Hi everyone..
I'l tried to modify 350W computer power supply (under 20 eur).
Input is 220V~, gretz and capacitors makes DC.. Push-pull mosfets driving ferrite core transformer, about 40KHz frequency with pwm.
Base of this circuit is ka7500, similar TL494 chip. Active cooling with 8cm fan.
Output capacitors are removed, output shottky diodes too.
Output impedance is very low, and driving homemade neodium magnet+alu folly speaker. Thru low-pass filter, of course.
Vref DC input of tl494 is modulated with audio. Chinch and trimer pot.
...BUT...
why output power is not strong enough? Before changing this power supply given 25Amps on +5V, and now is ~20W audio maximum! Why?
Best regard.