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Capacitor-Coupled, Neon-Photoconductor Flip-Flop

IP.com Disclosure Number: IPCOM000097972D
Original Publication Date: 1961-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Corradetti, M: AUTHOR

Abstract

Coupling with a single capacitor provides positive switching in a two neon flip flop with no switch-off delay. The flip flop neons A and B are capacitively coupled by capacitor C between their current limiting resistors 10 and 12 at points 14 and 16. A and B are each self latching through the respective latching photoconductors A1 and B1. A is turned on by a SET lamp having a photoconductor connected in parallel with A1. B is turned on by a RESET lamp having a photoconductor in parallel with B1.

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Capacitor-Coupled, Neon-Photoconductor Flip-Flop

Coupling with a single capacitor provides positive switching in a two neon flip flop with no switch-off delay. The flip flop neons A and B are capacitively coupled by capacitor C between their current limiting resistors 10 and 12 at points 14 and 16. A and B are each self latching through the respective latching photoconductors A1 and B1. A is turned on by a SET lamp having a photoconductor connected in parallel with A1. B is turned on by a RESET lamp having a photoconductor in parallel with B1.

When A is on, the potential level at 14 is reduced causing C to charge, with the voltage at 16 substantially higher than the voltage at 14. If B is then turned on by operation of the RESET lamp, the potential level at 16 is immediately reduced and the capacitive coupling causes a resultant transient depression of the voltage at 14 which extinguishes A immediately. As C then charges in the opposite sense, the photoconductivity of A1 decays so that the combination of potential at 14 and conductivity at A1 is never sufficient to re ignite A. Reverse operation from B to A follows the same principles.

Thus, this flip flop is fast because the extinguishing of the neon, which is switched off, is not delayed by the slow photoconductivity decay time. The switching of other neon photoconductor circuits often depends upon the decay of current in a photoconductor.

If A and B are erroneously switched on together, a circuit path is forme...