My switching power supply produces 5.4V DC, which then goes to a 3.3V linear regulator. An outlet is connected to the 120V, 60HZ power source, which is what is fed into my power supply. When I plug an electric razor in the outlet, I measure the voltage at the 3.3V regulator output, and I get 3.3V. When I turn the razor on, I still have 3.3V. When I turn the razor off, the oscilloscope triggers and I have a voltage spike from approx. +6V to -8V for about a split second, then I have 3.3V again.
I'm trying to get rid of this spike. Ideally I'd want to keep the voltage positive at all times. I have tried snubbing circuits, but I am not certain how to connect it.
Thanks.