Build Your Own Variable Lab Bench Power Supply

In this project I will show you how I combined a LTC3780, which is a powerful 130W Step Up/Step Down converter, with a 12V 5A power supply to create an adjustable lab bench power supply (0.8V-29.4V || 0.3A-6A). The performance is quite good in comparison with other models which cost around the same. Let's get started !

Step 1: Watch the Video !

The video gives you all the information you need to build this correctly. But I will also present you a parts list and more pictures for convenience.

Step 2: Order Your Parts !

Here is the parts list with example sellers (affiliate links):

Ebay:

1x LTC 3780: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 12V 5A Power Supply: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x AC Input: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x AC Switch: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x Voltage/Current Display: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x Binding post: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 200kΩ Potentiometer: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

1x 500kΩ Potentiometer: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

2x Knobs: http://rover.ebay.com/rover/1/711-53200-19255-0/1?...

Aliexpress:

1x LTC 3780: https://s.click.aliexpress.com/e/_dUULcjH

1x 12V 5A Power Supply: https://s.click.aliexpress.com/e/_d6OKO63

1x AC Input: https://s.click.aliexpress.com/e/_d6rs11H

1x AC Switch: https://s.click.aliexpress.com/e/_d8ahMCn

1x Voltage/Current Display: https://s.click.aliexpress.com/e/_dTLhigJ

2x Binding post: https://s.click.aliexpress.com/e/_dTyymFV

1x 200kΩ Potentiometer: https://s.click.aliexpress.com/e/_d6mRdPZ

1x 500kΩ Potentiometer: https://s.click.aliexpress.com/e/_d6mRdPZ

Amazon.de:

1x LTC 3780: -

1x 12V 5A Power Supply: http://amzn.to/1FIc4vK

1x AC Input: http://amzn.to/1FIc7b5

1x AC Switch: http://amzn.to/1FIceDs

1x Voltage/Current Display: http://amzn.to/1AwUnt8

2x Binding post: http://amzn.to/1ENKLzo

1x 200kΩ Potentiometer: http://amzn.to/1ENKQmP

1x 500kΩ Potentiometer: http://amzn.to/1AwUEfD

2x Knobs: http://amzn.to/1FIcuCC

Amazon.co.uk:

1x LTC 3780: -

1x 12V 5A Power Supply: http://amzn.to/1FId7fh

1x AC Input: http://amzn.to/1R1lRl9

1x AC Switch: http://amzn.to/1AwWsoT

1x Voltage/Current Display: http://amzn.to/1AwWFsa

2x Binding post: http://amzn.to/1ENM3uh

1x 200kΩ Potentiometer: http://amzn.to/1FIdAyb

1x 500kΩ Potentiometer: http://amzn.to/1FIdBSx

2x Knobs: http://amzn.to/1AwXvoY

Step 3: Build It !

Here are some picture which should hopefully help you to build your own supply. And be careful when working with mains voltage !

Step 4: Success !

You did it! Now you have successfully built your own variable lab bench power supply!

Feel free to check out my Youtube channel for more awesome projects:

http://www.youtube.com/user/greatscottlab

You can also follow me on Facebook, Twitter and Google+ for news about upcoming projects and behind the scenes information:

https://twitter.com/GreatScottLab

https://www.facebook.com/greatscottlab

Comments

[mscirocco]

This looks great. I'm getting ready to build a CC CV adjustable power supply and comparing DIY projects, yours looks really good. I thought I'd ask if you have a more recent iteration. Thank you.

[ramrout406]

Good

[JJSLAYER]

What should I do for the box? Can I 3d print it or should I build it with wood or metal?

[DennisB36]

I've attempted to build your Variable Bench Power Supply a couple of times, and after watching your youtube presentation and reading your post, I have not been able to get it working as you show, Couple of problems I ran into was while testing the LTC3780. I kept getting a red fault light and no green led. I finally (on my 3rd board) found some informatio on the internet that you need to turn the Volt and Amp adjust pots about 20 times counter- clockwise that cured that, Now the big problem, How did you get the two pots (a 200k and a 500k) that you suggest to work in your circuit? There just doesn't seem to be the adjustment range to make the darn think to work. Which brought me back to the red fault led again. Went back and re-installed the original two pots and every thing works that way. Not very practical for use as a variable bench power supply. Any suggestions?

[OsamaZ7]

Can you please share the circuit diagram

[william.h.mic]

I did my best to remake it from the pictures.
https://gyazo.com/28196673603cbac7ca0b90d0f4c5b436

[SteveSi]

The diagram is wrong. You should not connect the thin black wire going into the meter. Inside the meter, the thin black wire connects to one side of the internal shunt. This causes the 0V of the input to be connected to the 0V of the output. This puts the internal shunt of the current meter in parallel with the internal current shunt\sensor in the DC-DC board. It means the current reading on the meter is wrong and also you cannot adjust the current cut-off pot.
See the instructions for the meter. You ONLY connect the thin black wire if you are powering from an independent power supply which has an *isolated ground* like a battery (not a common ground). https://www.banggood.com/custlink/GGmGegbp95

[dush71816]

I think the diagram is for non shunted power meter, there are 2 versions available, 1 is shunted and can meqsure 10A max and others are beyond that ampere range and do not have shunt. To provide load to such meter the black wire should be connected. Correct me if I am wrong.

[dush71816]

Should have included wiring diagram. I am having confusion about connecting 3 thin wires from power meter. My meter is non shunted one as per supplier and range is 0 to 100 amp. I think the shunt is for a dummy load and bears 10A max. But how 3 wires should be connected with posts is confusing.

[TurkelA]

Hi Scott, I am big Fan of your youtube channel and instructions :)
I would like a bit modify current setup to use with my "3A 12V toroidal transformer" and "LM317 Adjustable Regulated Rectifier Filter". then connect LM317 directoly to LTC3780.
Will this setup work OK? The purpose is to build Liniar Power Supply rather than switching one.

Grate Thanks,
Turkel.

[nickr20215]

yes as long as it's not over 12v

[MathieuC35]

Hello. I'm a little confused. My display does not look exactly like the one in the pictures. The power wires are thin and the group of 3 wires are thicker. That group has black, red and green but no yellow. It doesn't look like they are identified on the board either. See picture. Can I make it work or should I just order a new one that looks like the one in the pictures ?

Thanks !

[nickr20215]

Check the datasheet of your vesion it should have a wiring scheme

[InstructaPudah]

Would it be possible to control the LTC3780 digitally, maybe with an Arduino and a DAC or digital potentiometer(s) with rotary encoder for voltage control instead of the pot?

[Tricep Terry]

i'm also investigating this, for now going for a kinda weird solution which is to mount the potentiometer near a servo motor and use gears to turn it, its gonna be ugly for sure, yet practical and simple.

[Zemon_Compute]

So with mine, I can adjust the Voltage fine but the current I cannot adjust at all. it only automatically draws Current. anyone know what could have caused that?

[Swami7233]

Did you able to adjust current after removing the small black wire?

[SteveSi]

The meter is wired up wrong. Do NOT connect the thin black wire going into the meter.

[Zemon_Compute]

So i should disconnect this one from everything?

[SteveSi]

Yes