Just picked up a 1930s Battery operated Coronado

[dieseljeep]

Originally Posted by vortalexfan

No but someone else on here said to connect 2 D cells in parallel to get the voltage I needed for my filaments, you just happened to reply when I asked about how to connect batteries in parallel.
Anyways Rechargeable NiMH batteries are 1.2 Volts which if I connected 2 of those together I would get 2.4V which would be the correct voltage I need for the tube filaments, and they make NiMH Rechargeable D cells that are as high as 12,000 mAh, which would be more than enough juice to power the filaments.

I'm guessing the oscillator isn't running because the tubes aren't getting enough filament juice.

Those tubes aren't that easy to source. They only used them for few years.
The 1C6 can be replaced with a 1A6.
I checked over my 2 volt battery set. At the time, I built the power supply using a transformer from a scrap VTVM. I didn't have a regulator chip at the time, so I just used discrete components.

[vortalexfan]

Originally Posted by dieseljeep

Those tubes aren't that easy to source. They only used them for few years.
The 1C6 can be replaced with a 1A6.
I checked over my 2 volt battery set. At the time, I built the power supply using a transformer from a scrap VTVM. I didn't have a regulator chip at the time, so I just used discrete components.

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.

[Kevin Kuehn]

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.

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.

[vortalexfan]

Originally Posted by Kevin Kuehn

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.

I've got several 1N4007 diodes would those work?
Would I tie the diode across the negative or positive lead of the battery clip?