Mini Bench Power Supply - Vintage Style

I've had too many requests about my mini power supply, so i made instructable for it.
I’m in a progress of building new 2 channel power supply, but due to ongoing pandemic the shipping is slow and items keep disappearing. Meanwhile i decided to build temporary and easy PS from parts i had already laying around.

Main goals where:
- Easy to build
- Cheap parts and modules
- Easy to upgrade and modify
- Look nice on the workbench

Step 1: Main Components

80W DC-DC Buck converter module - Aliexpress
7in1 OLED Multifunction Tester - Aliexpress
External Power Adapter 12v/24v - Aliexpress
Multiturn Potentiometers (1x100k, 1x1K) - Aliexpress
16mm metal push button with LED (12v/24v) - aliexpress
Toggle Switch (6pin for extra indicator) - Aliexpress

Output terminals to your liking. I added DC jack and speaker terminals just in case. Outputs are all connected.
Banana Terminals - Aliexpress
DC jack - Aliexpress
Speaker Terminal - Aliexpress

I like to see, if power is connected to output, so i used extra indicators. Any led will do, but i had some nice looking indicators so i used those.
Indicator LED - Aliexpress

Depending on your indicator/LED you might need to use current limiting resistors.
Standard led > 470 OHM for 12V input power, 1.2 Kilo-ohm for 24v.

It's good to add extra security layer by using somekind of fuse. I used standard 5x20 mm fuse.
Fuse holder - Aliexpress

Step 2: The Encasement

I love woodwork so in my case my encasement is made from wood. I used scrap pieces of oak glulam i had. Some sawing, routering, drilling and sanding later i had myself simple, but nice looking box. I used router to give it rounded appearance, something like vintage devices/radios had.
I used teak oil as finish, added some rubber feet to raise it a little and sop it slipping and finally used furniture vent hole covers i found online.

Vent covers - Aliexpress

Step 3: Front and Back Panels

I designed my panels in illustrator. Tried to imagine the panel's design and ergonomics. Tried many many layouts until i got to the point i was almost happy. It's good to print it out and see layout in it's actual size/proportions.
If happy with the design you can use printout as a template to mark your drill holes etc.

In my case panels are made out of scrap acrylic glass. Sanded and spray-painted with black matte color.

Step 4: Electronics - Buck Converter

80w DC to DC Buck Converter (qs-1212ccbd-80w) is at the heart of this power supply.
It's cheap, has some useful features and works well for this type of a device.
It keeps constant current and voltage, has short-circuit protection, over heating protection and adjustable under voltage protection. Can be used to charge different types of batteries. What more can you ask from module that costs less than 4.- EUR?

We have to modify a little to ise it in our project though:
1. Remove/desolder potentiometers for 'Constant Current' and 'Constant Voltage'
2. Solder pin headers or wires for new potentiometers.
3. Optionally you can bring out the indicator LED's to the front panel as well. I soldered some pin headers for LED's as well.

I used multiturn potentiometers for better accuracy. 1K ohm for CC and 100K ohm for CV.

Step 5: Electronics - Final Assembly

In my case i used 12V input power, bu you can use 24v as well, just keep in mind LED current limiting. I used external power supply to keep encasement dimensions smaller.

Input power is used to power buck converter, indicator LED's, power button LED and Amp/Volt meter. There is 3A fuse between input and power on/off switch as well.

Buck converter's output is connected through multimeter to toggle switch. I use 6 pin toggle switch so it can power the output and indicator LED separately.

I used 3 different connector at the output jus in case. Bananas, speaker terminal and DC jack, but i never used anything other than a bananas :)

Most of the connections are made using spade connectors or dupont wires (+ one wago connector). It's easier to modify, upgrade or fix the power supply this way.

Step 6: Conclusion

At first i thought that i over designed the power supply, especially as it was meant for temporary power supply. But now I'm happy that i spent some extra time on the design and smaller details. It looks nice on my workbench, everyone always asks about it, and by now i built all my other tools in the same style/design key.

