Instrument for measuring threshold voltage of a semiconductor explosive initiator

Claim 2

An instrument for nondestructive measurement of the firing threshold voltage of a semiconductor type of electroexplosive initiator, comprising a Wheatstone bridge comprising as its four arms (1) said initiator, (2) a first standard resistor, (3) a second standard resistor equal in value to said first standard resistor and a third standard resistor of higher value and bearing a predetermined ratio to said second standard resistor, only one of said second and third standard resistors being in the circuit at a time, and (4) a master potentiometer, means for adjusting said master potentiometer for balancing said bridge to the resistance value of said initiator with said second standard resistor in the bridge, means for substituting said third standard resistor for said second standard resistor in said bridge, means for increasing the voltage through said initiator to a value well short of the firing threshold voltage thereof but sufficient to rebalance the bridge with said third standard resistor therein and means calibrated for the relationship between this actual voltage and the threshold voltage for indicating the voltage drop through said initiator when said third standard resistor is in the bridge in terms of said threshold voltage.

Claim 3

An instrument for nondestructive measurement of parameters of a semiconductor type of electroexplosive initiator, comprising a Wheatstone bridge having four juncture points, with a bridge potentiometer between the first and second juncture points, a first standard resistor between the second and third juncture points, a second standard resistor equal in value to said first standard resistor and a third standard resistor of larger value, one only of said second and third resistors being placed in said bridge at one time and then between the third and fourth juncture points, and a said initiator between said fourth and first junctuRe points, said first juncture point being grounded, a servo amplifier connected to said third juncture points and driven to seek balance in said bridge, a first motor drivable by said servo amplifier and connected to said bridge potentiometer to drive said bridge potentiometer toward balance of said bridge when driven by said servo amplifier, a position indicator for said first motor indicating the value of the bridge resistance of said bridge potentiometer, a direct-current power supply connected on one side to said second juncture point and connectable on the other side to said fourth juncture point through a second potentiometer, a second motor drivable by said servo amplifier for driving said second potentiometer toward balance of said bridge when driven by said servo amplifier and drivable by said power supply for driving said second potentiometer toward a predetermined low resistance value when driven by said power supply, limit means for stopping said motor and said second potentiometer when said predetermined lower value is reached, means for indicating the voltage through said initiator and switch means for connecting in a first ''''on'''' position said second motor to said power supply, for connecting in a second ''''on'''' position said second standard resistor into said bridge and said servo amplifier to said first motor, and for connecting in a third ''''on'''' position said third standard resistor into said bridge and said servo amplifier to said second motor.

Claim 4

An instrument for nondestructive measurement of parameters of a semiconductor type of electroexplosive initiator, comprising a Wheatstone bridge having four juncture points, with a bridge potentiometer between the first and second juncture points, a first standard resistor between the second and third juncture points, a second standard resistor equal in value to said first standard resistor and a third standard resistor of larger value, one only of said second and third resistors being placed in said bridge at one time and then between the third and fourth juncture points, and a said initiator between said fourth and first junctuRe points, said first juncture point being grounded, a servo amplifier connected to said third juncture points and driven to seek balance in said bridge, a first motor drivable by said servo amplifier and connected to said bridge potentiometer to drive said bridge potentiometer toward balance of said bridge when driven by said servo amplifier, a position indicator for said first motor indicating the value of the bridge resistance of said bridge potentiometer, a direct-current power supply connected on one side to said second juncture point and connectable on the other side to said fourth juncture point through a second potentiometer, a second motor drivable by said servo amplifier for driving said second potentiometer toward balance of said bridge when driven by said servo amplifier and drivable by said power supply for driving said second potentiometer toward a predetermined low resistance value when driven by said power supply, limit means for stopping said motor and said second potentiometer when said predetermined lower value is reached, means for indicating the voltage through said initiator and switch means for connecting in a first ''''on'''' position said second motor to said power supply, for connecting in a second ''''on'''' position said second standard resistor into said bridge and said servo amplifier to said first motor, and for connecting in a third ''''on'''' position said third standard resistor into said bridge and said servo amplifier to said second motor.