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# Transformer

#### S-fr

##### Member
Hey there ,
I got a transformer that is 25-25-0 plus 12-12-0, both em are dual output i need to know if i can just connect em in this same order to get more voltage ik, at the end the total watts will be the same, and if that's possible, is this safe?

What is the power required, V and I ?

Transformer datasheet, post .

Regards, Dana.

IF (big if) the 25-0-25 group is completely isolated from the 12-0-12 group, then
.
.
.
.
maybe.

If the transformer is in fact 25-12-0-12-25. then a big NO.

ak

Hey there ,
I got a transformer that is 25-25-0 plus 12-12-0, both em are dual output i need to know if i can just connect em in this same order to get more voltage ik, at the end the total watts will be the same, and if that's possible, is this safe?
Post the resistance across the outputs. What is the resistance between the two 0V secondaries?

What is the power required, V and I ?

Transformer datasheet, post .

Regards, Dana.
Well its a locally made one so there no datasheet, and i need somewhere between 35-0-35 and 40-0-40

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IF (big if) the 25-0-25 group is completely isolated from the 12-0-12 group, then
.
.
.
.
maybe.

If the transformer is in fact 25-12-0-12-25. then a big NO.

ak
No, i check its myself its 25-25-0v, giving me like 49.8vac something and 12-12-0 and its giving me like 25vac

Post the resistance across the outputs. What is the resistance between the two 0V secondaries?
Like?? Both of their grounds???

We are trying to determine if the 12 V windings and the 25 V windings are galvanically isolated. What is the resistance between one of the 25 V wires and one of the 12 V wires?

a) multi-megohms or infinite

b) anything else

ak

do you mean like this? This is 1:2 centre-tapped. That won't give 35~40 out on each leg.

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Version A cannot be adapted for various voltages, version B can be added to get higher voltage. Measuring resistance from zero to zero on A will be a short, on B it will be infinite.

Version A cannot be adapted for various voltages, version B can be added to get higher voltage. Measuring resistance from zero to zero on A will be a short, on B it will be infinite.

View attachment 143381
Well i did the continuity test (ig thats what its called and it seems the zeros are separate as there was no beep from the multi meter, so its B

Post the resistance across the outputs. What is the resistance between the two 0V secondaries?
There is none, i check it with my multimeter and no continuity beep either

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do you mean like this? This is 1:2 centre-tapped. That won't give 35~40 out on each leg.

View attachment 143380
I am learning alot today it seems, but im sure my transformer isn't this one

We are trying to determine if the 12 V windings and the 25 V windings are galvanically isolated. What is the resistance between one of the 25 V wires and one of the 12 V wires?

a) multi-megohms or infinite

b) anything else

ak
Its isolated i confirmed it just now

No, i check its myself its 25-25-0v, giving me like 49.8vac something and 12-12-0 and its giving me like 25vac
Now the question is, does your meter read "True RMS" AC voltage, peak AC voltage or ...? Which meter are you using (brand and model number).

Now the question is, does your meter read "True RMS" AC voltage, peak AC voltage or ...?

For the low frequency, mostly-sine-wave output of an unloaded mains transformer, this is not an issue. In fact, this probably is what the meter is calibrated for.

ak

Now the question is, does your meter read "True RMS" AC voltage, peak AC voltage or ...? Which meter are you using (brand and model number).
I got a basic one thats is for general usage, uni-t 33b+

Note that the max current output of the two windings in series, is the the max of the winding with the lowest rating.

Now the question is, does your meter read "True RMS" AC voltage, peak AC voltage or ...?
All multimeters are designed to read the RMS voltage of a sinewave.
Since this is a transformer sine-wave output, whether the meter is average responding, calibrated to read RMS, or a true RMS meter will have a negligible difference on the value measured.

Note that the max current output of the two windings in series, is the the max of the winding with the lowest rating.
Sorry I didn't get that, like the two 12s in the 12-0-12?