I've just finished rewinding an old toy transformer, I think it had 3-5-9-15V/1,2A output, but what I wanted, is a center tapped +/- 12V output to use with a pair of uA7812-7912 regulators, in a power supply like this:
Build your Gadget: Dual Voltage Power Supply by 7812 and 7912 regulator
I used 2 identical secondary coils(0,55mm wire) coming form 2 old 12V/1A wall transformers, and I wound them on bifilar (both wires at the same time) on the empty bobbin.
I placed a 500mA fuse on the primary side and tested it out.
From the center to each end I get 12,4-12,6Vac, but from end to end I don't get any voltage..
is this because it's bifilar and I made both start windings into the center tab?
If that's the case, is the solution then to take 1 start and 1 end from each wire and make that the center tab, or do I have to redo it, one wire at a time?
hope my Q's makes sense, and remember.. there are no stupid questions
Regards.