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885 tube
R.C.A. brand 885 Triode Thyratron
Classification:	Triode Thyratron
Service:	Latching Relay Driver, Relaxation Oscillator, Counter
Cathode
Cathode type:	Indirectly heated
Heater voltage:	6.3
Anode
Max dissipation Watts:
Socket Connections
American 5 Pin Base, (UX5) Pin 1, Heater Pin 2, Anode/Plate Pin-3, Grid Pin-4, Cathode Pin-5, Heater
Reference

The 885 is a small thyratron tube, also known as a gas-filled relay or gas-filled valve. The gas used is xenon. Because of the gas fill thyratrons can handle much greater currents than similar hard vacuum valves/tubes, because the positive ions carry considerable current.

[edit] Uses

This device was used extensively in the timebase circuits of early oscilloscopes in the 1930s. It was employed in a circuit called a relaxation oscillator. During World War II small thyratrons, similar to the 885 were utilized in pairs to construct bistables, the "memory" cells used early computers and code breaking machines. Thyratrons were also used for phase angle control of alternating current (AC) power sources in battery chargers and light dimmers, but these were usually of a larger current handling capacity than the 885. The contemporary electrical equivalent of the 885 is the Silicon Controlled Rectifier (SCR). The 885 is electrically identical to the 884/6Q5, which uses an octal base.

[edit] References

• Radio and Electronic Laboratory Handbook, M.G. Scroggie 1971, ISBN 0-592-05950-2