## Introduction: DIY Variable Power Supply With Adjustable Voltage and Current

Hey Guyz, This time I'm making a variable bench power supply.This is the most useful equipment for a hobbyist and DIY maker cause while making or testing circuits, it needs different values of voltage and current. That's why every DIY maker must have their own bench power supply. Now I'm going to show you how to build an awesome variable bench power supply. So take your tools and let's get started :)

If you like this project then please do vote for me :)

I'm using here LTC3780 DC adjustable buck and boost converter. which is an amazing module. It can deliver DC (1-30V) and up to 10A current depends on your input power source, in my case I'm using DC 12V 3A input power source. I easily get continuously adjustable output voltage (1-30V) and current (0-6A), which is pretty enough for circuit testing and other things.I'm also using 7805 voltage regulator IC for 5V constant voltage and current.

This Power Supply Has Following Features:

• Input Voltage 12V DC.
• Input Current 3A.
• Output Voltage (1-30V) Continuously Adjustable.
• Output Current (300mA-6A) Continuously Adjustable.
• Output ripple 50mV.
• Constant Voltage And Constant Current.
• Short Circuit Projection.

Here's The Complete Tutorial And Demonstration Video.

## Step 1: The Parts List

We need these following parts to build the power supply. I bought some from online and some from the local store.

Parts List:

• Digital Voltmeter Ammeter Display
• 500k & 200k Linear Potentiometer
• 12V DC Fan
• 7805 IC For 5V
• 100uF & 10uF Capacitor
• 1N4001/1N4007 Rectifier Diode
• Banana Socket 4ps
• Knob 2ps
• DC Switch
• 2.1mm DC Jack Connect
• Wires
• HeatSink
• Wooden Blocks
• PCB Board
• 4mm Acrylic Sheet

Tools List:

• Glue Gun
• SuperGlue
• Sandpaper
• Mini Handsaw
• Soldering Iron
• Drill Machine
• Rotary Tool
• Spray paint

## Step 2: Cutting the Acrylic Sheet

I'm using here acrylic sheet to making the enclosure of my power supply. This is an amazing material cause it is easy to cut, bend and sand. it's also so affordable. You can use the acrylic sheet to make your own power supply. So let's get started.

• First, take a measurement of acrylic sheet.
• Cut the acrylic sheets according to the marking.
• Place the voltmeter display and mark it.
• Next cut the marked section with a rotary tool and metal file.
• Again mark the areas for air passing
• Cut the marked area using a mini hacksaw.
• Take the measurements of dc socket, dc switch and dc fan, then mark it.
• Drill the holes and smooth the edges with a metal file.

## Step 3: Sanding the Pieces

First, remove the paper cover of the acrylic sheets. Then sand the acrylic sheets until getting a smooth flat surface.

## Step 4: Attaching the Pieces

We'll start off by applying super glue on the edges of upper and lower panels. Next, attach the side panels to each panel.

## Step 5: Painting the Pieces

I decided to paint the upper and lower encloser of my power supply. I choose matt black colour for my power supply.

## Step 6: Attach Extra Pieces

We need some extra pieces for mounting screw. Now take four same size pieces and attach these pieces using super glue.

## Step 7: Attaching Front and Back Panel

First, apply a great amount of superglue on the edges of the front panel. next, quickly position it to the lower encloser, then hold it for a couple of minutes. Use this same method to attach the back panel.

## Step 8: Mounting Components

In this Step, we'll mount every component. First, we'll start off by mounting dc switch. Then we'll use the screw to mount the dc fan. Then we'll mount other components respectively.

## Step 9: Mounting the Heat Sink

It's necessary to reduce the temperature of the power supply. So we need a heatsink and a cooling fan. Though LTC3780 dc converter has an inbuilt heatsink and this converter doesn't heat up. You can skip the additional heatsink. I'm here additional heatsink for better efficiency.

• First drill holes on the wooden block
• Use the screw to attach the heatsink to the wooden block.
• Now apply hot glue on the wooden block.
• Attach the wooden block to the enclosure.

## Step 10: Removing the Inbuilt Potentiometer

In this step, we're going to replace the inbuilt potentiometer of LTC3780 with the linear potentiometer.

• First, remove the inbuilt 500k and 200k trimmer potentiometer using soldering iron.
• Now solder wires to solder joint of the trimmer potentiometer.
• Solder those wires to new 500k and 200k linear potentiometer.

