US3679970A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Selection matrix including a diode test circuit
Assignee: Automatic Electric Laboratories Inc
•
Filing: 1970-04-22
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Granted: 1972-07-25
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Expires: 1990-04-22
Abstract
Abstract A test circuit routinely tests buffer diodes of a selection matrix for shorts. Drive lines that are connected to operating conductors of the selection matrix pass through a toroidal magnetic core to induce into a output winding of the core a voltage proportional to change in current in a selected operating conductor. Switching circuits for applying current to selected conductors are arranged to reverse the polarity of voltage applied to the conductors so that when an operating conductor with a shorted diode is selected, approximately twice the normal current change is detected by the test circuit.
Inventors
- 👤 Hilary M Winters
- 👤 James R Creasy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:06
CPC Classifications
G; G11; G11C; G11C29/00; G11C29/04; G11C29/50; G01; G01R; G01R31/00; G01R31/28; G01R31/30
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
250 words
A selection matrix including a routine test circuit, a plurality of operating conductors, a source of positive potential, a source of direct current, a plurality of isolating diodes one connected in each of said plurality of operating conductors, a plurality of switching means for normally coupling the anode of each of said plurality of isolating diodes to ground potential and the cathode of each of said isolating diodes to said source of positive potential thereby reverse biasing said isolating diodes, said diodes normally being operative to prevent electrical current flow in said operating conductors during the normal state of said switching means, said switching means in an operated state effectively reversing the polarity with which a selected isolating diode and its associated operating conductor is coupled to said source of positive potential to thereby produce a direct current in said conductor in the forward direction, a single magnetic core inductively coupled to all of said plurality of operating conductors intermediate said isolating diode anodes and said switching means, an output winding disposed on said magnetic core, a threshold sensing circuit coupled to said output winding and operative to produce an output only in response to an electrical current change in excess of a selected level, whereby a shorted isolating diode permits reversal of current flow in its associated operating conductor when said switching means is returned to said normal state from said operated state, said current flow reversal being sufficient to stimulate an output from said threshold sensing circuit. switching
Claim 2
Dependent Claim
250 words
A selection matrix including a routine test circuit, a plurality of operating conductors, a source of positive potential, a source of direct current, a plurality of isolating diodes one connected in each of said plurality of operating conductors, a plurality of switching means for normally coupling the anode of each of said plurality of isolating diodes to ground potential and the cathode of each of said isolating diodes to said source of positive potential thereby reverse biasing said isolating diodes, said diodes normally being operative to prevent electrical current flow in said operating conductors during the normal state of said switching means, said switching means in an operated state effectively reversing the polarity with which a selected isolating diode and its associated operating conductor is coupled to said source of positive potential to thereby produce a direct current in said conductor in the forward direction, a single magnetic core inductively coupled to all of said plurality of operating conductors intermediate said isolating diode anodes and said switching means, an output winding disposed on said magnetic core, a threshold sensing circuit coupled to said output winding and operative to produce an output only in response to an electrical current change in excess of a selected level, whereby a shorted isolating diode permits reversal of current flow in its associated operating conductor when said switching means is returned to said normal state from said operated state, said current flow reversal being sufficient to stimulate an output from said threshold sensing circuit. switching
Claim 3
Dependent Claim
215 words
A selection matrix as recited in claim 1 wherein each of said plurality of switching means comprises a transistor driver having a collector coupled in parallel with said source of positive potential and the anode of said isolating diodes, an emitter coupled to ground potential and a base coupled to the positive polarity side of said direct current source and a switching transistor having a collector coupled in parallel with said source of positive potential and the cathode of said isolating diodes, an emitter coupled to ground potential and a base coupled to the negative polarity side of said direct current source; the emitter-collector circuit of said transistor drivers being normally conductive to thereby normally couple the diode anode end of said operating conductors to ground potential, and the emitter-collector circuit of said switching transistors being normally non-conductive to thereby normally couple the diode cathode end of said operating conductors to said source of positive potential; and the emitter-collector circuit of said transistor drivers being non-conductive in said operated state to thereby couple the diode anode end of said selected line to said source of positive potential, and the emitter-collector circuit of said switching transistors being conductive in said operated state to thereby couple the diode cathode end of said selected line to ground potential.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |