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# How many volts will this transformer configuration produce?

#### Athosworld

##### Member
I connected 6vac to the secondary of a 120 to 12 transformer, what should be the output voltage. I just know the shock was very painful.

#### Athosworld

##### Member
How many volts if i connect the same voltage in the primary of a microwave transformer?

##### Well-Known Member
Be extremely careful with a microwave transformer. If you connect primary
to its design 110/220 , you get ~ 2000 V of output. Spend some time researching
electrical safety, will serve you well. Its turns ratio then ~ 2000/120 =~ 16.6

Connecting to 6V would be ~ 6 x 16.6 =~ 100V.

There are several videos on youtube where folks are removing secondary and rewinding
to make welders, spot welders, battery chargers, all low V in the 10's of volts.

Regards, Dana.

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#### For The Popcorn

##### Active Member
You need to figure out how transformers work. It's simple math.

Say you have a 120v to 12v transformer. The ratio is 10:1. If you connect 120 volts to the primary, you get 12 volts at the secondary. Connect 50 volts to the primary, you get 5 volts out.

But if you connect 12 volts to the secondary, you get 120 volts on the primary.

If you connect 120 volts to the secondary, you'd get 1200 volts out of the primary....except that the insulation may not hold up, and you may get a fireball instead.

If you don't understand this simple concept, what you've been doing is dangerous. A 120 volt shock can kill. A 1200 volt shock will kill.

#### ChrisP58

##### Well-Known Member
How many volts if i connect the same voltage in the primary of a microwave transformer?
What is the output voltage when it's connected to 120 Volts?

Take that number and divide it by the normal input voltage. That will give you the turns ratio.

Then multiply the new input voltage by the turns ratio.

#### Diver300

##### Well-Known Member
But if you connect 12 volts to the secondary, you get 120 volts on the primary.

If you connect 120 volts to the secondary, you'd get 1200 volts out of the primary....except that the insulation may not hold up, and you may get a fireball instead.
When run at the usual frequency, most transformers will have the magnetic core saturate if the voltage is a bit above nominal voltage. Once the magnetic core saturates, the output voltage won't increase any more, but the input impedance of the transformer will drop.

Connecting a 120 - 12V transformer the wrong way to 120 V mains will either blow the fuse or burn out the 12 V winding.

You won't get a 1200 V from the output, and the waveform will be very distorted. You would certainly get dangerous voltages.

It's similar to if you run a transformer on the wrong voltage. If you connect a 240 V transformer to 120 V, you get out about half the normal voltage, as explained by others. If you connect a 120 V transformer to 240 V, it will take a huge current, even without a load. What happens after that depends on what circuit protection is in place.

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