Counter tube
A counter tube , also called a Dekatron (because it can usually count a decade ), is a special electron tube filled with gas that can count with the help of glow discharges and their negative differential internal resistance . In contrast, the trochotron is a vacuum tube that counts by deflecting an electron beam (i.e. it is a type of cathode ray tube ). Counting tubes are no longer used today.
The counter tube is not to be confused with indicator tubes for displaying symbols such as numbers or letters.
Counting tubes with glow discharge
As a rule, ten glow and display cathodes are housed in the tube , which, separated from one another by insulating fittings, but fed together, face an anode . When a trigger pulse is generated at an auxiliary electrode, a glow discharge alternates between the cathodes. The discharge jumps from one cathode to the next.
The interior structure is designed so that
- only one cathode is lit at a time
- the discharge changes in the specified sequence when triggered. One example is the ZM 1070, it can count with up to 5 kHz.
Some of these tubes also require an additional external flip-flop .
Cathode ray counting tubes
These tubes also display, but a fluorescent lamp is required. One example is the E1T type , which can count to ten. The maximum counting frequency is 30 kHz.
The 6710 can count quickly up to 10 kHz (under suitable conditions up to 2 MHz). It requires an upstream flip-flop.
commitment
Such counter tubes were used, among other things, in early computers ( Harwell Dekatron ), counters , short-term meters and - together with counter tubes - to display the number of events in radioactivity measuring devices.
Several tubes could be interconnected to form multi-digit meters. Some can count both ways.
Individual references and web links
- Explanations of decatrons with pictures of different types
- Detailed description of a Geiger counter built at the TU Berlin with decadic counter tubes E1T
- ↑ http://www.jogis-roehrenbude.de/Roehren-Geschichtliches/Nixie/ZM1070/ZM1070.pdf data sheet ZM1070
- ↑ http://www.jogis-roehrenbude.de/Roehren-Geschichtliches/Nixie/E1T.htm on counting tubes
- ↑ http://frank.pocnet.net/sheets/009/e/E1T.pdf data sheet E1T
- ↑ http://frank.pocnet.net/sheets/116/6/6710.pdf data sheet 6710