I have a circuit with a, IC darlington chip that is used to bring approx 1 Amp of current to an LED. It is controlled by a (4%?) PWM pulse that goes at about 800hz.  Every time the circuit provides current to the LED, I get this ringing on my power supply. I tried numerous things such as using an inductor in series to try and suppress it, using big caps,  to even using external regulators.  I cannot seem to get rid of it. The only thing that really helped was the bypass caps (big and small) and putting a Schottky diode between the base and collector. However, I still get some ringing that effects other parts of my circuit. Any one else have any ideas I can try? Maybe I am going about this wrong?