I found this thread - but I figure you probably did too. tubes in class d?
Seems like it could be done using some big sweeps as the switches?
Seems like it could be done using some big sweeps as the switches?
exactly what i had in mind....
i have lots of big sweep tubes...
but 6c33 seems a good candidate....
lots of hurdles to overcome...
i have lots of big sweep tubes...
but 6c33 seems a good candidate....
lots of hurdles to overcome...
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I wonder if anyone has thought of using the screen grid as the switch? After all, no screen voltage - no plate current, right?
that could work, and using tv tubes like the 6hf5 that only needs 120vdc to get the tube running big currents, why not?
under zero signal conditions, screens are at zero volts..
under zero signal conditions, screens are at zero volts..
You'd probably want to make the screen just positive enough for like 10mA to flow to avoid cathode poisoning when the music isn't playing...
Even when music isn’t playing, class D has some current flowing in the switches. You do have to charge the output filter, which takes some small fraction of the full load current. It’s all reactive so you don’t generate much heat. If you use a BCA topology, that idling current is half of the full load current. Far less worries over minimum cathode currents since the reactive current is high.
In order to keep it actually efficient, conduction losses have to be low, and plate voltage high, regardless of how you implement it. Sweeps with as high a cathode (heater) current you can get are the ticket. It might be a good use of those combination horiz output/ damper tubes since you will need freewheeling diodes. It will be closer to the intended application than what mot of us are using them for.
In order to keep it actually efficient, conduction losses have to be low, and plate voltage high, regardless of how you implement it. Sweeps with as high a cathode (heater) current you can get are the ticket. It might be a good use of those combination horiz output/ damper tubes since you will need freewheeling diodes. It will be closer to the intended application than what mot of us are using them for.
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I’m guessing these big tubes are needed to get low internal resistance for lower plate dissipation.
What an interesting idea though !
This thread hints at prior success but it’s an old thread and the link is dead: Blasphemy, I'm sure
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thank you guys, too bad that the links seems to be dead...
right now, i seem to go in favor of the screen grid drive..
right now, i seem to go in favor of the screen grid drive..
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