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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: 25Z6 voltage doubler questions posted by harley on August 16, 2006 at 18:49:40:
Hey Harley,Please note all of the cautions others described for line connected circuits - not for the casual in any manner. But isolation trannies are easily crafted using two identical, or near enough, trannies that can be salvaged from discarded equipment (one of the few goodies on older monitors). If you were to take two 120:16VAC trannys - for example - and hook the 16VAC windings in parallel you can feed 120VAC into one "primary" and produce an isolated 120VAC from the other "primary" - just continue to line ground on through. And while it is probably preferrable that you power your heaters from the isolated source if you can't find two trannies capable for supplying the entire load you can always power the heaters from the line - fused at both ends and totally separated from ground - and supply the B voltage supply from the isolated supply. And as long as the trannies have sufficient current capacity they don't have to be "exactly" identical - you could feed a 9 VAC secondary from a 12 VAC secondary and have a bit more than 120 VAC to play with should you wish to power your output tubes without having to cobble up a doubler.
If you were to go with a 50V rectifier, a 50L6 (50C5 lower wattage) output and a 12AX7 with a 20V heater you could eliminate all but 5V of dropping resistors - or you might find two trannies that put out 112V or so.
Rob
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Follow Ups
- Re: 25Z6 voltage doubler questions - Rob Mercure 09:08:53 08/17/06 (0)
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