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Hoffman Amps Forum image Author Topic: rectify AC filament for DC on V1  (Read 1320 times)

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Offline joesatch

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rectify AC filament for DC on V1
« on: April 11, 2025, 09:17:04 am »
My PT filament supply has a CT. I'd like to rectify this for DC on V1 (rest AC).  If i use an elevated DC for the CT will this diagram work correctly?  the CT will be going to +63vdc but then the rectifier will reference that for ground?  use a FWB rectifier?


Offline joesatch

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Re: rectify AC filament for DC on V1
« Reply #1 on: April 11, 2025, 09:27:01 am »
i have seen this as well. what are all those big caps doing?

Offline Merlin

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Re: rectify AC filament for DC on V1
« Reply #2 on: April 11, 2025, 09:29:54 am »
It will work

Offline Merlin

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Re: rectify AC filament for DC on V1
« Reply #3 on: April 11, 2025, 09:32:13 am »
i have seen this as well. what are all those big caps doing?
They're trying to have a sort of balanced AC reference to ground after the rectifier. I don't think those caps will do anything very useful but you can try it (but they would need to be rated to withstand your elevation voltage).

Offline joesatch

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Re: rectify AC filament for DC on V1
« Reply #4 on: April 11, 2025, 11:10:49 am »
i have seen this as well. what are all those big caps doing?
They're trying to have a sort of balanced AC reference to ground after the rectifier. I don't think those caps will do anything very useful but you can try it (but they would need to be rated to withstand your elevation voltage).

what about cap rating with your diagram?  do they need to be 100v caps?

Offline Merlin

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Re: rectify AC filament for DC on V1
« Reply #5 on: April 11, 2025, 12:16:10 pm »
C1 needs to be rated for the elevation voltage. The other cap is only across the DC heater (I assume 6.3V).

 


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