From: user@example.net   
      
   On 12/28/2025 10:01 PM, 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+.   
   >   
   >   
   > John Larkin   
   > Highland Tech Glen Canyon Design Center   
   > Lunatic Fringe Electronics   
      
   The 6AC10 is an adorable lil tube, mine's Raytheon-branded but made in   
   Japan:   
      
      
      
   I don't really have a use for the "funky regulator" but I like the idea   
   of using an optocoupler to provide drive for the pass element of a HV   
   regulator, avoiding high voltage transistors or having to float op amps   
   and such.   
      
   I have one "tube bin" with some random stuff like the 6AC10 and some 12   
   volt tubes in it, even a Strobotron...at some point I inherited a couple   
   packs of 0B2 gas diodes.   
      
   Amazon/eBay sell these little boost modules for tube experimenters with   
   a HV output and a 6.3 volt output maybe good for an amp or so, they   
   really hate driving a gas tube directly as a load and the 0B2 flickers   
   like a neon Christmas candle, some nice noise/chaos on the 'scope too:   
      
      
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)