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ampage archive
Vintage threads from the first ten years
Re: AC vs. DC
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 9/10/1997 1:47 PM |
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Bruce C |
Re: AC vs. DC >And for better results reference the supply to about 30vdc instead of ground. Paul, can this 30vdc be obtained from the B+ supply with a simple voltage divider, say, 90K and 10K resistors (for B+ = 300v)? Or would this introduce hum into the plates? |
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| 9/10/1997 6:25 PM |
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| PAUL C | Hey Bruce, If you put the divider after a couple of the main filters the ripple should already be out of there so you wont get any hum. I'd start with about a 220k res on the top and dink with the bottom value so as not to have to little res. to ground after a filter cap. That'll play hell with the B+. One other benifit of doing this is that the heaters don't like it when the cathode is to positive. This is really a problem with cathode followers and cathode biased outputs. The heater can actually "arc" to the cathode if the voltage reference to ground is 100v or over. Putting a pos. reference on the heaters will stop this. Later, PAUL C |
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