A good lab power supply can cost a lot, even a basic one is not all that cheep and what you get is not all that convenient. 1 variable supply and that’s about it. But with off the shelf components and some time you can make a good lab supply for about $100.
When I am experimenting, i will often build circuits on separate boards and wired them together into a functioning whole, and this means needing 3 or more power supply rails. Most of the things i build do not have huge current demands, so as long as each rail can supply 2A it will do all that I need and supply voltages from 3 to 30v. So, with that as my design criteria, the basic specs for the lab supply became as follows.
- 4 channels
- 10A maximum current
- 2 variable supplies 3-12v and 12-30v
- 2 fixed supplies
I am not a fan of building things that can kill me, so for the power supply I used this 10amp 12v switch mode PSU and for the variable supplies I used a Buck and Boost converter to get the 3->30v coverage. Actually it will work down to 2.5v and up to 34.5v, a nice huge swing.
Next was to mark out, drill, cut and mount the voltage display modules, the pots and binding posts. The 3-12v supply has a 10 turn pot and the 12 to 30v a single turn pot.
The integrated power jack and switch was then installed on the rear panel.
10amp house wire was used to wire the switch and 240v power, I soldered and heat shrinked this side.
Spade connectors were used to wire into the psu.
The buck and boost converters were mounted onto the top of the psu.
The rest of the 12v wiring was then installed, crimps being used on the psu side and everything else soldered.
Wiring complete, liberal use of zip ties to make it tidy inside.
The inside of the front panel now it is all wired up.
And now with 240v applied. Works a treat, the voltages are stable under load and for under $100 I have a pretty good lab power supply that will keep up with my home brewing needs.