bryanthehacker

modified 7 years ago

Simplest Class D Amplifier

974

1d 02:10:02

- High Power
- Variable Gain
- Voltage Feedback for a nice output signal
- High Efficency

-Transistor BD139 BD140
-Mosfet IRF540 IRF9540
-Ultra Fast Op Amp

published 9 years ago

thebugger

9 years ago

A very weird topology. I like it though. With an automatic error correction or something. Although I think there's a possibility for erratic behaviour. It doesn't only modulate the pulses width, but also their frequency at times. I don't know, but very nice. Me likey ;)

thebugger

9 years ago

I think it needs a pinch of hysteresis to limit thr maximum sampling frequency.

bryanthehacker

9 years ago

Yeah this circuit need more fixes , but it's f***ing crazy ahah !!

thebugger

9 years ago

Absofucking! Awesome circuit! Needs a pinch of hysteresis, but EC shows no solution when the hysteresis is low, it works when the hysteresis is super high, and that doesn't do us any good.

bryanthehacker

9 years ago

I add two .22 resistors to prevent high current peaks that can blow up the mosfets and two protection schottky diode.

2ctiby

9 years ago

50 v getting to the Mosfet gates..? are your z diodes wired correctly?...just wondering

bryanthehacker

9 years ago

Yes , measure the Vgs , it's 0 to 15v :)

bryanthehacker

9 years ago

Use a voltmeter between gate and source

2ctiby

9 years ago

Yes, I hadn't taken the min v of 35 from the max 50. Your output signal looks like a nice replica of the input too. Thanks.

thebugger

9 years ago

In my experience the output signal doesn't need to be super clean. Remember the speaker has inductance, and will clear out most harmonics itself. Moreover the speaker cannot reproduce signals with a higher frequency than 20Khz. So everything above it, gets mostly filtered. There are even some filterless class D amps, that use the speaker itself as th filtering component.

bryanthehacker

9 years ago

Mmm there is only a small bug... the gate voltage are not a perfect square wave , and in a small fraction of time all the two mosfet are actived , and i see a short circuit.

bryanthehacker

9 years ago

I will try this circuit on another simulator. And build it if works fine.

thebugger

9 years ago

Typically the MOS stage should be with one N-Channel MOS and one P-Channel MOS. This way you ensure that no matter what, one MOS will always be closed when the other is conducting.

hurz

9 years ago

"no matter what, one MOS will always be closed when the other is conducting" .... Buggzy, have you ever tried that in real? Or start first in simulation and see what will happend with your "no matter what...."

2ctiby

9 years ago

Just a little messing here ... http://everycircuit.com/circuit/5232141589282816

2ctiby

9 years ago

More messing around here.... http://everycircuit.com/circuit/5732389315149824

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.