transformer in parallel - help

[ackcheng]

hi, I am currently building an amp and my power transformer has not enough VA, I am just wondering if I connect 2 exactly the seem transformer in parallel, will I get double the power?

Thanks

[elizard]

if its for a stereo amp, you could always use 1 transformer for the left channel, and 1 transformer for the right channel ..

[Centauri]

.........and if its for a single power amp, then yes you can parallel windings. HOWEVER, they must be connected in phase - out of phase connection results in short circuit. I have also seen examples where separate bridge rectifiers were used, and resultant DC outputs connected together (this may be useful if there are slight differences between transformers).

Cheers

[Tubeee]

Hello there,

What if two identical transformers with single secondary output; say, 0-12V; parallel connect to configure to be center tapped 12V-0-12V. Any risk??

________>|<__12V
pri______<|>__
|_______ >|<__0V +
|________________|
|________________|
|_______ >|<__0V +
pri______<|>__
________>|<__12V

[officeboy]

I'm doing that now, works great. And it’s a great way to use super cheap lower rated transformers.

You can kind of see it here, 2 transformers in parallel, the 4 secondary wires running from them to the rectifying diodes.
http://home.comcast.net/~0fficeboy/a...s/photo_8.html

[Centauri]

Tubee,

If the primary windings in your diagram were connected identically in phase, then the output between the two 12 lines would be zero as the windings are out of phase. You need to connect the windings in series IN phase ie. 0V of top winding connected to 12V of bottom winding is centre tap.

This is a better way of combining transformers as any differences between each one does not matter.

Cheers

[richie00boy]

tubee,

That's connecting in series, not parallel...

[Tubeee]

officeboy,

thanks for your experiment. My original concept is to create a center tap before bridge not after and that will save one bridge.

Centauri,

If the primary windings in your diagram were connected identically in phase, then the output between the two 12 lines would be zero as the windings are out of phase.

You are right. My thinking was the same as yours but wrong in "drawing". Too bad..
What I am interesting is the difference between center tap (supposed to connect to ground) created in this configuration and in case of one center tapped transformer.
Will the center tap (ground) float or unstable?

richie00boy,

Forgive my language. The connection of primary is in parallel and the secondary is in series that I sould said.

[Centauri]

Originally posted by Tubeee
What I am interesting is the difference between center tap (supposed to connect to ground) created in this configuration and in case of one center tapped transformer.

No difference - this arrangement will behave exactly the same as single centre-tapped transformer.

Cheers