Two versions of a robust module capable of delivering high powwer for extended periods.  The Actrk400 uses 6 n-channel Mosfets in the output stage to deliver around 400 watts into 4 ohms while the Actrk600 uses 12 n-channel Mosfets in the output stage to deliver power in excess of 600 watts into 4 ohms.  One constructor has achieved almost 900 watts with the Actrk600 layout using 12 IRFP460 Mosfets.

20 Watts Power Amplifier circuit can be made ​​with an IC power amplifier LM1875. IC LM1875 is a single chip power amplifier from National. 20 watts audio amplifier with LM1875 is a low power amplifier with good quality to the room.


To assemble the amplifier 20 watts with IC LM1875 component is not needed much support. 20 watts power amplifier using LM1875 IC in this article using symmetrical power supply. The series of 20 watts audio power amplifier with IC LM1875 can be used as an experiment or first project for the reader, because it is simple and assembly of high success.

LM1875 amplifier circuit with the above may result in the strengthening of the voltage up to 27dB for each channel (1 channel 1 IC). Strengthening the voltage can be changed by changing the feedback that is R5 R (on the circuit above using R 22K). But the tension reinforcement can not be less than 20 dB because it can cause oscillation. For the power supply or power supply 20 watts power amplifier rngakaian with lm1875 can use travo 2-3A with CT.

Components of the above is one component of ic which is applied as a reinforcement. Power amplifier used in an audio signal in order to become more powerful and can be heard via a tool that is the speaker. But in each set must have a voice amplifier, voltage, power quality is different.
For the IC has the output power above 2 X 40 Watt with 8 Ohm output impedance. Supply voltage ranging from 18 Volt to 32 Volt.

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. The depth could be reduced to 10mm if the output capacitor is mounted at the speaker and the on-board electrolytics are mounted horisontally. Here are the typical performance figures that may be expected from the finished amplifer using a 3-ohm load with a 13.8-volt supply. I see no reason why the supply voltage cannot be increased a little to obtain more output power:

Parameter	Minimum	Maximum	Units
Supply voltage	8	15	volts
Output power	-	5.4	Watts
I/P for full O/P	30	4000	mV (RMS)
Noise O/P no I/P	-	0.0005	Volts RMS
Supply current (no-signal)	-	50	mA
Supply Current (Full O/P)	-	1.9	Amperes
3dB Frequency Response	42	34000	Hertz
6dB Frequency Response	21	62000	Hertz
Distortion at 2-watts	-	0.01	% (Vgain=10)

No heatsinking is required for the output transistors when running at a modest output level with either speech or music. A small heatsink should be fitted to the two TIP41 transistors if running a constant tone level. The heatsink could be bolted directly to the TIP41s without electrical isolation if the heatsinks are not going to touch anything. A heatsink with a 15-square surface area is all that is required. Here is the circuit of the amplifer.

This is an audio amplifier circuit based on IC, and IC were used that MPC563 with minimal output 6W, with impedance of 4 Ohm. Supply Voltage Minimum 4 Volt DC and a maximum voltage to 20 Volts DC. See him under this Scheme.