmC7= 100uF 25VD4-5= 1N4004R24-26-33= 220ohmC10= 1.5nF 100V polyesterL1=10 turns diameter 1mm in 15mm diameter tubeR27-32= 100o…

Audio amplifier 16 W

All resistors are 5 or 10 percent tolerance, 1/4-watt all capacitors are 10 percent tolerance, rated 35 volts or higher this circuit provides 16 watts of amplification. it is built using two LM383 power audio.

U1 U2LM383 8 watt audio amplifier icR1, R3220 ohm resistorR2, R42.2 ohm resistorR51 megohm resistorR6100k audio taper potentiometerC1, C710uf electrolytic capacitorC2, C5470uf electrolytic capacitorC3, C4, C60.2uf ceramic capacitorSPKR14 to 8 ohm speaker (up to 8 inches diameter)

4 watt audio amplifier circuit

I have recently included a page about AF amplifers for use with Homebrew rigs. In this I mentioned that I may include a practical one-watt circuit, complete with PCB foil and layout. Here it is, but I have taken the liberty of engineering it to provide 4-watts of AF output and with a frequency response almost suitable for Hi-Fi applications.

The circuit is very simple and incorporates darlington output transistors that will provide more than enough output current than is needed to drive a 3-ohm speaker. The gain may be pre-set for a variety of input levels, making it suitable for amplifying computer and cassette-deck Line-output levels. The input level is also suitable for use with the TDA7000 receiver. All components are easily available and I will shortly be making this project available as a kit. Naturally, the project will be built on a PCB which will also be available separately. Here is the first PCB, assembled and working.

The completed unit is 60mm x 75mm and only 30mm deep. …

Subwoofer Amplifier

The fins were added to a simple flat aluminium panel, and are made from 20 x 20 x 3mm aluminium angle. Their purpose is threefold - they improve the performance of the plate as a heatsink (although this is not necessary with the BP4078 PWM amp), they make the panel a lot more rigid, and provide essential protection for the volume control and phase switch. It also looks better IMO - it looks like it means business, rather than looking like one of those wimpy 50W plate amps you see advertised. Complite, original article sourse and right reserverd here

Power amplifier 65W with HEXFET

A medium power amplifier that is characterized by a lot of good sound quality, but simultaneously is very simple in the construction. full article here

Telephone Headphone Amplifier

Compact, inexpensive and low component count telecom head- set can be constructed using two readily available transistors and a few other electronic components. This circuit is very useful for hands-free operation of EPABX and pager communication. Since the circuit draws very little current, it is ideal for parallel operation with electronic telephone set. Working of the circuit is simple and straightforward. Resistor R1 and an ordinary neon glow- lamp forms a complete visual ringer circuit. This simple arrangement does not require a DC blocking capacitor because, under idle conditions, the telephone line voltage is insufficient to ionise the neon gas and thus the lamp does not light. Only when the ring signal is being received, it flashes at the ringing rate to indicate an incoming call. The bridge rectifier using diodes D1 through D4 acts as a polarity guard which protects the electronic circuit from any changes in the telephone line polarity. Zener diode D5 at the output of this b…

Loudspeaker as a Microphone

This circuits allows you to use a cheap loudspeaker as a microphone. Sound waves reaching the speaker cone cause fluctuations in the voice coil. The voice coil moving in the speakers magnetic field will produce a small electrical signal. The circuit is designed to be used with an operating voltage between 6 and 12 volts dc. The first transistor operates in common base mode. This has the advantage of matching the low input impedance of the speaker to the common base stage, and secondly has a high voltage gain. The second stage is direct coupled and operates in emitter follower. Voltage gain is slightly less than unity, but output impedance is low, and will drive long cables. Speech quality is not as good compared to an ordinary or ECM microphone, but quite acceptable results can be obtained. Speaker cones with diameters of 1 inch to 3 inches may be used. Speaker impedance may be 4 ohm to 64 ohm. The 8.2 ohm resistor value may be changed to match the actual speakers own impedance.

