# microwave oven transformer modification

#### Cavidex

Joined Feb 19, 2023
28
I have a microwave oven transformer and I need to modify it so that i'll be able to use it on my project ( hydrogen generator with electrolisys). How many turns do I need to get around 60amps at 3v? which is the most cost effective way to make it go from AC to DC?

#### Dodgydave

Joined Jun 22, 2012
11,375
The current depends on the thickness of the copper wire ideally you need 5 Swg , number of turns would be about 3 to 5 to give about 3 to 5 V.

Joined Jul 18, 2013
28,831
You may need to wind a few turns on to establish the turns/volt, generally around 4t/v for Micro TXR
Bridge rectifier, you may need a few more turns to counteract the volt drop across the rectifier.

Joined Jan 15, 2015
7,580
Sixty amps? Hope you have some heavy gauge wire. Consider your current when winding a secondary. Next you don't mention your primary voltage?

Ron

Joined Jul 18, 2013
28,831
Some use them for small spot welder applications, where the current is very high for just less than a second etc.

#### Danko

Joined Nov 22, 2017
1,858

Joined Jan 15, 2015
7,580
Some use them for small spot welder applications, where the current is very high for just less than a second etc.
There should be a book published "101 Uses for a Microwave Transformer".

And a heck of a lot lighter.

Ron

#### Cavidex

Joined Feb 19, 2023
28
thx for the replies. How do I turn it from AC to DC at that high of a current?
edit: the primary runs on 220vEU standard

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Joined Jul 18, 2013
28,831
Bridge rectifier, you can get individual threaded stud mount for a lot higher current than that, , mount them on a heat sink.
I don't trust SMPS for that current, I never use them for anything if I can help it.

Joined Jan 15, 2015
7,580
thx for the replies. How do I turn it from AC to DC at that high of a current?
edit: the primary runs on 220vEU standard
With high current stud mount diodes and when looking at your transformer AC out allow for the forward voltage drop of your full wave diode bridge. Using high current stud mount diodes you want two with stud cathode and two with stud anode. You never did mention your mains voltage? That's your transformer primary voltage. A Google of "High Current Stud Mount Diodes" should be a good start.

Ron

#### ApacheKid

Joined Jan 12, 2015
1,697
I have a microwave oven transformer and I need to modify it so that i'll be able to use it on my project ( hydrogen generator with electrolisys). How many turns do I need to get around 60amps at 3v? which is the most cost effective way to make it go from AC to DC?
Don't use it, they are incredibly dangerous as this engineer explains.

Joined Jul 18, 2013
28,831
Amazon, 100amp rated \$20.00

Joined Jan 15, 2015
7,580
I don't trust SMPS for that current, I never use them for anything if I can help it.
Same. I think where they make them their amp is about 0.5 of our amp.

Ron

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Joined Jul 18, 2013
28,831
Don't use it, they are incredibly dangerous as this engineer explains.
That article is around the use of using the Very HV secondary, in this case it would be prudent to remove the HV secondary and wind on the very LV of a very few turns.

#### Cavidex

Joined Feb 19, 2023
28
ok so I need a bridge rectifier to get the dc but it'll be too high of a voltage in output. how do I reduce the voltage of the dc output?
again the primary coil runs on 220V

Joined Jul 18, 2013
28,831
You need to remove the HV secondary and wind on a suitable No. of suitable gauge wire.
Most dismantle the transformer by stripping out the EI laminations and remove the secondary as well as a magnetic shunt that is present. Re-assemble after winding.
There are many YouTube videos out there of those that did similar to the type you want.
Normally you would wind on one layer of turns to ascertain the Turns/volt you need for the secondary,
What is the end use?

#### Cavidex

Joined Feb 19, 2023
28
on another note I scrached in a couple of spots the primary coil. can I use nail polish as isolation?

Joined Jul 18, 2013
28,831
How did you expose the primary?

#### Cavidex

Joined Feb 19, 2023
28
I already removed the secondary coil and I still need to find out the turns/volt of the secondary. now I can't use the transformer so i'll see the ratio in the following days