Glow discharge indicator tube for small signals

A new glow discharge indicator tube was developed for the purpose of obtaining a visible indication of the small-signal voltage obtained from transistors or other small-signal sources. The principle of operation is based upon the current transfer between two adjacent cathodes. In this indicator tube about 60 Mw (200 v 300µa) of power dissipation is required to keep the glow on the sustaining cathode, and only a few volts of negative potential are required to transfer the glow to the indicator cathode. In addition to its ability to indicate very small signals, this tube has several other outstanding features. These are 1) small size, 2) small power dissipation, 3) stable characteristics, and 4) long life compared with other types of indicators (e.g., a lamp or a gas-filled tube indicator). This paper describes in detail the principle of operation, construction, electrical characteristics and applications of a new type of indicator for small signals.