I'm using it almost daily for small test and experiments and had no issues with it. Ive been using it for 6 months now, so not so temporary after all (still waiting for some parts for my new large power supply).

Comments

[GavinM11]

Would you be able to add a photo of your toggle switch wiring?

[inspiredStudio]

Step 5 has the wiring diagram? Basically it just connects the booster output to the power supply output.

[RunningtoBunnings]

I really love this instructable! I've been needing a bench supply for a while and when I came across this instructable I decided that there was more to be learnt in making one than simply purchasing one. From reading other comments I understand that you intended to add a dummy load but ultimately decided against it. How would I go about making one for this project?

[jonahlait]

Just a few questions!
1) Why do you have a blue and a black voltage board in your opening parts photo?
2) Also what are the 4 leds for? One led under the screen shows the power is connected, but the other one? And the two by the toggle switches what are they for?
3) Finally what’s the purpose of the two toggle switches? 1 turns the power on for the connectors, but the other one?
4) Also the back of my 7 in 1 is slightly different, so how do I wire this in? I see on your diagram you only have one set of wires going from the buck to the screen, when it should be two set, one for voltage, one for amps.
Do you have a full wiring diagram?
thanks for your help.
👍

[inspiredStudio]

Something like this? I was looking somekind of meter for my higher voltage dc power supply and found this.

[inspiredStudio]

1. These where spare buck converters i had at the moment. When i took the picture i was still unsure witch one i was going to use.
2. LED's near the toggle switches are led's connected from buck converter, they are built in indicators for charging batteries.
2...3. At first i had planned to have built in dummy load for setting the current limit, but ditched the idea in the end, so now it has 1 spare switch and LED.
4. In my diagram i have 2 sets of wires connected to multimeter, I attached diagram below.

[jonahlait]

Thanks for that.
I wonder how I wire up the volt /amp meter I have then?
I seem to have 2 thin wires for power to the display, two thin wire for a temperature gauge, that’s the easy bit.
But then I have 2 screw terminals on left and two on the right? Both have a positive and negative marking on them.
I wonder how they connect?
Any ideas?

[inspiredStudio]

Google the specific model? Contact the seller? I have little experience with this kind of multimeters :(

[drwhitehattr]

Good health to your hands. Do I have a chance to learn the size of the well?

[gordonwh40]

Hi Just the sort of thing I was looking for. You say in your very good description that "If happy with the design you can use printout as a template to mark your drill holes etc". Where is the diagram to use as a template? That would make the project much easier for the person with little in the way of tools etc. Thanks for the great project.

[inspiredStudio]

This is the panel layout i settled on, i had something like 7 different ones,

[gordonwh40]

Thank you

[papaofmany]

Well done. Great job!
One question: Don't the visible screws on the top annoy you a bit (aesthetically speaking)? Why not have glued the top cover and close it with these screws on the bottom (and even possibly hide these under the rubber feet) ?
Thanks for sharing!

[inspiredStudio]

They do annoy me :D i didn’t know the temporary powersupply will look so good. But it's too late and i' am already building a new one. There's a lot of things that annoy me :D I’d like to have larger radius on the corners, outer and inner radius of the frame do not match, glulam wood has too sharp transitions etc... I really didn’t had any other wood in the correct dimensions at the time, at first it was just a box, so i routed down the edges, socket for the panels etc, and that ho it came to be.

[papaofmany]

Thanks for the honesty. I love it that, despite having some of the personality traits of a detail oriented person (Did I say perfectionist), you do not let that paralyze you and get to work with what you have. This is the way to go, one step at a time.
Cheers.

[inspiredStudio]

Tnx :)

[steersteer]

What is the second toggle switch for?

[inspiredStudio]

It was meant for resistive dummy load to check on the input power :) I'am not sure if i need it in this PS.

[steersteer]

ok, thanks

[Liam McM]

Looks spectacular! Looks like somthing from the 'diy perks' youtube channel.