Transformer pinouts help

Discussion in 'The Projects Forum' started by gordan, Aug 29, 2012.

  1. gordan

    Thread Starter New Member

    Aug 29, 2012
    Hi I recently found an old AC voltage stabilizer for refrigerator lying around. Its probably made in the 80s. It consists of a PCB with an op amp, couple of non functional relays with burnt out contacts and a heavy transformer with multiple taps on both sides. I've attached the pictures below. A continuity check shows that it has no shorts, but I'm really confused as to finding out which is primary and which is secondary. I've also included a diagram depicting an ohm check between different taps. Someone help me with it please!!!
    P.S I have a hunch that some of the taps were used to power the electromagnets in the relays, but I may be wrong. Help me out here please...

    Thanks in advance...
  2. DickCappels


    Aug 21, 2008
    For a case like this, you can drive one winding with the output of a low voltage transformer, such as 12 VAC and then measure the voltage on the winding to get an idea of the turns ratios.

    You used the word "stabilizer" in your description, so this might be some sort of higher tech transformer than I would guess, but if its an "ordinary" transformer (its pretty linear and doesn't saturate or resonate) then either winding can be the primary, but the risk is that if a winding that was intended to be a low voltage secondary is connected to the AC mains, the transformer might draw a lot of magnetizing current and that might be bad.

    Go cautiously, and if you aren't sure about what you have, you might be better off taking it apart for scrap. Magnet wire is very expensive these days.

    Also those epoxy transistors are genuine antiques -probably dating back to the early to mid 1970's.