mini tubes

[Eric Barbour]

>>For those interested in Eric's comments about miniature tubes,
>>here's a photo of three miniatures I have, along with a chip
>>as reference.
>>http://www.blaze.net.au/~sasami/synth/valves.jpg
>>The writing is a bit hard to read, but I think they say
>>Phillips 
>>Z70U 

This is probably a Z700U. Subminiature gas-filled switching triode 
intended for use in digital logic circuits. A historic tube. Used in the first
ever all-electronic desktop calculator, the Sumlock-Comptometer
"Anita" of 1962. (yes, that's right, the first electronic calculator
was all-tube!!.......I know this because the next issue of VTV will
feature an article about the Anita.......it contained DOZENS of
Z700Us......)

>>(long thin tube)
>>GX0
>>TKP
>>3V4504/KB/PH/00

Not sure what this it--it IS another subminiature tube (not
a miniature). It LOOKS like a version of the 6977/DM160 
fluorescent indicator tube. Was intended originally as a
tuning indicator for battery radios, and was marketed as
a logic indicator for computers. These things are cute--they are
sensitive enough to drive directly from any solid-state
circuit--one of my tube synths uses a 6977 as the LFO
rate indicator.