About a very very simple class D PA amp

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Hello

Here is a very very simple class D PA amp.

For sure this amp would have a high distortion. This is my first class D amp, but it is only for 100 to 300 w for PA only.

Is there any errors in this schematic, and is there any suggestions of simples modifications to made it a bit better ?

For Q3 I would use MJ2955 or for higher power MJ15004

How about a power mosfet for Q3 ?

Thank you

Bye

Gaetan

An externally hosted image should be here but it was not working when we last tested it.
 
There are much better ways to do a class D amplifier without much more parts or expending much more money.

Also, this output stage with bipolar transistors is not likely to produce much more than +/-1A reliably and is not efficient due to the voltage drop on the 1K resistors, it's designed the wrong way.

Do some research...
 
Pafi said:



Unfortunately it contains some errors. U1 Pin 15 and 16 swapped, left side of R3 should be connected to U1 Pin14.

Output DC level should be adjusted very precisely, carefully, without load.
Sorry about those mistakes; too quickly drawn image(original on paper;) ).

The +30V is actually PSU-s ground(not the amplifiers). Measuring the circuit is a lot easier this way.
Some pics: http://static1.album.ee/album/262631/50086439

Btw this version is the first one(perfoboard), just for practice, and uses ferrite in its output filter. First three os-pictures show heavy ringing, which was eliminated by ceramic caps in power rails(C10, C11, etc; other 3 os-pics).The second version uses double sided PCB and ferrite is changed to iron-powder one(T106-2).Cam is broken and I cant make more pics...
 
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