Note: When removing the trimmer potentiometer make sure that you don't heat the board too much. it could damage the dc converter.

## Step 11: Making the 5V Converter

I'm using here 7805 IC for addition 5v constant output. First, solder the components then Add a heat sink to reduce the heat.

## Step 12: Wiring Diagram

This is the complete circuit diagram of this power supply. You've to connect every component according to this circuit diagram.

## Step 13: Final Wiring

In this step, we'll solder every component according to the circuit diagram. After soldering every component, i tied all the wires with zip ties.

## Step 14: Final Asembly

Now Attach the upper enclosure with screws. Finally, we're done now. Plug the dc jack and the power supply ready provide (0-30)V and Up to 6A Output Current.

Thanks for watching this instructable. If you like this project then please do vote for me. I really need your vote and I know that you will do it.

RhexA (author)2017-09-07

possibly add a female usb port in the 5v output

imamfarid64 (author)2017-09-03

REUK.co.uk

thank you bro you done a great job,but i studied about lm317 voltage regulator and 2n3055 transistor. increasing transistor will increasing amps .you can see on site above, you will know that as many amps you need you will use so many amps transformer,there is no need for booster,but little up gradation is needed for variability of amps.diagram is bellow. thanks and regard.

Surajit Majumdar (author)2017-09-04

2017-09-04

I think the switching regulator he chose is a much better solution than an LM317 linear solution.

In addition to a plethora of other reasons, it won't get hot like the LM317 would.

2017-09-05

Yeah, you are right. This regulator won't get hot too much.

synapslap (author)2017-09-04

Unbelievable skills Mike. Superhuman skills Mike- you can do what machines cannot

Surajit Majumdar (author)2017-09-05

Thank you so much :)

Goran2203969 (author)2017-09-05

Great idea, nice performance. Inspire for challenge...Thanks

Surajit Majumdar (author)2017-09-05

Thank you so much sir :)

Nounou 2016 (author)2017-09-05

Good job !! Can you make links for Parts List

Surajit Majumdar (author)2017-09-05

Thanks. later I'll update the parts list ok :)

jtechian (author)2017-09-03

Pretty, but you still need a power supply to feed this! Why didn't you include a transformer and rectifier circuit in front to give the needed dc supply ?

wquoyle (author)2017-09-04

I think PSU projects like this are popular because a) everyone seems to have an old laptop PSU lying around (so total cost is pretty low) and b) not everyone wants to play with mains voltages. :) I think for 'hobbyists' (I'd include myself in that category) this an opportunity to build a worthwhile PSU with very little risk. I certainly wish LTC3780s etc had been around when I started out many years ago. :)

Surajit Majumdar (author)2017-09-04

Yeah wquoyle, I totally agree with you :)

wquoyle (author)2017-09-05

And I should have said that this is a very nice build, looks great. I'm about to build one myself and hadn't considered a fan could be necessary so thanks for that.

Surajit Majumdar (author)2017-09-05

Thanks, wquoyle. I hope you'll make a better power supply than this :)

Surajit Majumdar (author)2017-09-04

Thank you :) Actually, i wanted to make it small, that's why I didn't put any transformer and rectifier circuit.

warhawk8080 (author)2017-09-03

Very very cool...one suggestion for the output (just to make sure it's ultra clean)

Get 3 value capacitors 100uf, 1uf and 1pf in max rated volts of 40vdc or higher, solder them together (just wrap the leads around the biggest capacitor leads), then solder them across the output terminals...this provides a very wide frequency range smoothing capacitor, cuts down massively on the ripple caused by buck/boost converters and ensures pure flat dc
Like the deal on the right in this [image](https://oscarliang.com/ctt/uploads/2014/02/IMAG12411.jpg)...it looks silly..but works VERY well

I really like that build...very good!

May be a diode too at the input terminals to protect from reverse polarity.

warhawk8080 (author)2017-09-04

Diode would change voltage of output...it would be off .7vdc. does that variable voltage module protect from reverse polarity?

Surajit Majumdar (author)2017-09-04

I'm so glad that you like this project. Thank you so much for your advice. I'll sure try it :)

JohnW51 (author)2017-09-04

You might consider a switching regulator instead of the 7805 linear. There are several that will fit in the same footprint. Most do not need a heatsink, so the cost of the heatsink can be used to make of the difference between the 7805 cost and the switching regulator cost.

https://www.digikey.com/product-detail/en/recom-po...

