Resistance controlled timed pulse generator

Claim 2

An electronic switching circuit responsive to a change of resistance in a sensing element, comprising: an insulated gate field effect transistor, having, a gate, a drain, and a source; a source of power having two output terminals; switch means interconnecting one terminal of the source of power and the said transistor drain, a resistive load interconnecting the said transistor source and the other terminal of the source of power; resistive means interconnecting the said gate and the said source; and resistive sensing means interconnecting the said gate and the said other terminal of the source of power.

Claim 3

The combination of claim 1, and further including an integrating amplifier having an output and an input, resistance-capacitance time constant means interconnecting said input to the transistor side of the switch means, alarm actuating means; and means interconnecting the alarm actuating means and the said output of the integrating amplifier.

Claim 4

The combination of claim 2 and further including a second time delay network; means operatively interconnecting the said second time delay network and the switch means whereby the switching period of the switch means is responsive to the second time delay network characteristics.

Claim 5

The combination of claim 3 wherein said switch means comprises at least one solid state transistor device and means interconnecting the emitter-collector circuit of said transistor in series between the said power source and the said field effect transistor.

Claim 6

The combination of claim 4 and further including means interconnecting the output of the integrating amplifier and the switching means whereby said switching means is disabled when an output is present from the said integrating amplifier.

Claim 7

The combination of claim 5 wherein the resistive sensing means is an open ionization chamber having a source of radioactive radiation, an anode and a cathode disposed in spaced apart relation.

Claim 8

The combination of claim 6 wherein the said alarm actuating means is an electromagnetic relay.

Claim 9

An electronic switching circuit responsive to a change of resistance in a sensing element, comprising: an insulated gate field effect transistor, having, a gate, a drain, and a source; a source of power having two output terminals; switch means interconnecting one terminal of the source of power and the said drain; a switching amplifier having an input and an output, said input connected to the source-drain circuit of said field effect transistor and said output connected to the switch means and wherein said switch means is responsive to changes in voltage applied thereto; a resistive load interconnecting the said source and the other terminal of the source of power; resistive means interconnecting the said gate and the said source; and resistive sensing means interconnecting the said gate and the said other terminal of the said source of power wherein the resistive sensing means is an open ionization chamber having a source of radioactive radiation, an anode and a cathode disposed in spaced apart relation.

Claim 10

An electronic switching circuit responsive to a change of resistance in a sensing element, comprising: an insulated gate field effect transistor, having, a gate, a drain, and a source; a source of power having two output terminals; switch means interconnecting one terminal of the source of power and the said drain; a switching amplifier having an input and an output, said input connected to the source-drain circuit of said field effect transistor and said output connected to the switch means and wherein said switch means is responsive to changes in voltage applied thereto; a resistive load interconnecting the said source and the other terminal of the source of power; resistive means interconnecting the said gate and the said source; and resistive sensing means interconnecting the said gate and the said other terminal of the said source of power wherein the resistive sensing means is an open ionization chamber having a source of radioactive radiation, an anode and a cathode disposed in spaced apart relation.

Claim 11

The combination of claim 8, and further including an integrating amplifier having an output and an input, resistance-capacitance time constant means interconnecting said input to the transistor side of the switch means; alarm actuating means; and means interconnecting the alarm actuating means and the said output of the integrating amplifier.

Claim 12

The combination of claim 9 wherein said switch means comprises at least one solid state transistor device and means interconnecting the emitter-collector circuit of said transistor in series between the said power source and the said field effect transistor.