Best way to switch off this power supply

I’m working on a Nixie Tube clock and I plan on having it switch off at certain times. I was originally just going to send an unusable code to the decoder to turn them off until I just realized the little neon lamps are directly wired to the +170v. I was thinking it would just be more efficient to switch off the power supply to take care of the nixies and the lamps at the same time. I am using this 555 timer power supply. It will be supplying about 17-20ma but I wasn’t sure if the power supply itself uses up more current. I was wondering what the proper way of switching off this PSU would be. I figured I could just cut the +12v but I wasn’t exactly sure what things I need to consider to decide how I do that.


While it would be easy to switch the 9V input with two transistors, another way would be to put a transistor across Q2 and drive the base through a resistor from the arduino. When this transistor is on it will stop the circuit oscillation and so cut off the high voltage. Just check when you do this that the gate of the FET is at zero and so off.

I'll give that a try. Thanks.

why not just use the arduino to ground the reset pin. You would need to put a pull-up between vcc and the reset pin.


Because that would expose the arduino pin to the Vcc value when it is running. If this is higher than the arduino's supply it will zap the pin. You need a transistor to isolate the arduino from this voltage.