I'm designing a low power -5V supply circuit. How do I go about protecting voltage from going too negative? Like if the 7905 failed and decided to let -12V through to the output?
Normally, for a positive supply, I would use a polyfuse then a varistor across + and GND. Do varistors work on a negative supply? I googled but couldn't find the answer.
Here's an example of what I have so far. (Capacitance not shown).