Wanted: vacuum tube logic circuits

[William Blair]

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.