A while ago, I built my own 30 Amp power supply after seeing how much they cost these days. It has performed flawlessly since, so I thought it was time for a make-over. The heart of the unit is an 'off the shelf' 30 Amp switch mode power supply module, cheap as chips from Amazon. At first I ordered a couple of cheap Amp and Volt meters for indication. Problem was that after a while they started to stick, especially in the hot weather, and I also couldn't get a definite reading from them. Originally, the DC terminal posts were at the front where you would normally expect to see them. I wanted them at the back out of the way for neatness, so I re-routed those. I re-hashed the box to accomodate a 20x4 LCD display and programmed a micro controller to do the work. A DS18B20 temperature sensor was also installed close to the electronics. I used an ACS712 - 30A as the current sensor. This sensor has received quite a lot of bad reviews, but I don't seem to have a problem with it. The main concerns are that the terminal connections are incapable of carrying the 30 Amps that it's rated at. Some say that it got extremely hot when passing only 5 Amps. Well I must concurr that the connections do seem a little 'puny' but I managed to get a significant sized conductor into the terminal block after prising it open a bit with a small screwdriver. I have been testing this unit for a few days now and with an intermittent current of about 10 Amps, I haven't witnessed any overheating issues. The temperature sensor will alert me to this. After a bit of messing with the calibration routines for the voltage and current, it was looking good. A couple of days of testing and tweaking, and a coat of matt black paint, now it takes pride of place in my shack. Very pleased with it!
(Update - After experiencing an accidental short circuit on the PSU, I have decided that I need to have some physical protection on the output, like a fuse. The unit itself has short circuit protection but I don't trust it. My monitor registered a maximum current of 35.8 Amps, if even only very briefly. This could be dangerous and a fire hazard. I intend to install a fuse to be sure, ASAP).
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