So how small are the transformers? Used like this the AC source to the bridge is pretty high impedance, so when you try to draw much current the voltage sags badly. 'Small' transformers often have poor regulation of around 15-20%; two in series is suddenly nearly 40% meaning that at the rated load current you'll effectively lose up to 40% of the off-load voltage. Guess what, it appears you do!
You need to either use grossly-overrated VA transformers, or two with much lower step-down ratios. If you don't have such things to hand in the bits box, I'd expect one approriate new valve transformer will be cheaper.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.