Wanted: vacuum tube logic circuits - test-drb@ccmp.vtda.org

30 Aug 2008

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Subject: Re: Wanted: vacuum tube logic circuits
   From: William Blair <wbblair3 at yahoo.com>
   Date: Sat, 30 Aug 2008 07:58:29 -0700 (PDT)
     To: cctalk at classiccmp.org

William Donzelli wrote:

  I have exactly one 12U7 in stock. I have a few
12K5s, as
 well. 
I've now got a number of different dual triode tubes to try from a local electronics
shop that has a large collection of tubes from former TV and radio repairmen.  $1 each and
they have a B&K 707 tube tester to test them on.

  One thought about using space charge tubes for
logic - they
 might end up being slow as molasses. 
>From a message above, it looks like even a 6.3V plate voltage on a standard (not low
voltage) dual triode tube will work and I'm after a visibly slow (a few Hz at most)
multivibrator anyway with a binary counter circuit attached. 

Most all of the space charge tubes were optimized for 12V plates.  IF you can run
12V to 25V range you limit yourself less as even generic 12AX7s, 12ATs and 12AU7s
perform serviceably there.

Allison