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Timing Circuit

IP.com Disclosure Number: IPCOM000096670D
Original Publication Date: 1963-Sep-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Delanoy, RL: AUTHOR [+4]

Abstract

The timer is used in telegraph communication systems in which terminal lockout is effected when the terminal is idle for a predetermined time duration, e.g., 15 seconds. This timer achieves a high degree of accuracy in establishing the lockout period and a high timing to recovery ratio, e.g,, in excess of 400 to 1.

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Timing Circuit

The timer is used in telegraph communication systems in which terminal lockout is effected when the terminal is idle for a predetermined time duration, e.g., 15 seconds.

This timer achieves a high degree of accuracy in establishing the lockout period and a high timing to recovery ratio, e.g,, in excess of 400 to 1.

The timer has a multivibrator 1, a capacitor storage circuit 2 which responds to positive-going output pulses from 1 to set a bistable circuit 3 to its lockout condition. This occurs on the first output pulse from 1 after the expiration of the timing period. A capacitor dump circuit 4 responds to a positive voltage level to permit the operation of the timer. Circuit 4 responds to negative pulses, coincident with the transmission of each data pulse, to reset the timer to its initial start condition.

The period of the multivibrator is set by resistor R1, e.g., at 2.5 seconds. Resistors R2 and R3 and capacitor C1 assure a large amplitude positive voltage swing above the ground reference level to overcome the forward bias drops of the diodes D1 and D2 to effect switching the transistor T3 off. Resistor R4 provides an improved rise time at the collector of transistor T2. Capacitors C2 and C3 form a capacitive voltage divider with C2 acting as a coupling element and C3 as the storage element. The number of pulses from 1 to effect the establishment of ground potential on the lower place of T3, so that the next positive pulse is applied to T3 by...