Finally got myself three of those tiny e-bay 500W class D amps to play with. Was giving it a 1KHz tone burst and watching it on the scope because my dummy load isn't big enough to handle continuous tone. Then I dropped it down to 30Hz for 3 cycles every 1 second. Why is the first half cycle (yellow output, blue input) a bit weak and have a bit of DC offset? Could the input coupling cap be causing that if it is not big enough? And what about the overshoot when the tone burst stops? The amp is inverting but I flipped the output trace over.
Attachments
I was curious enough to set up a sim in LTSpice and yeah, this laggy and overshooting waveform does seem to be caused by too low a value input coupling cap. I managed to get quite similar to your picture with 3k and 3uF as the input components. I note the IRAUDAMP7S schematic has 22uF for the input coupler.
- Status
- Not open for further replies.