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Attiny85 based PSU safety overrider

If you are using computer PSU as bench power supply you probably know this annoying feature when safety triggers and the only way to reset supply is to reattach green wire to ground. Safety is safety but what about convenience. Simple switch might work fine but Henry wanted more intelligent approach to solution.

So he used an Attiny85 microcontroller to take care of this. Simple circuit has a button input, status LED. As input it takes voltage from 5V red wire of PSU. Microcontroller is powered from purple wire of PSU which stays 5V when safety is triggered. And finally green wire is attached to MCU so it could control according to algorithm. Having microcontroller power he added several features selectable with single button. PSU can be turned on and off with simple press. If button is pressed and hold for loner time PSU safety features are overridden for mad scientist projects (beware of danger). Project code is written in Arduino style using MITs guide on putting Arduino in to Tiny MCU.

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