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Bounce Eliminating Circuit

IP.com Disclosure Number: IPCOM000075305D
Original Publication Date: 1971-Aug-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Klose, U: AUTHOR

Abstract

This circuit ensures a reliable set-reset operation for a silicon controlled sectifier (SCR) stage, which is biased through a mechanical switch.

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Bounce Eliminating Circuit

This circuit ensures a reliable set-reset operation for a silicon controlled sectifier (SCR) stage, which is biased through a mechanical switch.

A capacitor C1, having a long-charge time, is charged from line inputs L1, L2 through resistors R5 and %4. When a mechanical switch S1, for instance a relay contact, is closed the SCR T1 obtains a bias from L1, R5, S1, a resistor R3 and a diode D1. This bias sets T1 from L1 through a resistor R6 and a diode D3, and an output is provided on A. When T1 is set the capacitor C1 discharges over diode D2 and T1.

When the polarity on L1 and L2 changes, T1 will be cut-off. A second polarity change on L1 and L2 will not set T1 since the resistance value for R5 is large compared to R3 and the two resistors R1 and R2 connected between D1 and L2.

T1 will remain cutoff until Sl remains open for a time period long enough to permit C1 to charge up to a reasonably high value. Thus, a short-time duration bounce on S1 will not produce an erroneous setting of T1.

A reset signal applied to point B resets T1 via a capacitor C2, if T1 is in the on state.

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