Introduction: DIY Lab Bench Power Supply From Scratch

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Are you tired of powering your circuits with a lame,non rechargable 9V battery?

Do you wish that you cold afford a power supply?

If so,why don't you try to DIY yourself a power supply that can deliver up to 27V and 3A!

Step 1: Gathering the Materials

-A power supply with a fixed voltage(You can use the 12V rail of a atx pwoer supply or a laptop charger)

-Banana jack&plugs

-Volt and amp meter

-LM2577S LM2596S buck boost converter

-Some screws to secure the side pieces and wood glue


-3D printer(I printed just the front because the whole case would not fit but you can make it out of wood)
-Sodlering iron(or even better,a station)
-Hot glue gun

Step 2: Modifying the Power Supply

If you are not experienced,use a laptop charger or buy a lab bench power supply.This can be dangerous

You will need to shorten all the wires to a smaller lenght.Check where the most power is.In my case,it was on the 5V rail.We are going to use the 12V rail to power the module.Solder a 5ohm 5W resistor between the 5V rail and ground(or the rail with the most power).You will also need to solder the purpule wire to ground so the power supply will trun on.

After this,solder togheter all the yellow wires(12V rail) and all the black wires togheter.Connect those wires to the input of the buck boost converter.

Here is a not so fun story:
When I plugged in the power supply,nothing happen.I plugged it out and plugged it back in."BOOOOOOM" is what I hear so I got the power supply out of the wallet immediatly and used a phone charger insted. You can see in the picture above that the fuse has blown.BE CAREFUL!

Step 3: The Wiring

After you modified the power supply,hook up the yellow wires at the positive input of the buck boost converter and the black wires to the negative input of the buck boost converter.You will also have to hook up the thin red and black wires to the input of the buck boost converter.

Wire the lcd as shown in the schematic above:

-Thick red wires goes to the Negative output of the buck boost converter
-Thick black wire goes to the Negative output of the power supply(not the module)
-Thin yellow wire goes to the Output of the power supply&the output of the buck boost converter module
-Thin black and red wires go to the input of the buck boost converter(For power)

Step 4: The Case

At first,I wanted to 3D print the entire case but it wouldn't fir on my printer and splitting the parts would have take a long time to print.So I decided to print just the front and make the side,bottom and top pieces out of a thin wood.

I made a U shape piece ang glued it togheter with wood glue.I glued the bottom piece to the front panel.The U shaped piece would go into two of the power supply's screw holes,with a bit longer screws so it could keep the wood and the power supply togheter and another two screw holes into the 3D printed fron pannel.
I also added two screws on the other side of the 3D printed pannel.

Step 5: Fitting Everything Inside

Now,start fitting in the banana jacks(the output of the power supply),the switch to turn on/off just the output.screen,glue the potentiometers with a lot of hotglue,screw the side pieces in and you should be done.

Step 6: You Are Done!

Plug it in and hope that it doesn't blow up like mine did on my first try.