Quince
Well-known member
The transformer has two heater windings that give 6.4 VAC RMS when loaded. I need to power the heaters of four EL34 tubes, so 6 amps total. If I want to do DC heaters, however, I can't seem to find any rectifier with low enough dropout to give me 6.3 VDC. If I put two heaters in series, and the transformer windings in series, then the rectifier dropout effect is cut by half and I do have sufficient voltage; however, in testing the heaters are not matched well enough and that worries me -- putting two heaters in series with the AC voltage I get 6.4 across one heater and 6.8 V across the other. Now, is it possible to do low dropout regulation that would force the voltages to be divided (so two regulators on top of each other, one parallel with each heater)?
The irony is I wound the transformer myself and didn't think to put an extra turn... as these are the bottom windings there's no way I'm taking it apart again.
The irony is I wound the transformer myself and didn't think to put an extra turn... as these are the bottom windings there's no way I'm taking it apart again.