Don't Miss

Custom Made Isolation Transformer

By on January 12, 2010

One of my ERG member from Iran that had bought my ebooks successfully built an isolation transformer with the help from his friend. This is the email he wrote to me:

“Hi jestine

Refer to your new  smps repair  book and the importance to have a isolation transformer  first i decide to buy one but i could not found any in the town ready to use  therefor the only way was to make one
by assistance one of my friend mr esmaili  he has transformer shop   he made one transformer 1:1 220 to 220 volt for me  and then i assemble  the other parts inside. and out side of  a metal box
i put voltmeter  range up to 250volts  and ampere meter  range up to 5 amp  on/ off switch /fuse  ac cord pilot lamp on the panel also i fixed the transformer with 4 screw in the bottom of the box 220 volt out let is on the front panel that is  safe 220 volts ground free total cost me 50 usd and from now i work in safety
thank you jestine


Here are the photos:

isolation transformer

isolation transformer



  1. John Preher

    January 14, 2010 at 5:46 am

    That is a really nice home made isolation transformers. I have seen some real beasts in the past. Many technicians I new would just take two of the exact same transformers and connect the secondary widings of the two transformers together to create one huge 1:1 transformer..LOL. I wish I hade one like in this picture.

  2. ravendra

    January 15, 2010 at 7:13 pm

    any tips for making variac at home ?



  3. admin

    January 15, 2010 at 10:27 pm

    Hi Ravendra,

    Sorry no tips, for Variac the best is to buy a ready made one.


  4. behzad

    January 17, 2010 at 12:14 am

    Hello john
    i am happy you like my transformer . makeone!. it is ez. i am here with you for help .ask me.

    • P. Pillay

      August 6, 2018 at 11:17 pm

      HI. This isolation transformer 1.1 220v I sure wood like to b
      would to build one, but don't know how. Pllay from south Africa. thank you.

  5. Waleed

    January 18, 2010 at 3:33 am

    I am looking for part to put this isolation transformer together but so far, I am having problem finding the 1:1 transformer. they keep telling me that it is custom made and it takes time and expensive. any idea where to get it?

    • shiekh

      December 3, 2013 at 9:32 pm

      How about pick any transformer (of sufficient power) and wire two back to back; that way you may be able to use whatever is lying around. If you pick two 220/110 transformers, you can also have dual voltage output.

      • Jestine Yong

        December 3, 2013 at 10:04 pm

        Hi Sheikh,

        Yes you can do that back to back connected.


  6. admin

    January 18, 2010 at 4:38 am

    Hi Waleed,

    Usually electronic shops do not sell the 1 to 1 ratio transformer. You need to go to transformer rewinding shop to ask them to make one.


  7. Songre Osmenep

    August 25, 2011 at 5:24 am

    Jestine, this a great project by Beh! and I definitely need to make one can you tell me how to go ahead and get the shop to make me one for 120 Volts or do I need to make a 220 volts? and if Beh can give me the parts list I will go get them and start on this project A.S.A.P Thanks....

  8. Songre Osmenep

    August 25, 2011 at 5:29 am

    By the way Justine if Beh makes these Transformers and sell I have no doubt we will buy them. I am just really impressed with the design....Kudos!!!!!

  9. admin

    August 25, 2011 at 6:47 am

    HI Songre,

    Yes he is good in the electronics related things.


  10. admin

    August 26, 2011 at 9:03 am

    HI Songre,

    It depends on your country. If your country is using 220v then get a 220v transformer.


  11. vanesh

    March 10, 2012 at 5:34 am

    Dear Jestine.
    You mention about the transformer rewinding shop. May i where can it?

    • Jestine Yong

      March 10, 2012 at 12:10 pm

      HI Vanesh,

      It is located at pasar road kl


  12. vanesh

    March 10, 2012 at 5:41 am

    sorry on my early comment. I didn't mention i from Kuala Lumpur.
    Thank you

  13. beh

    April 9, 2012 at 10:00 pm

    the part s of this isolation trans former all is shown the in the pictures and there is no any hidden parts the main part is transformer  .  this need to contact with such shopes that they make trans and order what do you want .that is all . to make and send this to others also would be very costly due to  a very heavy transformer the cost for shipping would to much i recomend you all to make one by your own in your town
    god bless all

  14. jake

    February 10, 2015 at 9:58 am

    Hi beh
    I like your isolation transformer. Can you tell me how you wire them.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.