Rev. B PCBs have arrived

A project log for ElbSupply - Simple linear bench supply

This project aims at building a rather simple yet useful bench power supply for everyday tinkering.

EliaElia 05/30/2015 at 14:540 Comments

Sorry for the long inactivity but I'm still very busy and the shipping of the PCBs took very long this time. After another 4 weeks of waiting I could finally pick up the PCBs from the post office yesterday evening.

I immediately started assembling and debugging the circuit. As of now the constant voltage part of the supply seems to be working fine after adjusting the software for the new output voltage range and fixing a mistake in the voltage adjustment circuitry.

The constant current adjustment needs some more fiddling with, I think the time constant of the LPF is too long for effective current limiting.

As you can see the new LM350 also has a small heat sink attached to aid in cooling the device. The LCD now has an LED back light driven by a constant current circuit.

The two TO-93 packages you see are 2N3904s that I bodged in instead of the SOT-23 2N2222A which I seem to have misplaced (they definitely show up on my distributor's invoice and I swear I had them somewhere 3 weeks ago :P).

I just wish I had shown my schematic to others before doing the layout and ordering new PCBs, maybe the would have caught a wrong feedback resistor in the voltage adjustment circuit.

So as you can see the project is still active it's just finding the time to keep it going is a bit hard currently.