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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:

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?...

Amazon.com:

1x LTC 3780: http://amzn.to/1DMl7G4

1x 12V 5A Power Supply: http://amzn.to/1DMlfp5

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

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

1x Voltage/Current Display: http://amzn.to/1c9uGK1

2x Binding post: http://amzn.to/1GRcw9X

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

1x 500kΩ Potentiometer: http://amzn.to/1E6t89w

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

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

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GreatScott!, I have a doubt and I can't find an answer. :/<br><br>The thing is... The voltage/current display shows what the load draws, right? So, if you power it up without connecting it to anything, it would show the voltage and zero amps.<br><br>So... How to limit the current that way? Do you use something as load to do that? If so, what do you use?<br><br>Thanks a lot!
<p>Just built mine from an old cheap ATX power supply. I'm using the 5V rails to power this regulator instead of the 12V as I noticed the output voltage was more stable this way (not sure if it's because of the LTC3780 or because of the cheap psu). </p><p>The only annoying thing is that those cheapo eBay amp/meter units are horribly inaccurate even after adjustment. The volt reading is inaccurate by about +/- 0.5V at the lower and upper ranges. The current reading is even worse...it's literally off by several factors and the potentiometer adjustment does not make much of a difference. Anyone else have this problem, or did I maybe just get a bad meter?</p>
<p>Will this --&gt; <a href="http://www.ebay.com/itm/DC-5V-32V-to-1V-30V-10A-LTC3780-Automatic-Step-Up-Down-Regulator-Charging-Module-/201473173964?hash=item2ee8bca9cc:g:DQwAAOSwU-pXunel" rel="nofollow">http://www.ebay.com/itm/DC-5V-32V-to-1V-30V-10A-LT...</a></p><p>work, it doesn't have a heat-sink underneath but there seem to be heat-sinks on top. Will there be any problems?</p>
<p>I have all the parts except the resistors.</p><p>The resistances used in the video are necessary in the final circuit?</p>
ordered everything just can't wait to try it out. how can I change the pots to the ones I ordered without damaging the circuit as some people have above and ended up breaking the tracks on the board and having to buy a new one . also if use a plastic ABS project box do I need to figure a way to earth the ac input to the box or will it be fine with it being plastic Ie. non-conductive please Some help.<br>cheers Daniel
<p>yes, u can use plastic case or acrylic sheet to make the profile for power supply. I'm using the acrylic sheet to make one. </p>
I'm building this with a twist. I'm using the computer power supply as the supply for the whole thing also using the power ports from the computer for static 12v, 5v, &amp; 3.3v with a variable output for the other part. the case I've used is a bit too small, but I'm making it work.
<p>I was thinking of making the same tweak!!!!</p>
ordered everything just can't wait to try it out. how can I change the pots to the ones I ordered without damaging the circuit as some people have above please Some help cheers
<p>Ok so I tried a different technique which should be safer if you're worried about unsoldering the pot. The board seems very sensitive to heat so...</p><p>Take some standard headers like so <a href="http://www.ebay.co.uk/itm/40Pin-2-54mm-Male-PCB-Single-Row-Straight-Header-Strip-Connector-for-Arduino-TK-/331468762715?hash=item4d2d13ee5b:g:~2UAAOSwk5FU0N70" rel="nofollow">http://www.ebay.co.uk/itm/40Pin-2-54mm-Male-PCB-Si...</a> male or female does not matter. These pin headers have the same pin pitch as the pot and can be easily and quickly soldered to the bottom of the board. Just tack them to the pads that are already there. This is much easier than unsoldering the pot. Now take a sharp knife and cut the legs of the pot that's on the board (carefully) take your time try not to stress it.</p><p>You now have one pot removed and one header in place waiting for the new pot, just solder the wires to your new pot then plug them into the header, solder on a header connector.</p><p>The header pins are not 100% necessary but i find them convenient. You can then swap out the pot later on for say a multi turn pot or a pot and stepped resistor ladder, or whatever else you come up with and you won't have to solder to the board again. </p><p>Thanks scott for the instructable I hope you don't mind me offering a suggestion</p>
<p>Good thinking batman, i just ordered some as i must have messed around with the board some how when unsoldering the original pots!!</p>
<p>For the pots, It looks like pin 2 goes to the center pad on the board where the old pots were. Does it matter which pads pins 1 &amp; 3 go to on the board?</p>
<p>It doesn't matter, it determines which way you have to rotate (clockwise/counter clockwise) to increase your voltage/current.</p><p>You can swap them to change the direction.</p>
