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Show your favorite and most used benchtop PSU

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linux-works:






all from ebay except the one with the price sticker on it, that was from a local store (Halted).

Rigby:
I love the voltage dials on those Power Designs supplies.

KarlosVandango:
Hello Fellas,

Hopefully you'll find this interesting... I constructed this a few years ago... (I think I was 13). After driving my parents to despair over battery usage, my Dad (who's friend was a blinding instrument guy (and they both worked at the local nuclear power station)) helped me design a twin PSU. I built the circuit, he went through with me how to start, research the components etc... (before .pdf datasheets and internet! Had to use RS components and Maplin catalog) and Dad did the drilling and "sourcing" of all the bits etc.. ;)

Max voltage output is 25V per channel, 2A per channel can be drawn (or if you bridge the outputs you can get a whopping 4A supply) ;)

Biased on the LM723, this unit has also short-circuit protection, AND you can limit the current going out. Although the gauges are analogue, they still do the job, and I didn't want to mess up the calibration of the dials. ;)

I'm 35 now, and the unit is still in use. Unfortunately, the PSU used to have a nasty habit of discharging max voltage through the output terminals when you turned the unit off (no bleed resistors on the caps!!). When I was an apprentice, I fitted bleed resistors AND relays to disconnect the output terminals (along with additional snubbers etc).

God only knows now where I put the schematic for it... But I'm sure it wouldn't be too difficult to reverse engineer... Hmmmm....

Regards,

Karl











KarlosVandango:
Forgot this one....



You can see the other bits added over the years... Do I upgrade to digital displays...? I think I'd rather build another one, this unit works, although you do need a multi-meter to get really accurate settings. But the gauges are spot on, it's only when you require "point" of a volt... :)

nctnico:
Overshoot at power down is a nasty habit of many self build and cheap power supplies. It can kill circuits if you are unlucky. I recall a case when an intern tested tens of boards with a cheap PSU. Ofcourse all the boards where OK and they got shipped to the customer. At the customer none worked. After some questioning it turned out he used the crappiest PSU in the 'lab' which had this overshoot problem which killed all the 4000 series logic. Some people objected when I dumped the PSU in the bin. Another lesson to be learned is that you should put regulators on a board to make sure the supply voltage is within range.

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