From: liz@poppyrecords.invalid.invalid   
      
   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.   
      
   --   
   ~ Liz Tuddenham ~   
   (Remove the ".invalid"s and add ".co.uk" to reply)   
   www.poppyrecords.co.uk   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)