Telemetry-actuated switch

Claim 2

A switch comprising; a first bistable element for providing either a high-impedance or a low-impedance electrical path; means for switching said bistable element from its highimpedance to its low-impedance state in response to a first control pulse; means responsive to both said first control pulse and a second control pulse for short circuiting said bistable element thereby to drive said bistable element from its low-impedance to its high-impedance state; and means for maintaining a surge of current through said bistable element for a selected period when said bistable element is being switched from its high-impedance to its low-impedance state, thereby to hold said bistable element in its lowimpedance state despite the momentary partial short-circuiTing of said bistable element by said means for short circuiting.

Claim 3

Structure as in claim 1 wherein said first bistable element comprises a first silicon-controlled rectifier.

Claim 4

Structure as in claim 2 wherein said means for switching said first bistable element comprises; means for receiving a transmitted signal; means for producing said first control pulse from said transmitted signal; and means for applying said first control pulse to the gate of said first silicon-controlled rectifier thereby to switch said silicon-controlled rectifier from its high-impedance to its low-impedance state.

Claim 5

Structure as in claim 3 where said means for shorting said first bistable element comprises; a second silicon-controlled rectifier responsive to both said first and said second control pulses; at least two impedance elements connected in series with the anode-to-cathode circuit of said second silicon-controlled rectifier to maintain its anode-to-cathode current beneath the minimum holding current necessary to maintain this second silicon-controlled rectifier in its low-impedance state in the absence of said first and second control pulses; and, means responsive to current through the anode-to-cathode circuit of said second silicon-controlled rectifier to partially and momentarily short circuit said first silicon-controlled rectifier.

Claim 6

Structure as in claim 4 where said means responsive to current through the anode-to-cathode circuit of said second silicon-controlled rectifier comprise; a first transistor, the base of which is connected at the node between said at least two impedance elements, the collector of which is connected through a resistor to a power supply, and the emitter of which is connected to the other terminal of said power supply; and a second transistor the base of which is connected to the node between the collector of said first transistor and said resistor, and the emitter and collector of which are connected across the anode-to-cathode circuit of said first silicon-controlled rectifier, said second transistor being driven into saturation by the collector current through said first transistor, thereby to partially short circuit said first silicon-controlled rectifier during the period said second silicon-controlled rectifier conducts current.

Claim 7

Structure as in claim 5 wherein said means for maintaining a surge of current through said first bistable element for a selected period comprises; current storing means connected in series with the anode-to-cathode circuit of said first silicon controlled rectifier and said power supply, said current storage means drawing a large current when said first bistable element is switched from its high-impedance to its low-impedance state, but said current storing means drawing no current when said first bistable element is switched from its low-impedance to its high-impedance state.

Claim 8

Structure as in claim 1 including in addition a selected instrument connected to said power supply by said first bistable element.

Claim 9

Structure as in claim 1 including; a third transistor for interconnecting a power supply and an instrument; and, means responsive to current through said first bistable element for driving said third transistor into its saturated state, thereby to provide through said transistor a low-impedance path between said power supply and said instrument.

Claim 10

A telemetry-actuated switch for connecting a power supply to an instrument, said switch comprising; a first bistable element for providing either a high-impedance or a low-impedance electrical path between said power supply and said instrument; means for switching said bistable element from its high-impedance to its low-impedance state in response to a first control signal; means responsive to both said first control signal and a second control signal for momentarily and partially short-circuiting said bistable element thereby to drive said bistable element from its low-impedancE to its high-impedance state; means for maintaining a surge of current through said bistable element for a selected period when said bistable element is being switched from its high-impedance to its low-impedance state, thereby to hold said bistable element in its low-impedance state despite the momentary partial short-circuiting of said bistable element by said means for short-circuiting; and, means for generating said first and second control signals from first and second transmitted signals.

Claim 11

A telemetry-actuated switch for connecting a power supply to an instrument, said switch comprising; a first bistable element for providing either a high-impedance or a low-impedance electrical path between said power supply and said instrument; means for switching said bistable element from its high-impedance to its low-impedance state in response to a first control signal; means responsive to both said first control signal and a second control signal for momentarily and partially short-circuiting said bistable element thereby to drive said bistable element from its low-impedancE to its high-impedance state; means for maintaining a surge of current through said bistable element for a selected period when said bistable element is being switched from its high-impedance to its low-impedance state, thereby to hold said bistable element in its low-impedance state despite the momentary partial short-circuiting of said bistable element by said means for short-circuiting; and, means for generating said first and second control signals from first and second transmitted signals.

Claim 12

A telemetry-actuated switch for connecting a power supply to an instrument, said switch comprising; a first bistable element for providing either a high-impedance or a low-impedance electrical path between said power supply and said instrument; means for switching said bistable element from its high-impedance to its low-impedance state in response to a first control signal; means responsive to said first control signal for generating a second control signal after a predetermined time from the receipt of said first control signal; means responsive to said second control signal for momentarily short-circuiting said first bistable element thereby to drive said first bistable element from its low-impedance to its high-impedance state.

Claim 13

A telemetry-actuated switch for connecting a power supply to an instrument, said switch comprising; a first bistable element for providing either a high-impedance or a low-impedance electrical path between said power supply and said instrument; means for switching said bistable element from its high-impedance to its low-impedance state in response to a first control signal; means responsive to said first control signal for generating a second control signal after a predetermined time from the receipt of said first control signal; means responsive to said second control signal for momentarily short-circuiting said first bistable element thereby to drive said first bistable element from its low-impedance to its high-impedance state.

Claim 14

Structure as in claim 10 in which said means responsive to said first control signal comprise; a resistor and a capacitor connected in series, with said first bistable element such that when said first bistable element switches from its high to its low-impedance state a current flows through said capacitor thereby to charge said capacitor, a unijunction transistor the emitter of which is connected to the node between said resistor and capacitor, such that when the voltage across said capacitor rises to exceed a selected minimum value, said unijunction transistor is turned from its off to its on state, and a voltage divider network consisting of two resistors, the base of said unijunction transistor being connected to the node between said two resistors.

Claim 15

Structure as in claim 11 in which said means responsive to said second control signal comprises; a first and a second transistor driven into saturation by said second control signal, said first transistor shorting said first bistable element thereby to drive said first bistable element from its low- to its high-impedance state.