Variable Tension, current limited, 10Amp Power Supply Unit

**Christophe Mineau** · Jan 26, 2020, 01:11 PM

Hi Folks,

I'm on my way to prepare a homemade Metal plating setup, and for that I needed a power supply unit with good control on it.
Here it is, it's a nice extension to the previous one I already showed :
Benchtop Power supply
Which was basically a re-spin of an old powerful ATX PC power supply, delivering 12V, 5V , 3.3 V and -12V

Here, for plating application, I need more flexibility, so I made an extension to the ATX PSU, using a kind of magical board I discovered, which is based on the LTC3780 chip.
This boad can take any DC tension as input, and can deliver , whatever the input level is, a 1V to 30V, up to 10Amp.
So it's both a step up and step down regulator. All this is based on a digital circuit, and is quite sophisticated.
You can find the boad on the usual online market places, I purchased mine for 20€
Look for
"LTC3780 DC 12V Voltage Regulator Input 5-32V Output 1-30V Automatic Step Up Down Regulator Charging Module 10A"

So, I basically replaced the onboad micro potentiometers by faceplate "macros" ones, added a nice little voltmeter and ammeter.
First pot is for controlling output tension, second pot is for controlling current limitation.
If you set the current limit under the level that requires your load, the board lowers the tension so that the current is what was set the limitation to.
There is an other pot on board that sets an input under tension level, under which the boards stop working.

I added a PC fan, just in case ...

I put everything in a nice homemade wooden enclosure (no , it is not 3D printed, that's not the idea).
It is powered by my ATX PSU, it can be 5V or 12V no difference.

And here it is :

**DIYer** · Jan 26, 2020, 02:08 PM

Thanks Christophe Mineau! We've added your Variable DC Voltage Regulator to our Power Supplies category,
as well as to your builder page: Christophe Mineau's Homemade Tools. Your receipt:

Variable DC Voltage Regulator by Christophe Mineau

tags: power supply, adjustable

**H0$$** · Jan 28, 2020, 07:37 PM

Thanks Don’t be discouraged, please post more

**FEM2008** · Jan 28, 2020, 09:56 PM

Originally Posted by Christophe Mineau

Hi Folks,
I am personally less and less prone to post the things I make (am I the only one with this feeling ?),......

(This may very well be my last one here)

I hope this is not your last, and thank you for this useful post. I am an electrical and mechanical engineer, and I found your post very helpful. I'll share this with my colleagues, as we are always short on test supplies in the lab but have lots of old PC supplies.

Kind regards

**tonyfoale** · Jan 29, 2020, 02:10 PM

Christophe,

Thanks for the tip on the LTC3780 chip, I shall follow up on that. I for one enjoy your well finished projects, but it is your choice whether you want to contribute in future. Do what you feel is best for you. I ask myself the same question whenever I make a post.
Good luck with whatever decision you come to.

**DIYSwede** · Jan 29, 2020, 03:19 PM

Thanks for the tip, Christophe - all the best!

LTC3780 Data sheet for the curious of you out there, thinking "-This seems too good to be true?"

https://www.analog.com/media/en/tech...ts/LTC3780.pdf

-Anyone still believing this chip can crank out and deliver 24 V @ 10 A out of a single AA battery?

No free lunches today, either - Sorry! But still a darned interesting chip and a clever application of it!
I've got a few 12 VDC 750W server PSUs lying around that without sweat could feed this chip to the very top.

Thanks
Johan

**jdurand** · Jan 29, 2020, 05:24 PM

Since the chip requires at least 4 V to operate...not likely.

One thing to remember is these are all Watts to Watts converters with a loss due to efficiency. I typically figure a worst case of 80% efficiency.

So, input current x input voltage x 0.8 = output current x output volts

**Christophe Mineau** · Jan 29, 2020, 06:17 PM

Thanks guys, for the encouragement and the good comments. Sometimes, I m really fed up with the social networks, and regret the golden Era of the Forums...
Yes, that's true, it's watts for watts with the cost of inefficiency, but this little thing is rated 130 w, and the digital chip seems very clever to provide the best and minimize waste.
The fan does not seem mandatory and the fact it doesn't heat too much makes me think it's quite efficient.
It really is a good extension to an atx psu, which has actually far too much watts than necessary.
I like it. Yesterday, I made my electrolytes with it, it sustained 10v 3A during 3hours and half, not even hot, so that's not a gadget.
,

**tonyfoale** · Jan 30, 2020, 03:58 AM

Originally Posted by Christophe Mineau

The fan does not seem mandatory and the fact it doesn't heat too much makes me think it's quite efficient.
It really is a good extension to an atx psu, which has actually far too much watts than necessary.
I like it. Yesterday, I made my electrolytes with it, it sustained 10v 3A during 3hours and half, not even hot,.
,

You are outputting 30 watts there, so at 80% efficiency you will only be heating your box with 7.5 watts. Fan not needed.
However, if you run it at the full 130 watts (assuming that is output power) then the waste heat will be 32.5 watts, you may need the fan for that.