How to Build SMPS Transformer | Home Make 12V 10A Switching Power Supply

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With the transformer from old computer PSU. I try to make 12V 10A ( SMPS ) at home. I use SprintLayout for make PCB and iron method for make PCB board. In this video you can see me windings the SMPS transformer

For easy make PCB you can download my gerber file below and upload to JLCPCB.COM for make PCB online

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Step 1: Design the PCB

I use SprintLayout one of Rusia electric software for design PCB and print it to calendar paper. I always use calendar paper for print PCB because it cheap and good quality

Step 2: Make a PCB by Iron (press) Method

The first we need to cut the PCB exactly the PCB we print on calendar paper. After that we use the iron press to the PCB about 5 minute at maximum temperature

Step 3: Complete Make PCB

We put the PCB into water about 5 minute. After that we take the paper out and put it to FeCl3 liquid for 15 minute or more...then put to water again and clean it.

Because make the PCB take alot of time so for easy you can make PCB online. I usualy make PCB online by upload the gerber file to JLCPCB.COM for get PCB only 2$ for 10PCB. All file of my project include gerber file below.

Step 4: Drill PCB and Solder Component

Make the hole for PCB and solder component. I had attach the layout picture you just put the component to exact position.

List of component below.Your can order online them from LCSC.COM

Fuse 5A

Capacitor 275/250V

AC filter

Brigde diode RS507

Resistor 150K

Cacpacitor 150uF/450V

MF275 5D9

Resistor (27k )33K/2W

Mosfet 20N60 x2

Resistor 27ohm X2

Capacitor 224/100V

Diode UF4007

Diode 1N4007

Diode MBR20100


Resistor 15K

Capacitor 102

Capacitor 100uF/16V

Capacitor 105/600V

Resistor 4K7

Led 5mm

Resistor 2k2/2W

Capacitor 2200uF/50V

Choke and transformer heatsink we can take from old computer PSU

The Transfomer we need windings modify.

Step 5: Take Out the Old Wire From Transformer and Rewindings

Put the transformer to hot water in 5 minute. after that we can get the ferrite core. windings the transformer we use 0.4mm wire with primary 40T and secondary 5T for get 12V output. At the output with big current we use 6 wire together. Each layer must to use insulation tape

Step 6: Solder Transformer and First Test

Solder the transformer and test the circuit. In the first test we must connect with 60w/220v light bulb before plug to 220V. If the circuit fail the light bulb will on and we safety



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    21 Discussions


    1 day ago

    Your project looks good, I have no problem with it.
    It isn't regulated though (Just an observation, not a problem). It is still good as a proof of concept project though.

    antonio ivanf

    Question 2 days ago

    Hola, hice la fuente pero cambié la relación de espiras en secundario (16+16T) , ya que necesitaba 90Vdc, pero solo obtuve 54Vdc.
    Creo que debía haber hecho 40+40T?
    Por otro lado, en el pin 5 y 7 del IC que tensiones debo medir? En ambas iguales?


    Question 2 months ago

    Hi , I want to make a amps so I don't know about layout pls tell me


    3 months ago

    Hi, I have a question
    What is the voltage of the circuit?


    4 months ago

    Hi and good day. Very interesting and unique topology as i see on your schematic. Looks like a common half bridge but uses one high voltage capacitor and not two as usual. I want to change your circuit to form a 20V 6A smps (EE35 from old but working...250W ATX supply). Can i use the half bridge equations (factor of 0.5 X forward results) to calculate winding turns or use the forward topology ones as is. Thank you anyway.


    6 months ago

    Hi, I would like to know if this source would work
    with 110 VAC input or if you have to make some modification.
    Thank you


    11 months ago

    Heyyyy!!! thats a great idea to print the pcb on Calendar paper. and also to cook the old transformer to remove the glue etc. Thanks for sharing.

    1 reply

    1 year ago

    Is it your own design of SMPS?

    Can you supply a schematic please? It would be good see how it works and not just follow a construction guide.

    I have a box of old ferrite core transformers I wanted to open, thank you for showing the method!

    2 replies

    Reply 1 year ago

    Sorry for the late reply. This is design of SMPS. I use IC IR2153 with R=15k and C= 1n it run at 47kHZ. Schematic below


    1 year ago

    Nice instructables. I'm really missing the part on how you came up with the schematic (and the schematic itself). You had a design target, how did you achieve it. There are really good I instructables on toner transfer etc, so you can just link to them. What makes this ible unique is the purpose of the electronics. That's at least why I came here - I wanted instructions on how to translate the design target (12V, 10A) into a circuit.

    1 reply

    Reply 11 months ago

    The title of the instructible is "


    so you were expecting more than that? there are plenty of 12V/10A p/s designs in YouTube.

    (sorry for the large CAPS font; i merely copied and pasted the title)


    1 year ago

    Good project! I like the ferrit/bobin extraction.

    You can add a schematic diagram for reference.

    1 reply

    1 year ago

    Nice project. Thanks for sharing. where is the schematic? How did you calculate the turns on the primary? you have 20+20 turns = 40 Turns. what is the frequency of operation? how big is the core? part number? Please explain. Thanks

    1 reply

    Reply 1 year ago

    I use IC IR2153 with R=15k and C= 1n it run at 47kHZ. The transformer take from old computer PSU with EE35 core Schematic below