In Reply to: Problem with DC heater voltages posted by arnoldc on September 19, 2004 at 16:39:09:
Hi
You should get 1.41 of the secondary voltage, with the diode voltage drop AND the correct transformer.
Since the sec. voltage goes up, the sec. current must go down (there is no free lunch in nature)The actual formula is IDC=0.62 ISec for a capacitor input PS.
So, you need to over-specify the secondary current, otherwise the transformer secondary voltage will "sag".
Buy a xformer rated for double the tube's filament current draw and it should work fine.
Remember to float (do not ground) the DC supply, because the filament is the cathode for DHT tubes. The cathode resistor+cap are connected to the heater PS (-)wire.
I hope this helps
Good luck
Carlos
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Follow Ups
- Re: Problem with DC heater voltages - Carlos 09/25/0415:21:35 09/25/04 (0)