Newbie toroid transformer two secondary question.

Hi! I have a toroid transformer with two secondary (2x15v), but i will only use one of them (G7 mic). What do i do with the other secondary? Should I just insulate the conductors separately (which I think is the way to go) or do they need to be connected in some way?

Just want to be sure so I don´t burn something up...

Thank you!

//Martin

You could parrallel the two windings to give double the va
of a single winding,just make sure the windings are in phase ie
start and finish of the first winding conections
joined to start and finish of the second windings
start 1 connected to start 2
finish 1 connected to finish 2
=double va rating of single 15v winding

Thank you s2udio! But my transformer is rated 220v 2x15v 30VA, and what is needed is something like 5VA. Can it be to much if I parallell the windings? And just to know, is it ok to not use one of the secondarys at all (insulate the conducturs of that winding) or will that hurt the transformer?

Once again, thanks for your quick answer! :thumb:


//Martin

The circuit draws as much current as it needs, there is no danger having a too large transformer. Paralleling the secondaries will somewhat reduce heating and regulation, so this might be advantageous. Leaving one open is possible.

Samuel

Thank you all for your answers, will hopefully power up my very first DIY tonight! :grin:

Cheers!

//Martin

Not only should you make sure that polarity is right when paralleling windings, perhaps do a sensitive ohm meter reading to make sure they are exactly the same number of turns... if the windings are different number of turns they will fight each other. A precision voltmeter reading under power of each winding alone might be a better confirmation of number of turns.

If you have more power available than you need, I see no problem with just insulating the terminations and leave them float, or combine after rectifier diodes so they will always share even with small differences.

JR