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Glow Tube Driver Circuit

IP.com Disclosure Number: IPCOM000095153D
Original Publication Date: 1965-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Bruce, G: AUTHOR [+3]

Abstract

The circuit selects and repetitively pulses a plurality of glow tubes. Each of these displays one digit of a number described by the glow of a cathode of each cold cathode tube. Although only a single potential source is used, this potential is tripled by an arrangement of capacitors and transistors. The repetitive, high-potential selection provides excellent display from the tubes.

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Glow Tube Driver Circuit

The circuit selects and repetitively pulses a plurality of glow tubes. Each of these displays one digit of a number described by the glow of a cathode of each cold cathode tube. Although only a single potential source is used, this potential is tripled by an arrangement of capacitors and transistors. The repetitive, high- potential selection provides excellent display from the tubes.

In the drawing, circuit elements which function in equivalent manner to other circuit elements are all given the same designation. The following is applicable to any circuit element in accordance with which digit and tube is displayed.

When none of the select inputs is activated, transistor T2 is biased on and transistor T3 is biased off. Capacitors C1 and C2 are then charged to +V. At this time T1 has +V at both its base and emitter and therefore does not conduct. During selection, reversal of bias is applied to both a tube select input and a digit select input each corresponding to the tube and digit which is to be activated. C1 and C2 then tend to discharge across the tube. Additionally, T1 is biased to conduction by a path found through C1. Thus, 3V is applied across the plate and cathode selected.

During an apparently continuous display, the inputs are pulsed a number of times. Between input pulses, C1 and C2 are recharged as described. The repetitive pulsing is effective to maintain the intensity of the glow.

A plurality of such tubes can be selected by...