Sylvania 7155 & 6879 
Written by AnubisTTP on 2007-03-24  

Description

Devices included in this entry:

Sylvania 7155 computing counter (7 pin base)
Sylvania 6879 computing counter (7 pin base; pictured in thumbnail)
Westinghouse 6879 computing counter (7 pin base)


Sylvania's entries into the miniature counting tube arena, the 6879 and 7155 are tiny and quite unusual. Both tubes are packaged in a standard 7-pin T51/2 envelope with top nipple, and both use a common 7-pin socket instead of an obscure 13-pin socket like the slightly larger EZ10. Both tubes are designated for computer use, and have three non-common output cathodes at counts 8,9 and 0. The Sylvania 7155 is an unusual tube: a 100kHz double pulse bidirectional counter in miniature, and is one of the smallest, fastest dekatrons ever made, surpassed only by the most advanced Elesta and Soviet dekatrons. The 6879 is a slower neon-filled device, and is only rated for 5kHz.

Sylvania Decade Counter Tubes (PDF)

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Sylvania 7155 glow transfer counting tube.


The 7155 was shipped in a dramatically oversized carton, a size normally reserved for much larger octal tubes.


Westinghouse 6879 glow transfer counting tube.


Westinghouse's packaging for the 6879 is a more traditional nine pin tube carton.


Sylvania 6879 glow transfer counting tube. The Sylvania version of this tube appears identical to the Westinghouse example in construction, and was likely manufactured at the same factory.


Miniature dekatron size comparision. Part numbers from left to right:Elesta EZ10A, Westinghouse 6879, Sylvania 7155, Elesta ECT100, Soviet A108, Soviet A109.

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