Quote:
Originally Posted by vortalexfan
I'm curious, if I were to use some 1.2V NiMH rechargeable D batteries to power the filaments in this radio (2 1.2V batteries in series would give me 2.4V roughly) what kind of diode or what size of dropping resistor would I need to drop the extra .3V to get the voltage down to the 2.1V I need for the tube filaments?
Or would it not matter in this case?
Thanks for your help.
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Any silicon diode such as the 1N400 series will drop around .6V which in my book will be close enough. I'd go so far as to suggest that two Alkaline batteries in series with the same diode will be close enough too. If you're worried about a few tenths of a volt, then put two diodes in series and when the batteries run down you can short across one and get any remaining life out.