Dekatron (or Decatron, or generically three-phase gas counting tube or glow-transfer counting tube or cold cathode tube) is a gas-filled decade counting tube. Dekatrons were used in computers, calculators and other counting-related products during the 1950s and 1960s. “Dekatron,” now a generic trademark, was the brand name used by the British Ericsson Telephones Limited (ETL), of Beeston, Nottingham (not to be confused with the Swedish TelefonAB Ericsson of Stockholm).

I have several old soviet tubes A106. It is high speed, hydrogen filled dekatron. It is special tube to count or divide impulses. This particular tube is “very soviet”- it is unstable, sometimes misses pulses or jump two segments from one pulse. Maybe this happened because of very simplified circuit I’ve used to test?

Dekatron tube in action
It glowing everywhere because of long exposure when making photo. It was fed by 50Hz mains current and tiny dot run around 5 times in a second. And the color of the tube is absolutely different.

Here is the animation:

And here is the circuit diagram to test the tube. Warning! High voltage abroad. Schematics are very typical- voltage multiplier and pulse shaper. The only problem with hydrogen filled tubes is high working voltage.
dekatron schematics

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2 Responses to Dekatron

  1. please could you tell me what the pin numbers are i:e does pin 4 mean anode ect.also i see you have link out wire joining pins a bit like i have done on an a101 on mains supply or please send a photo of the tube wiring on the underneath .


  2. Sorry, original Lithuanian post is dated 2008. I can not recall pin numbers either find this device in my garage.
    But fast look at google reveals that:
    А106 (А is not A, but russian “А”) 🙂
    1- cathode “0”, 2- “9”, 3-“8”, 4-“7”, 5-subcathode (count), 6- “6”, 7-“5”, 8- anode, 9-“4”, 10-n.c., 11- “3”, 12-“2”, 13-“1”.
    In my circuit, all numbered cathodes are connected, pulse goes to counting pin, anode is anode 🙂

    P.S. my circuit will work if mains voltage is 230V.

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