Browse Prior Art Database

Glitch Free Pulse Generation and Contact Closure Detection

IP.com Disclosure Number: IPCOM000086208D
Original Publication Date: 1976-Aug-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Hubbard, JH: AUTHOR [+3]

Abstract

A power line signal is useful in apparatus employing contact closures for timing the machine, not shown, as well as providing a convenient time-out usable in connection with detecting valid contact closures. Two zero-crossover indicating signals ZA and AB are generated, respectively, for indicating the odd numbered and even numbered zero-crossovers. These time displaced signals eliminate races between control latches and relays for providing a solid power base timing control.

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Glitch Free Pulse Generation and Contact Closure Detection

A power line signal is useful in apparatus employing contact closures for timing the machine, not shown, as well as providing a convenient time-out usable in connection with detecting valid contact closures. Two zero-crossover indicating signals ZA and AB are generated, respectively, for indicating the odd numbered and even numbered zero-crossovers. These time displaced signals eliminate races between control latches and relays for providing a solid power base timing control.

A zero-crossover detector provides a zero-crossover indicating signal ZX to a set of synchronizing and sliver-eliminating latches L1-L4, which are timed by a high frequency set of timing pulses C1, C2 to produce the two zero-crossing indicating pulses ZA and ZB. Inspection of the drawing, including the timing diagram, will show operation of latches L1-L4 and the indicated logical interconnections. The leading edge of ZA, ZB are, respectively, in substantial time coincidence with the leading edge of the zero-crossover signal ZX.

A typical application of ZA and ZB is to detect contact closures. A contact can be closed and subjected to bounce. It is desired to use the contact closure only after the bounce has subsided. Such contact can be either manual switches or relay contacts.

Upon closure of the contact, its signal is supplied to a first latch LA, which in turn, operates second latch LB, under the timing control of ZA and ZB to prod...