Sunday, April 6, 2014

Bench Variable Power Supply

I have been wishing for a bench power supply for quite some time. Part of the problem is you need one to be able to make one. So I decided to cheat and make one the easy way. It is also the proper size for my limited work area.

I still intend to make a proper one with current limiting and a few more amps, but this will  help in  the mean time.
Variable 1.5 to 30V 3 amp supply, No current limiting. Driving a drill spindle.

The local electronics parts house stocks a few of the popular Chinese modules. So I bought a box and some modules:

The layout. Amp meter requires separate supply.

The modules from top to bottom:
Digital DC Voltmeter 2.5-30V red
DC AMP METER DC 0-10A 2.5-30V
DPDT switch for input and battery on/off
LM317 based variable supply 
  Voltage Regulator AC/DC 1.25-37V max 2.2A
  overload and short protected
Banana plugs and 9v battery
not shown 19V DC old laptop supply

Links to similar:

While looking for the sample link for the mini drill I saw many like I wish I had found! This one will drill holes in PCB but the runout is to big for milling and the collet is real trash. A 0.8mm drill bit fits with considerable force.