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can I use 12v to run 6C33C tubes???

Ketje

Member
2012-12-19 7:24 pm
Flanders
I am gathering parts for 6C33C OTL amp and not finding a lot of 12.6v filament transformers to heat the tube but I've found a lot of 12v transformers.

I want to use old potted xformers so looking at the old stuff on line. I'd like to use 4 xformers instead of one big one.
Looks OK , 2 x 5.7 = 11.4V minimum.
Mona
 

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02GF74

Member
2010-07-13 1:38 pm
depends on the VA of your transformer.

12 Vac is since wave with 17 V peak, if you draw less than the rated VA, there may be enough 'reserve' in the transformer to give a higher dc voltage.

If say you have a 12 VA transformer then that is able to supply 3x the current you need so will be able to give a higher voltage I reckon; use a 7812 regulator with diode in the middle pin to give output of 12.7 V.

This is what I', planning to do. albeit at half the current you are looking at. Will update once I try this out.
 
depends on the VA of your transformer.

12 Vac is since wave with 17 V peak, if you draw less than the rated VA, there may be enough 'reserve' in the transformer to give a higher dc voltage.

If say you have a 12 VA transformer then that is able to supply 3x the current you need so will be able to give a higher voltage I reckon; use a 7812 regulator with diode in the middle pin to give output of 12.7 V.

This is what I', planning to do. albeit at half the current you are looking at. Will update once I try this out.
Pointless, IMHO, there's no real reason not to use AC on the 6C33C heaters. At 6.3V and 3A for each half, a 7812 just won't be able to deliver the current, even with the two heaters in series. The valves generate enough heat without putting even more into a regulator. I don't know where you get 12VA from - it's over 36 per tube.
 
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TonyTecson

diyAudio Moderator Emeritus
2003-05-29 2:57 am
Maybunga, Pasig City
Pointless, IMHO, there's no real reason not to use AC on the 6C33C heaters. At 6.3V and 3A for each half, a 7812 just won't be able to deliver the current, even with the two heaters in series. The valves generate enough heat without putting even more into a regulator. I don't know where you get 12VA from - it's over 36 per tube.

agreed, no point to use dc on an indirectly heated cathode...

In fact, the key word is "nominal" , would not be surprised that your "12V" transformer actually is 13V or more unloaded, even 14V.

+1.....:up: