I'm learning Arduino and electronics. I've built ten small projects on Beginning Arduino by Michael McRoberts. This is the last project I did.
I had a lot of fun with it. I found that I would a bench power supply to do other projects or electronic devices.
I converted a ATX power supply to a bench power supply lately after spending 15 some hours. It had 3.3V, 5V, 12V, and negative 12V output. It was working fine until I connected a cheap 12V USB charger without any load in reverse polarity with two jumper wires. When I connected the USB charger in right order, smoke came out from the charger. I thought only the charger was damage.
Right after that I connected a 12V cooling fan for PC to 12V for testing. The fan was running smoothly for few minutes then suddenly the power supply went to standby mode (only green LED was turned on.)
Turning on and off the power supply few times to troubleshoot out of anxiety finally triggered the house circuit break. I knew the power supply has at least one 2A fuse. So when I checked the fuse on the circuit board in multimeter, it's 0.3 ohm.
Why the fuse was fine when the power supply was draining 50A current at 220VAC?
I put the power supply away to salvage parts later on. But, I'd like to replace damage components if it's not hard to do during spare time as learning experiences.
Below are few photos:
12V output test. ^^
Now it's officially dead. I put one 10W power resistor, four resistors for red and green LEDs, on a perforated board, five binding posts and one on/off switch.