Method and apparatus for testing a conductivity sensing circuit

Claim 2

Apparatus for testing a circuit which senses the condition of an electrical quantity, said quantity being electrical conductivity, said sensing circuit having a pair of sensing terminals, a sensor portion operatively connected to said terminals for indicating a predetermined condition of the electrical quantity associated with a load connected between said terminals, and a current conducting component which is activated in response to a predetermined amount of energy supplied thereto after said sensor indicates said condition of said electrical quantity, said component to be activated in response to conductivity greater than a given value, said testing apparatus comprising: (a) a pair of terminals for connection to said sensing circuit terminals; (b) a network connected to said terminals for simulating a load having the electrical quantity to which said sensing circuit is responsive, said network having at least one branch which simulates the existence of said predeteremined condition in said load, said branch including timing means causing said predetermined condition to be simulated for a period of time adequate to test the response of said sensing circuit but inadequate to provide sufficient energy to activate said component, said network branch having an initial low resistance to simulate conductivity greater than said given value and which then is changed in response to said timing means to a high resistance to simulate conductivity lower than said predetermined value thereby enabling testing the electrical continuity of said component in response to conductivity greater than said given value and in a manner preventing activation of said component; and (c) monitoring means connected to said terminals for comparing the actual response of said sensing circuit to the load simulation provided by said network to the desired response of said network.

Claim 3

Apparatus according to claim 1, wherein said network has a second branch which simulates the absence of said predetermined condition in said load.

Claim 4

Apparatus according to claim 2, further including switching means between said network and at least one of said testing apparatus terminals for selecting which of said branches is connected to said terminals.

Claim 5

Apparatus according to claim 1, wherein said sensing circuit includes a battery for supplying voltage to said circuit and wherein said testing apparatus includes circuit means for disconnecting said network from said testing apparatus terminals and for completing a circuit including said sensing circuit battery and said monitoring means for monitoring the operation of said battery.

Claim 6

Apparatus according to claim 1, wherein said monitoring means includes means for indicating whether the actual and desired responses of said sensing circuit are within or without a predetermined range of coincidence.

Claim 7

Apparatus according to claim 1, wherein said monitoring means includes an oscilloscope.

Claim 8

Apparatus according to claim 6, wherein said oscilloscope has a flat screen provided with graphical information to visually indicate whether the actual and desired responses of said sensing circuit are within or without a predetermined range of coincidence.

Claim 9

Apparatus according to claim 1, wherein said monitoring means includes microprocessor means for comparing information from waveforms indicating the actual response of said sensing circuit to information stored in said microprocessor means representing the desired response of said sensing circuit and for indicating whether the actual and desired responses of said sensing circuit are within or without a predetermined range of coincidence.

Claim 10

Apparatus according to claim 1, wherein said current conducting component of said sensing circuit is an electro explosive device which is detonated when electrical energy of said predetermined amount is supplied thereto.

Claim 11

Apparatus according to claim 9, wherein said electro explosive device is included in a release mechanism for uncoupling a parachute canopy from its load upon landing in water, said canopy being uncoupled when said electro explosive device is detonated, and said electro explosive device being detonated when said electrode means is exposed to water having a predetermined condition of conductivity.

Claim 14

A method according to claim 11, wherein each of said steps of applying a load to said sensing circuit comprises applying a resistive load.

Claim 15

A method according to claim 11, wherein said steps of applying a load to said sensing circuit comprises: (a) applying to said sensing circuit terminals a network including two portions connected in parallel, the first of said portions comprising a low magnitude resistor in series with a capacitor and the second of said portions including a relatively higher magnitude resistor; and (b) operating said network in a manner such that initially said sensing circuit responds only to said low magnitude resistor simulating conductivity greater than said given value and then after the voltage increases on said capacitor during said period of time said circuit responds to said higher magnitude resistor simulating conductivity less than said given value.

Claim 16

Apparatus for testing a circuit senses the condition of an electrical quantity, said quantity being electrical conductivity, said sensing circuit having a pair of sensing terminals, a sensor portion operatively connected to said terminals for indicating a predetermined condition of the electrical quantity associated with a load connected between said terminals, and a current conducting component which is activated in response to a predetermined amount of energy supplied thereto after said sensor indicates said condition of said electrical quantity, said component to be activated in response to conductivity greater than a given value, said testing apparatus comprising: (a) a pair of terminals for connection to said sensing circuit terminals; (b) a network connected to said terminals for simulating a load having the electrical quantity to which said sensing circuit is responsive, said network having at least one branch which simulates the existence of said predetermined condition in said load, said branch including timing means causing said predetermined condition to be simulated for a period of time adequate to test the response of said sensing circuit but inadequate to provide sufficient energy to activate said component, said network branch having an initial low resistance to simulate conductivity greater than said given value and which then is changed in response to said timing means to a high resistance to simulate conductivity lower than said predetermined value thereby enabling testing the electrical continuity of said component in response to conductivity greater than said given value and in a manner preventing activation of said components, said network branch including two portions connected in parallel, the first of said portions comprising a low magnitude resistor in series with a capacitor and the second of said portions including a relatively higher magnitude resistor, said network operating in a manner such that initially said sensing circuit responds only to said low magnitude resistor simulating conductivity greater than said given value and then after the voltage increases on said capacitor during said period of time said circuit responds to said higher magnitude resistor simulating conductivity less than said given value; and (c) monitoring means connected to said terminals for comparing the actual response of said sensing circuit to the load simulation provided by said network to the desired response of said network.

Claim 17

Apparatus for testing a circuit senses the condition of an electrical quantity, said quantity being electrical conductivity, said sensing circuit having a pair of sensing terminals, a sensor portion operatively connected to said terminals for indicating a predetermined condition of the electrical quantity associated with a load connected between said terminals, and a current conducting component which is activated in response to a predetermined amount of energy supplied thereto after said sensor indicates said condition of said electrical quantity, said component to be activated in response to conductivity greater than a given value, said testing apparatus comprising: (a) a pair of terminals for connection to said sensing circuit terminals; (b) a network connected to said terminals for simulating a load having the electrical quantity to which said sensing circuit is responsive, said network having at least one branch which simulates the existence of said predetermined condition in said load, said branch including timing means causing said predetermined condition to be simulated for a period of time adequate to test the response of said sensing circuit but inadequate to provide sufficient energy to activate said component, said network branch having an initial low resistance to simulate conductivity greater than said given value and which then is changed in response to said timing means to a high resistance to simulate conductivity lower than said predetermined value thereby enabling testing the electrical continuity of said component in response to conductivity greater than said given value and in a manner preventing activation of said components, said network branch including two portions connected in parallel, the first of said portions comprising a low magnitude resistor in series with a capacitor and the second of said portions including a relatively higher magnitude resistor, said network operating in a manner such that initially said sensing circuit responds only to said low magnitude resistor simulating conductivity greater than said given value and then after the voltage increases on said capacitor during said period of time said circuit responds to said higher magnitude resistor simulating conductivity less than said given value; and (c) monitoring means connected to said terminals for comparing the actual response of said sensing circuit to the load simulation provided by said network to the desired response of said network.