A few years ago I saved a large Astron 13.8v 50A linear power supply from a electronics recycling bin.(dumpster dive style). When I got it, its control circuity was removed so it was basicly a large heatsink with some BJT's on it, filter cap, diodes and the transformer. So I put together the best circuit that my 14 yr old self could. While today I know that it is horrendous it did serve me well through melting much nichrome wire and powering car audio equipment. Looking at it now, it has no protection ciruits, voltage sags under load, and spikes on load disconect. So its time to improve on it.
My thought was to turn it into a variable power supply with both CC and CV. Taking inspiration from Dave's and others videos and my better electronics knowledge I think I could pull it off if I took the time. While only in brainstorming stage my current issue is how to do the current measurement? If I do a simple resistor, and I say go for a .5V drop, thats 25 watts dissipating across it at full current. To me that seems both a waste and my resistor would change value quite a bit due to increased temperature. Or do I use a premade shunt resistor but that would give me something in the 100-50mv range at full load right? Would that be too low to get accurate readings at low current? I am not looking for anything super accurate or close to it, but even +-100ma would be ok. I am more concerned about keeping voltage to a higher tolerance.
Thanks for any help and for putting up with my first post!