I need help with short circuit detector / electronic fuse.
So I'm making a variable power supply with an LM317 and I've decided to add a short circuit protection, I know the LM317 has an auto shutdown feature but I thought this would be a nice feature and it would allow me to leanr more about circuits.
The short detector is quite simple, It's a PNP transstor connected to the output. When the output is shorted the LM317 can't supply enough current and the load sucks everything it can, so it sucks the charge of the capacitor, causing the PNP transistor to activate and turn on the relay and the LED. This connects the PNP to ground, making it be permanently oopen until the circuit gets reset.
It works flawlessly from 16 to ~9 volts, but I go under ~9v (I don't know why) the PNP activates and the relay flickers very fast, I tried several things but none fixed the problem.
I have plenty of PNP nad NPN transistors so if you can come with a better and more stable design I would be able to try it, I'll be all the afternoon trying if I can figure this out and posting some updates.
Here's a video of how I want it to work.
Look at the image for more information.
Thanks in advance.