<p>how can i prevent backflow?</p>
<p>You can use diodes to prevent reverse current into the power supply.</p><p>Though the power supply should be reverse current protected.</p>
<p>A quick newbie question</p><p>- can i just directly power the LTC 3780 ?</p>
with what do you want to power it?
<p>12v 5a dc power supply</p>
<p>with a laptop power brick</p>
yeah that would work
<p>Hello guys, can someone tell me if linear/algorithmic pots matters ? Also could a 250k pot rather than 200k work fine?</p>
<p>I'm also interested in this question! Till yet i didn't find a 200k pot in my preferred shop :-( only 250k pots ...</p>
<p>i'm also interested in that question i can't find any on lightinthebox/ bangood</p>
<p>LCT 3780 :-)</p>
<p>You have to be careful, some sellers send the version without the aluminium backplate although the pictures are with the aluminium heatsink.</p>
I made my own but managed to fry the ltc i dont know how... I am now waiting for a replacement.
maybe it shorted with the 12v power supply's casing
<p>I insulated it (not visible in this pic). </p>
<p>How would I wire a 3 pin toggle switch instead of the 4 pin one he used? Thanks in advance!</p>
<p>Will this power supply be good for this?<br>It is 12V and 7.2A<br>This is from a old ps2(fat version)</p>
<p>It should work, but be careful!</p>
Works like a charm... ✌
<p>It would be better if you could include a wiring come hook-up diagram as the images in the photos lack clarity. I am especially keen to see how that Chinese meter is connected as the info on its eBay listing are in Chinese and very obscure. Can you please advise.</p>
<p>Is it possible to use an old laptop power supply (with Output: 20V DC / 3.25A) instead of the 12V 5A Power Supply, or would that not be stable enough as power supply for the LTC3780?</p>
<p>One of the parts are obsolete now, no ones selling them anymore. :(</p>
<p>Pot question ... you list one logarithmic and one linear in the parts above. Is it important to use them as listed, one of each? Or can they both be logarithmic or linear?</p>
<p>Hi all !</p><p>Most likely it's a stupid question... but.</p><p>Why do you need a current adjustment ?</p><p>I mean, the thing you power up should draw as much as it need, no ?</p><p>Thanks for you'r answers !</p>
<p>In my case, I will use this to locate a short to ground on laptop mainboards. Set the voltage to the rail requirement, and slowly bring up current. The will make a component that is shorting to ground heat up, making it identifiable. Or in some cases, the bad component will blow. In the event it's a short inside the board, at least there will be a hot spot. Unfortunately, the laptop power supply shuts itself off when there is a short to ground on the board. Making it difficult to locate the problem area. Using this bench supply, will hopefully come in handy.</p>
<p>Your building a prototype of somthing and don't want to burn up the components with to much current. In the event you made a mistake. </p>
<p>You need to adjust current when you charging batteries. If you will charge them with 5A batteries could heat up or explode. I hope i answered your question.</p>
<p>What if you wanted to simulate a circuit where 5Amps aren't available? e.g. a 9V battery or a button cell battery</p>
<p>Thank you so much for your inspiring Video :D </p><p>I even saw the case you used next to the one i used, at my local Conrad store ;)</p><p>But this one does it for me :)</p>
<p>Found this rough translation of the Datasheet (in Chinese): </p><p><a href="https://raw.githubusercontent.com/Marzogh/Benchtop-Powersupply/master/Datasheets/WD2002SJ%20-%20LTC3780%20buck%20boost%20converter.pdf" rel="nofollow">WD2002SJ - LTC3780 buck boost converter.pdf</a></p>
<p>I made it. I got two output... the left one is steady 12V and the second one goes through the LTC3780. But does anyone que tu same problem as me? When I turn the pot to get higher output voltage, when I reach around 11V, fault led flashing on the LTC3780... output voltage fall down when fault led is on... then the fault led turn off and my out voltage goes up... then the les turn on and...</p>
<p>You have to turn the Low Volt Cutout potentiometer screw (the one closer to <br>the in connection) counter clock wise till the fault led turns off<br> and the ok led turn on</p>
<p>I get that kind of behavior if the current limiter is set too low. Maybe it's something with that?</p>
<p>Really fun and useful build. Works great! One addition I made was adding an output switch in addition to the main power switch. I like being able to turn the unit on, hook up my leads, dial in the voltage and then switch on and off power to my circuit. </p>
Hello,just wondering is possible to use power supply like this one to charge car's lead acid battery?
<p>This is very funny. Where is the connection diagram? How can I convert the fixed 12v 5amp power supply into variable one?</p>
Hello, I want to ask if i can use a 12v 10 a power supply instead a 5amps with a ltc 3780 and a lcd led display 0-100 v 10 ?

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