Toroidal Transformer additional windings

[audiorookie]

Hi all.

I have a toroidal transformer with two secondary windings, each giving a 38V output. I will connect these in series to give me +38V, 0V and -38V. I am just wondering if anyone knows if it is possible to add extra windings over the top of the insulating layer of the toroid, from the 0V point, to give, say, +/- 15V? I would use this for an op amp in the preamp stage. Is this a possible way? Or am I completely heading in the wrong direction?

Thanks.

 

[Peter Daniel]

Yes, it is possible., I did that in this design: http://www.diyaudio.com/forums/audi...ip-amp-kits-dacs-chassis-109.html#post1491214 and it worked perfectly fine.

 

[audiorookie]

Thanks for your reply, I will give it a go then!

 

[AndrewT]

0.6mm diameter enameled copper is perfect for low current windings.
The 0.28sqmm can give upto 0.9Aac of continuous output.
That would be ~400mAdc of continuous current after the bridge rectifier and ~1mF of smoothing.

0.6mm is easy to straighten and to wind. A 500gm reel has a lot of metres on it for many projects. It even makes very good air cored inductors to experiment with CLC supplies.

 

[TonyTecson]

if the middle of your torroid is potted, you will have to remove it first...wind a test coil of say ten turns to determine the turns per volt...since volts/10 helps you with the number of turns required,.....

if you want +/-15volts i assume that that is regulated so you will need at least 15-0-15volt ac winding....wire will be small so that you can do bifillar winding.....