Attached is my amplifier circuit schematics. It is laid out on a breadboard. There are two isolated stages - preamp and poweramp.
Each stage works great on its own. They go crazy when interconnected. I guess it is called motorboating effect.
The input waveform is severely distorted. The output waveform is worse. The power supply oscillates between 18 to 20 V, 0.8 to 0.4 amps at around 1.2 Hz (visually observed).
I have already added power supply AC drains (at the end of rails) and supply line resistors across the stages. They don't seem to help much. What else can be done?
Each stage works great on its own. They go crazy when interconnected. I guess it is called motorboating effect.
The input waveform is severely distorted. The output waveform is worse. The power supply oscillates between 18 to 20 V, 0.8 to 0.4 amps at around 1.2 Hz (visually observed).
I have already added power supply AC drains (at the end of rails) and supply line resistors across the stages. They don't seem to help much. What else can be done?