Friday, July 25, 2014

Constant Current, or Constant Voltage?

I needed a Constant Current power supply for my bench. Now I don't know if you have priced bench power supplies lately, but they can be several hundred dollars. Not any more! Would you believe a 40v 3a adjustable voltage or current supply for about $20?
http://goo.gl/WYD7m3
I grabbed a used 24vac HVAC transformer, soldered a bridge rectifier on top, and fed the input on this board. I put a 300ma 1w LED on the output, and I'm controlling the brightness by controlling the current, even down to 2ma (dim), all the way up to 300ma (blindingly bright). I could go higher, up to 3000ma, but that will let the magic smoke out.