Stereo balance tester

Description The meter will show volume and tone control balance between left and right stereo amplifiers. For maximum convenience the meter is a zero-center type. Resistors are five percent or better and the diodes a matched pair. Optimum stereo level and phase balance occurs for matched speakers when the meter indicates zero. If the meter indicates either side of zero, the levels are not matched or the wires are incorrectly phased. Check phasing by making certain the meter leads are connected to the amplifier hot terminals and the common leads go to ground. Circuit Diagram

Stereo Circuit Balance Meter

Description When L R signals are equal, no output is present from Ul, and pin 6 is at a steady 4.5 V. Unbalanced audio causes the LEDs to vary in brightness,which causes a difference that corresponds to unbalance between channels. Circuit Diagram

Amplifier circuit with Tone Control

Description A Motorola TCA5500 or TCA5550 can provide a stereo preamplifier system with tone controls. This circuit provides a gain of about 10X, a 14-dB tone-control range, a 75-dB volume control range, and it can operate from 8 to 18 Vdc. IC2 provides 15 V for ICl, and the input of IC2 can be supplied from the power amplifier`s power supply (+) rail. Dl and R5 should be used if over 30 V input will be used. Circuit Diagram

Stereo balance meter 2

Description     Outputs from each channel are fed to the two inputs of ICl connected as a differential amplifier. IC2 and 3 are driven by the output of ICl. Output of ICl is connected to the noninverting inputs of IC2 and 3. If the output of ICl approaches the supply rail, the outputs of ICs 2 and 3 will also go high, illuminating LED3. This would happen if the right channel were dominating. If the left channel was dominant, the outputs of ICs 2 and 3 would be low, illuminating LED1. If the two channels are equal in amplitude, the outputs of ICs 2 and 3 would be high and low respectively, lighting up LED2. 
Circuit Diagram

Stereo balance meter

Description Play any stereo disc or tape and then set the amplifier to mono. Adjust left and right channel balance until meter Ml indicates zero; then the left and right output level are identical.
Circuit Diagram

Guitar treble boost

Description Ql is connected as an emitter follower in order to present a high input impedance to the guitar. C2, being a relatively low capacitance, cuts out most of the bass, and C3 with RV1 acts as a simple tone control to cut the treble, and hence the amount of treble boost can be altered.Q2 is a simple preamp to recover signal losses in C2, C3, and RV1.
Circuit Diagram

Baxandall Tone-Control Audio Amplifier

Description This circuit exploits the high slew rate, high input impedance, and high output-voltage capability of CA3140 BiMOS op amp. It also provides mid-band unity gain with standard linear potentiometers.
Circuit Diagram

Tone control circuit

Description A simple single-transistor circuit will give approximately 15 dB boost or cut at 100 Hz and 15 kHz respectively. A low noise audio type transistor is used, and the output can be fed directly into any existing amplifier volume control to which the tone control is to be fitted Circuit Diagram

Automatic Level Control Circuit

Description  The rectifier input is tied to the input. This makes gain inversely proportional to input level so that a 20-dB drop in input level will produce a 20-dB increase in gain. The output will remain fixed at a constant level. The circuit will maintain an output level of 1 dB for an input range of +14 to -43 dB at 1 kHz. Circuit Diagram 

Active crossover circuit with TL074

Circuit Description An audio source, like a mixer, preamp, EQ, or a recorder, is fed to the input of the Electronic Crossover Circuit. This signal is either AC or coupling, depending on the setting of switch 51, the non-inverting input of buffer amplifier Ul-a, a section of a quad BIFET, low amp TL074 noise made by Texas Instruments op. This stage has a gain of 2, and its output is distributed to both a low pass filter made by R4, R5, C2, C3, and Uld op-amp, and a high-pass filter made by R6, R7, C4, C5, and op amp ULC. These are12 dB / octave Butterworth filters. The response of the Butterworth filter was chosen because it gives the best compromise between the damping and phase.