Also, you mounted the circuit board (regulator board) directly to the heatsink. Aren't you worried the traces on the back of the board will short circuit on the heatsink?

throbscottle (author)2017-09-04

Nice project. But please edit the specification so it shows what it will actually do, rather than just the min/max for the module you used. It's worth noting that at lower output voltages than the input (buck mode), this type of supply can output more current than it's input current, and at higher voltages (boost mode) than the input there will be less current available as it will draw a lot more from it's power source.

50mV ripple isn't terribly good. An LC filter on the output like another commentator shows would be a big help. Use thick wire for the inductor though or you may get an unacceptable voltage drop.

Nice case, though I don't think super-glue is a very good choice of glue. It doesn't fill gaps and it's brittle (and you can't adjust the join!). I'd be more inclined to use a general purpose clear glue, or the hot melt glue you have.

Surajit Majumdar (author)2017-09-04

Thanks for your suggestion and later I'll update the specification :)

gismo1 (author)2017-09-04

I think this is a great instructable well laid out and easy to follow. Of coarse anyone who wishes to improve on what you have done in terms of noise can do so and then pass this back to you with an explanation of why they did so. wouldhelp you to

Surajit Majumdar (author)2017-09-04

Thanks gismo1 :)

PaulG97 (author)2017-09-03

I think that you did a great job with it. Looks as good if not better than something you would buy

Surajit Majumdar (author)2017-09-04

Thanks PaulG97,

misterxp (author)2017-09-04

Hello Surajit, when I saw the title I thought just another power controller". I am quite new to electronics and so can't comment on the accuracy of your circuit. However, I voted you because the instructable is clear and well done and I love you box. I think you made a big effort to make a good instructable and the end product looks very professional. Well done.

Surajit Majumdar (author)2017-09-04

Thank you so much misterxp. It means a lot to me :)

PaulG97 (author)2017-09-03

LOL if you like you could build me one.

DejayRezme (author)2017-09-03

Thank you very much! I need this to start learning electronics.

Is this a switching power supply?

DejayRezme (author)2017-09-03

PS: This is actually a very powerful for a lab power supply, right?

colinza (author)2017-09-03

Nope, a lab power supply would not be built like this. It produces too much noise.

Surajit Majumdar (author)2017-09-03

Actually, i used an old fan in my power supply, later I'll replace it with a good one.Then it won't produce too much noise :)

colinza (author)2017-09-03

I mean electromagnetic noise, not sound. Cheap buck regulators create RF interference on their outputs and inputs unless it's filtered out.

DejayRezme (author)2017-09-03

Oh are we talking about acustic noise or electronic noise / ripple?

DejayRezme (author)2017-09-03

Thanks. Well I'm not really working in a lab. How bad would the noise be for learning to use electronics?

colinza (author)2017-09-03

Totally fine for learning electronics.

Surajit Majumdar (author)2017-09-03

Hey guys, please don't compare it to a professional bench power supply. it's a handmade power supply.

jimmyf (author)2017-09-02

Excellent work. Professionally done. Keep it up!

Surajit Majumdar (author)2017-09-03

it means a lot to me :) Keep supporting me. Thank you.

Anshu AR (author)2017-09-02

Nice and neat!

Surajit Majumdar (author)2017-09-03

Thanks bro :)

LinoL9 (author)2017-09-03

Good. Have a shortcircuit protection?

Surajit Majumdar (author)2017-09-03

Thanks. yeah it has a replaceable fuse on the converter's board.

saeidhaghighipour1376 (author)2017-09-03

Exellent :)
would you explain a bit abut the circuit and how to design it,please?

2017-09-03

Thanks. Follow the wiring diagram :)

hpb (author)2017-09-03

You say the output can be 0-30V and output current can be 0-6A which means that at 30V and 6A you are putting out 180W of power. However your input is simply 12V, 3A which is 36W. This is simply not possible. With your inputs it's not possibly to get more than 1.2A output current at 30V. Taking into account regulator efficiency the output current at the rated 30V would be much lower. To get the full rated output you would need to put in at least 250W and that's a lot of power. Also I don't see any large heat sinks that can dissipate the kind of heat that rated output would generate. At that output I'm pretty sure you will burn the board without any active cooling.

Surajit Majumdar (author)2017-09-03

yeah, I completely agree with you. I can't get 180w of power. but according to the ltc3780 specification, it can provide up to 130w of power. Here I just mentioned the maximum range of current at limited voltage. Thanks for you advice :)