Cheap simple class D amp circuit to build.

[guitar_joe]

Can somebody please post me a link to a dead simple class D amp that could be built on a bread board.

I just want to build one to see how they work for educational purposes.

Any leads on this would be fantastic

cheers

 

[BWRX]

A fully discrete circuit or one based around a chip?

 

[guitar_joe]

i think fully descrete would be the best way to go
I know it's not good for performance but it's
mainly for educational purposes

 

[BWRX]

Fortunately you can have both

http://www.diyaudio.com/forums/showthread.php?s=&threadid=85389

 

[guitar_joe]

cool. cheers

 

[alfsch]

look, my cheap-d :
http://sodfa.so.ohost.de/content/images/11_End-MK1-1b.sch.pdf

 

[v-bro]

Not discrete, but I've seen people build 41hz.com AMP6 on a breadboard...

It is pretty cheap...

 

[luka]

Hi alfsch

How does your circuit work?

 

[alfsch]

its a simple selfosz. amp, "ucd" style...
here test with 5khz,1w ,8 ohm:

 

[luka]

Hi alfsch

Could you post some waveforms of the amp. Like output with no signal,... any

 

[alfsch]

what do you expect?? its like any d-amp...
see (in german, but lokk at the pics http://sodfa.so.ohost.de/include.php?path=forum/showthread.php&threadid=146

without signal : about 3vss sine at 250khz out, the carrier

with full signal, a pic:

 

[luka]

Hi

Thanks, just wanted to see, my is on hold for now

 

[luka]

Hi

Do you still have simulation for LTSpice? I don't know how to put LM393 or any other fet in. So with that elements that you had, simulation is running, but Fpwm is ~100kHz.

 

[alfsch]

ok, i made a zip for you...
unpack to directory, where simu-file xx.asc is/should be

works now?

 

[luka]

Hi

Lm is still missing. it said can't find symbol comp2

 

[alfsch]

ok. here comp2...

 

[luka]

Hi

Jup now it works, thanks. Do you think if I make the circuit, put +/-47Vdc for supply and use 4 ohm speaker, will it put out 200w+ ??

PS: why is there more current going through upper fet?

 

[luka]

Hi

I have see that someone had something called power calculator for LTSpice, do you have it, or where could I find it?

 

[alfsch]

P=U*U/(2*R) , for U=Umax, so 200w /4 ohm = +- 40v supply

dont worry, if currents are not 100% like ideal theory, this is a sim,
in real world , for optimum performance, you have to tune the gate resistors anyway, because depending on the c-gate of your actual mosfets timing will change;
with 100v mosfets, you should not go up to the +- 50v limit, some safety margin is ...good for long life of mosfets...so +- 40v is maximum

for power calc you need to have a secret element in the circuit, i use the lt1076, with is doing nothing useful otherwise,;
start run, then go menu->simulate-> eff.calc. -> mark start
let it run some time, stop or run hole sim.time
then menu->show-> eff.report -> show on shemat.
you see eff calc in circuit

 

[fdeck]

ok. here comp2...

I did not look closely, but are the power supplies on the LM393 fixed at +/- 10 V in the model for that part?

Nice job. The simulation works great.