Guitar Effect Circuit

This is a circuit I have designed for guitar effect builders, I was very unsatisfied with the way everyone was using just a plain old double pole double throw click switch for the bypassing. Most of the time it was very scratchy sounding using that method and I experienced loud pops in my amplifier when switching from straight through to effect. Observing my "Boss" pedals and how they were switched on and off I figured there must be more to it. It took me only about 4 hours to design and test this circuit, It works very well and I'm really satisfied with it so I'll be using it in all the effect pedals I build. It's a very clean bypass both electronically and mechanically.
How it works: the first stage in the schematic is a 4011 nand gate chip set up as a debounced switch to give the logic pulses from the switch to the flip flop. The second stage is the flip flop, this is a 4027 JK flip flop set up in toggle mode, this controls the switching of the 401…

High Voltage Solid-State Circuits for Tube Guitar Amplifiers

Circuit Description
The IRF820  MOSFET has a  voltage rating of  500v, it should  work well in  preamp stages of  most tube amps. The 100 ohm  resistor is there  to suppress H.F.  oscillations. If  IRF820 is  physically close  to the 12AX7  plate, you  probably won't  need it. You can see how the MOSFET is equivalent to a triode: Source/Cathode; Gate/Grid; Drain/Plate

You cannot use the MOSFET as a direct replacement for a typical tube gain stage. The MOSFET will not "self bias" like a typical cathode-biased tube stage.The MOSFET is an "enhancement device" while a triode is a "depletion" device. In this circuit, it is not necessary to use a heatsink on the IRF820. You can if you want.

Guitar Reverb Effect

The guitar input stage is a class A amplifier with adjustable bias. A 2N3906 PNP tranistor is used for a low noise design on this stage. The output of the preamp stage is sent to three places: the output mixer amp, the reverb driver amp, and the input clipping detector.
The reverb driver amp consists of a phase inverting push-pull circuit made from dual sections of a 5532 high quality audio op-amp. This provides a voltage swing of approximate twice the supply voltage to the reverb impedance matching transformer, allowing higher power transfer. The 100 ohm resistor is critical for insuring a clean drive signal, without it, the op-amps can saturate when driving the transformer, producing unwanted distortion.
The transformer matches the impedance of the driver amplifer to the reverb driver coil and allows a dual phase driving signal to power a reverb coil with one grounded side. The transformer is a standard "70 volt" audio line transformer that is often found on PA…

Subwoofer amplifier TDA7293


Multipower BCD technology
Very high operating voltage range (±50 V)
DMOS power stage
High output power (100 W into 8 Ω
THD =10%, with VS = ±40 V)
Muting and stand-by functions
No switch on/off noise
Very low distortion
Very low noise
Short-circuit protected (with no input signal applied)
Thermal shutdown
Clip detector
Modularity (several devices can easily be connected in parallel to drive very low impedances)


The TDA7293 is a monolithic integrated circuit in Multiwatt15 package, intended for use as audio class AB amplifier in Hi-Fi field applications, such as home stereo, self powered loudspeakers and Topclass TV. Thanks to the wide voltage range and to the high output current capability it is able to supply the highest power into both 4-Ω and 8-Ω loads. The built-in muting function with turn-on delay  simplifies the remote operation avoiding on-off switching noises. Parallel mode is possible by connecting several  devices and using pin11. High output power can  be delivered …

Amplifier Circuit Diagram Class D

200W Power Amplifier

This 200W power amplifier circuit using IC STK 4050.  STK 4050 is a power amplifier module is very powerful, because the IC is already a module then only needed a little extra components to build a reliable 200W Power Amplifier. Here is a picture series of Power Amplifier ICs 200W use STK 4050 complete with its power supply:

800W Power Amplifier MOSFET


In this blog we talk about audio amplifiers and I would like to get more detail information about them. An audio power amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 - 20 000 Hz, the human range of hearing) to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain.       If we talk about the history of amplifiers, we can say, the audio amplifier was invented in 1909 by Lee De Forest when he invented the triode vacuum tube. The triode was a three terminal device with a control grid that can modulate the flow of electrons from the filament to the plate. The triode vacuum amplifier was used to make the first AM radio. Early audio power amplifiers were based on vacuum tubes (also known as valves), and some of these achieved notably high quality (e.g., theWilliamson amplifier of 1947-9). Most modern audio amplifiers are based on solid state devices (transistor…

