From: bill.sloman@ieee.org   
      
   On 31/12/2025 3:03 am, john larkin wrote:   
   > On Wed, 31 Dec 2025 00:36:38 +1100, Bill Sloman    
   > wrote:   
   >   
   >> On 30/12/2025 2:58 am, john larkin wrote:   
   >>> 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.   
   >>   
   >> Seems unlikely.   
   >>   
   >> https://apps.dtic.mil/sti/tr/pdf/ADA195556.pdf   
   >>   
   >> "The concept of a continous channel electron multiplier was developed   
   >> near the end of 1950. The invention was that of G.W. Goodrich of the   
   >> Research Laboratories Division, Bendix Corporation."   
   >>   
   >> The original application was for night vision googles. Cambridge   
   >> Instruments used them as electron multipliers in their electron beam   
   >> microfabricators. They had to be replaced every six months, but that was   
   >> tolerable with a million dollar machine.   
   >   
   >   
   > This is what google says:   
   >   
   >   
   > AI Overview   
   > The concept of the continuous channel electron multiplier, or   
   > continuous dynode, was first proposed by American physicist   
   > Philo T. Farnsworth in 1930,   
      
   He clearly didn't reduce the idea to practice,   
      
   > with early prototypes and active   
   > development occurring in the 1960s, particularly with work by Russian   
   > scientists like I. Pesyatsky and later commercialized into   
   > microchannel plates (MCPs).   
   > Key Contributions:   
   >   
   >      Philo T. Farnsworth (1930s): Proposed the fundamental idea of   
   > using a continuous, hollow resistor coated with secondary-emissive   
   > material to amplify electrons.   
   >   
   >      I. Pesyatsky (1940s): Created one of the first working prototypes   
   > of the microchannel plate (MCP) structure.   
   >   
   >      1960s Development: Significant technological advancements by   
   > various groups led to the modern microchannel plate, a matrix of these   
   > continuous dynode channels, as described in this University of Chicago   
   > PDF and this ScienceDirect article   
      
   Rather ignoring the commercial realities.   
      
   > Philo also achieved nuclear fusion around 1965.   
   >   
   > https://en.wikipedia.org/wiki/Fusor#History   
      
   But not in a way that could be used to produce energy.   
      
   It is apparently useful as a neutron source.   
      
   --   
   Bill Sloman, Sydney   
      
   --- SoupGate-DOS v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)