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Calculating circuit current

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  • Calculating circuit current

    Hi all, I have a PT with 250V & 6.3V CT secondaries. it is also marked as 60MA, which I assume reefers to the HT, not the heater secondary. 60mA ain't an awful lot and I would like to build a Push pull. I have a number of valves available and was thinking two 6N2P (or 6AT6 and 6N2P) and two pentodes - I have a choice of 6M5, 6BQ5, 6AQ5, 6V6G, 6V6GT or 6P14P. But I think that any pair of pentodes would draw too much current for the PT to handle. I will use 1N4007 diodes for rectification.
    Which currents in the datasheet do I need to consider? Is it a simple matter of adding the anode currents for a given B+ for each valve (plus a bit leftover for safety) or do I need to take into consideration other components?

    The PT was in a radio with 5 valves @ If of .7A each.
    If I reduce the number of valves, does that give me back the power in the HT (36mA?).

    Or should I just stick to a little SE?

    Many thanks in advance. Again.
    It's not microphonic - it's undocumented reverb.

  • #2
    There may be a little leeway; you could possibly get away with using a pair of 6aq5s @ 70mA idle current, or bias them a bit cold. Alternately (I know they're not on your list) you could do p-p EL95 outputs; idle at 44mA, 52 mA at full honk for a whopping 7W out. Allow a couple of mA for each preamp/PI triode section.

    I wouldn't bend over backwards trying to design around this particular PT. You can get Weber's general purpose multitap PT for $35. 150mA and a wide variety of voltages.

    Nathan

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