Dekatrons are decade pulse counters that indicate the current count by means of a neon glow around a pin. The glow transfers from pin to pin on each input pulse. They can be used as decimal dividers by taking the pulses from one pin as the input to the next stage.

They were some of the earliest fast counters, capable of speeds in the tens to hundreds of kilohertz, several orders of magnitude faster than the alternative relays. They were frequently used in radiation or other decade counters, but also in some early decimal calculators.

ECT100 bi-directional counting tube
This tube is used for decade counting, not as numerical display

GR10A side
GR10A in base

GR10A top

GR10A showing base configuration

Click pictures to enlarge
Thanks to Martin Forsberg for identifying this tube. For more more information, visit the Vintage Technology Association Website: .

See: .

© Andy Cowley 2008
Updated March 2015, DWK


Counting tubes