Author Topic: Idea for video designing a simple power supply that runs off mains  (Read 995 times)

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Offline Beamin

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I watched your videos on power supplies *watched almost all your videos while I was bed ridden for two years! Remember book reviews and when you didnt have as much enthusiasm in your voice?) My 1st power supply I built was your lm 317 model but it was lacking in features.

I was thinking how to make a simple lab power supply that uses three basic parts:
!. 120/240 to 24 or 48 vac step down linear transformer
2. To display current and voltage use those volt meters they sell off allibaba and other sites where you have a XX.X volt meter thats all self contained in a 3 seven seg. display package thats all contained with two wires coming out is 1cm X 3 Cm and costs a buck or two.

Doesnt have to go to 0 volts but if thats easy to do it would be a plus.

That way you could have a professional CC CV power supply that doesnt use an arduino so no code and has 0.1v/A accuracy displays. Im guessing you could build some sort of voltage divider circuit  that would convert the amps output to volts to run the CC display.

Would be a really cool project and save the 100 bucks + that a commercial one costs; my velman CC/CV 35v 5a handheld power supply costs me over 200 bucks but its great except the limited 35 volts.

This way you plug it into the wall have a power switch two pots for adjustment and your output. A bonus would be adding a circuit that trips when you go over your CC, that I have no idea how to build electronically.
 
I would like to see it built with LM317 or lt380 to keep it simple and analog
« Last Edit: November 14, 2020, 08:03:05 pm by Beamin »
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Offline Buriedcode

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Re: Idea for video designing a simple power supply that runs off mains
« Reply #1 on: November 18, 2020, 08:03:07 pm »
The internet is full of schematics for such relatively simple linear supplies.  The costs would be the mains transformer, DC smoothing caps and then your current/voltage monitor.
You didn't mention current capability, which determines the size/cost of the transformer.  Also, housing should be carefully done to ensure you're grounding exposed metal (but you could leave the supply floating).  All of this is cost and hassle that makes the cost of a simple power supply quite reasonable.  With that said, I'm sure we've all made DIY PSU's, and its a good exercise.

This bit:
A bonus would be adding a circuit that trips when you go over your CC, that I have no idea how to build electronically.

CC is constant current, that is, the output is regulated based on current flow, so the voltage is limited only by its maximum output (so the load determines the voltage).  You can't go "over" your CC current, since that is regulated.  Are you talking about current limiting, as in, fold back?  This isn't the same.


I would like to see it built with LM317 or lt380 to keep it simple and analog

Again, because both devices are quite old, there are many many web pages detailing projects using them. You can find one, prototype and test with a separate power supply first (like a DC brick).  It sounds like you have a pretty decent power supply, with 35V @ 5A with CC/CV.  What features does it lack that you require?
 


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