'Radio Bygones' Capacitor Reformer Project

[Yorkie]

Might I make one minor suggestion?
Put a resistor across the unused winding of T2.
Alan

Thanks for reading Alan, and for your observations.

I'd wondered about that myself at the time Alan. I'm not too well up on transformers, but I have heard that it's not good practice to have unused secondaries. What current do you think that the used secondary should draw to keep it happy? EG, a 220R resistor across that unused secondary would draw 27mA. (only 0.16W).

But that said, it was commonplace for mains transformers for valve power supplies to have several secondaries - for example, for different voltage rectifiers - 4v, 5V, 6.3V - sometimes tapped, sometimes separate windings, some of which were unused. I've sometimes used two secondaries in series to double up the voltage, or paralleled them in phase to double up the current carrying capacity.

For anyone contemplating building that reformer, the most satisfactory and cheapest option for the mains transformer arrangement would be to use one rather than two back to back. For example, a mains transformer culled from an old AC radio with 240V and 6.3V secondaries.

David.