CC/CV Regulated Bench supply
I needed a bench supply with CC/CV mode so I looked for online designs. All I can find were LM723 based and have fixed current limit set. I needed adjustable so I kept on looking.
And then browsing my library of PDF datasheets, I stumbled upon an application circuit from the LM317 datasheet.
Some parts were already hard to find and I didn't have a 250K 10 turn pot in my parts bin so the values were adjusted according to parts availability.
I doubt the transformer I used could handle 5A so max output current was lowered to 2.5A.
I also wanted separate LED's for CC and CV mode and a clever little circuit with an optoisolator and a transistor was used to make it work.
Here's the power supply.
Fan sucks air through the heatsink fins through the area under the blue 10 turn pot and blows hot air out through a hole in the back.
Panel meters are digital and requires an isolated 9V supply. I made a capacitor based isolator but has trouble displaying voltages when there is noise on the AC line. I'll have to redo that and I'll take more pics of the internals when I get to messing with it.
Here's another with labels and while testing a car amp...
An output switch is necessary for when adjusting the output voltage before connecting the load. Also, during shutdown, the output fluctuates and sometimes overshoots. The switch allows me to be able to connect sensitive loads only when the supply has stabilized.
Page created and copyright R.Quan © 06 Feb 2011.