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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: Optimizations w/ Triode ST35 Power Transformer posted by Jim Doyle on October 7, 2006 at 22:59:05:
Jim,In "El Cheapo", we want a B+ rail in the 350-370 V. range, as that puts an "ideal" 200-220 V. on the 12AT7 plates. The large forward drop in a 5R4 is advantagous, as the amount of waste heat from dropping resistors is kept small. The Hammond 266M5, will do NICELY to power the 5R4 filament.
The paired 6.3 VAC windings on the ST35 power trafo don't get wasted. One of those windings is quite capable of supporting 2X 12AT7s and 4X 6V6s. The 2nd 6.3 VAC winding would power the B- rail using a 1/2 wave parallel voltage multiplier. A stack of 7X 100 PIV/1 A. Schottky diodes should be quite sufficient to overcome the losses introduced by a pair of RC filter sections following the multipler. Caps. and diodes cost less than chokes. The B- draw in "El Cheapo" is only 12 mA. RC, as opposed to LC, filter sections should be OK.
Eli D.
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- Re: Optimizations w/ Triode ST35 Power Transformer - Eli Duttman 03:53:06 10/08/06 (0)
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