High Power Half Bridge ClassD Amp (Prototype 2) Coming never? Maybe one day just for fun
This page is for problems, solutions and what was wrong.
When amp was on smps or transformer with +/-30Vdc there was no problems at all, over current worked. But after going to higher supply voltage of +/-47Vdc, amp started to act funny. When output voltage came around 32v on output, with 4 ohme load connected, start to put +47V on output (I don't have DC protection, so I had to turn off supply). When I have reconnected supply everything was OK. Later I found that it was enough just to disconnect the load.
So I started to look with scope and found that on piece of 10cm/4mm^2 wire that was going from supply's GND to amps GND had squerwave about 2Vpp @250kHz large on it !!! Later with help of Diyaudio.com I found out that output with high di/dt and dv/dt were interfering with input circuit, cousing amp to become unstable. It was proposed that I split supply for power and signal and take them from same points (main capacitors).
That I have done and tried. Amp still becamed unstable, but some where over 40v on output. Now main problem is that I don't have any ground plane on other side of board. Usage of SMD would help alot, making paths shorter than they are now.
Now my solution will be to make board with SMD and use ground plane on other side. This will allow me to make smaller board. Now I don't know if I will split GND on power and signal which would be connected on board OR have seperate wires for power/signal.
Pic of new board which is not complited :
