From: jl@glen--canyon.com   
      
   On Mon, 29 Dec 2025 11:52:28 +0000, liz@poppyrecords.invalid.invalid   
   (Liz Tuddenham) wrote:   
      
   >john larkin  wrote:   
   >   
   >> On Sun, 28 Dec 2025 14:23:50 -0500, bitrex  wrote:   
   >>   
   >> >The 6AC10 tube is kind of like 3 12AT7s in the same package, pretty sure   
   >> >everyone has one of those in their junk box..   
   >> >   
   >> >But the transconductance of a triode is wussy, so adding a couple low   
   >> >voltage transistors makes a better regulator than you could get with   
   >> >tubes alone. The PSRR is not too shabby for the parts count, better than   
   >> >you could do with the two other triodes in a traditional diff pair and   
   >> >then you'd want a current source for the pair and bla bla bla.   
   >> >   
   >> >   
   >> >   
   >> >You could use an 0B2 for the Zener for that real vintage feel. And if   
   >> >you stick the optocoupler and transistors underneath the compactron (it   
   >> >gets toasty) your regulator is now also "thermally compensated"!   
   >>   
   >> When transistors were just becoming affordable, there was a last-gasp   
   >> burst of effort to save the tube industry. There were compactrons,   
   >> nuvistors, cold-cathode tubes, tubes that would run at 12 volt B+.   
   >   
   >It was a very long time before the performance of transistors caught up   
   >with Nuvistors.  In high radiation and EMP situations, I don't think   
   >they have yet.   
   >   
   >Before transistors began to compete, valves for car radios used +12 on   
   >the anodes but they also used either 0v on the first grids to assist the   
   >electrons out of the cathode or +12v to drag them out.   
   >   
   >In outer space, where the vacuum is 'perfect' and solar radiation could   
   >be directed onto a sheet cathode, new types of valve might begin to make   
   >sense.   
      
   Philo Farnsworth was a cool guy. He invented the image dissector tube,   
   the Farnsworth Fusor, and did some interesting multipactor work.   
      
   The perfect vacuum in space has some hazards to power RF circuits that   
   you don't get here.   
      
   I think he invented the microchannel plate too.   
      
      
      
      
   John Larkin   
   Highland Tech Glen Canyon Design Center   
   Lunatic Fringe Electronics   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)