100W Bipolar Power Amplfier

Circuit Description:
This is a plain 100 watt power amplifier designed to subsist (relatively) tranquil to build next to a reasonable fee. It has a better performance (read: musical quality) than the standard STK module amps with the intention of are used in the sphere of almost all throng advertise stereo receiver manufactured at the moment. at what time I originally built this contraption, it was since I considered necessary a 100 WPC amp and resolve not fancy slightly money. The design is essentially a standard format, and I’m positively present are business entities with the purpose of are alike. To my knowlwdge, it is not an exact emulate of a commercial entity, nor am I aware of one patents on topology. on behalf of practiced builders: I am aware to many improvements and adjustments can come to pass made, but the theory was to keep it straightforward and have to achieve-able by anybody who is a circuit, and has not the patience to do a sloppy mission. If alone crave Bipolar Tran…

Analog circuit

Analog circuit is a electronic systems with a continuously variable signal, in contrast to digital electronics where signals usually take only two different levels. The term "analogue" describes the proportional relationship between a signal and a voltage or current that represents the signal. The word analogue is derived from the Greek word ανάλογος (analogos) meaning "proportional".

Electronic circuit

An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another. Circuits can be constructed of discrete components connected by individual pieces of wire, but today it is much more common to create interconnections by photolithographic techniques on a laminated substrate (a printed circuit board or PCB) and solder the components to these interconnections to create a finished circuit. In an integrated circuit or IC, the components and interconnections are formed on the same substrate, typically a semiconductor such as silicon or gallium arsenide. Article:


Type of electrical engineering circuit

Electronic circuit, active electronic components connected in a circuitAnalog circuit Mixed-signal integrated circuitDigital circuitSynchronous circuitPrinted circuit board (PCB)Series and parallel circuitsTelecommunication circuitCircuit diagramBalanced circuitIntegrated circuitAsynchronous circuit LC circuit ...

10W Class D power amplifier

The TDA7480 is a class D audio amplifier assembled in Power DIP (PDIP20) package, specially designed for high efficiency applications, capable of 10W output power at a load of 8w/4w and a total harmonic distorsion of 10%. Requires a split-supply (max. ±20V).

The main selling point of this amplifier is the very low dissipated power compared to normal class AB amplifiers. Only a small "on board" copper area heatsink is required for normal operation. The IC has built-in stand-by and mute feature, overvoltage protection, short circuit protection and thermal overload protection.

The output of the amplifier is a high frequency square wave (~100Khz), rail to rail, with variable duty cycle. To obtain the audio signal, the output must be low pass filtered. The preamplifier provides the voltage gain of the overall amplifier. The second stage is the class D power stage, with a gain 1.5. The class D amplifier stage is done with a multivibrator. With no signal it generates a 50% duty cycle…

Audio Amplifier LM386

Audio Amplifiers with LM386

The LM386 is a versatile, small power amplifier designed for use in low voltage consumer applications. The gain is internally set to 20 to keep external part count low, but with the addition of an external resistor and capacitor between pins 1-8 the gain can be set to any value from 20 to 200.

The inputs are ground referenced and the output automatically biases to one-half the supply voltage. The quiescent power drain is only 24 milliwatts when operating from a 6 Volt supply, making the LM386 ideal for battery operation.

To make the LM 386 a more versatile amplifier, 2 pins (pin 1 and 8) are provided for gain control. With pins 1 and 8 open the internal 1.35k resistor sets the gain at 20 (26 dB). If a capacitor is placed between pin 1-8, bypassing the built-in 1.35k resistor, the gain will go up to 200.

If a resistor is placed in series with the capacitor, the gain can be set to any value from 20 to 200. Gain control can also be done by capacitively coupli…