4 Channel Variable Lab Power Supply.

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

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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.

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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.

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The integrated power jack and switch was then installed on the rear panel.

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10amp house wire was used to wire the switch and 240v power, I soldered and heat shrinked this side.

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Spade connectors were used to wire into the psu.

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The buck and boost converters were mounted onto the top of the psu.

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The rest of the 12v wiring was then installed, crimps being used on the psu side and everything else soldered.

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Wiring complete, liberal use of zip ties to make it tidy inside.

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The inside of the front panel now it is all wired up.

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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.

 

 

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