Squib control circuit

Claim 2

A circuit for feeding a relative relatively high power current pulse to a load comprising: a low peak power source of a DC voltage having a pair of output terminals across which the DC voltage appears, a capacitor, a resistor, means connecting said capacitor and resistor in series between said output terminals of said source of DC voltage, so the capacitor charges to said DC voltage through the resistor, load means through which a current pulse is to be fed, self-resetting threshold switch means connected in series with said load means across said capacitor, said threshold switch means normally presenting a high resistance current blocking condition for substantially blocking current through said load means and wherein said high resistance in response to a voltage applied across said threshold switch means above a given threshold voltage value greater than said DC voltage substantially instantaneously decreases to a low resistance conducting condition which low resistance conducting condition persists until the current flowing therethrough drops below a given holding current level, and a relatively low power voltage pulse source for triggering said threshold switch device from said high resistance blocking condition to said low resistance conducting condition, said capacitor then discharging to feed a high power current pulse through said load means, said load means being one which remains intact when said capacitor discharges therethrough and said resistor being of a value to reduce the current flow through said threshold switch means to a value below said holding current level after said capacitor has discharged.

Claim 3

A circuit for feeding a relatively high power current pulse to a load comprising: a low peak power source of DC voltage having a pair of output terminals across which the DC voltage appears, a capacitor, a resistor, means connecting said capacitor and resistor in series between said output terminals of said source of DC voltage, so the capacitor charges to said DC voltage through the resistor, a squib element through which a current pulse is to be fed to heat and blow the said self-resetting threshold switch means connected in series with said load means across said capacitor, said threshold switch means normally presenting a high resistance current blocking condition for substantially blocking current through said load means and wherein said high resistance in response to a voltage applied across said threshold switch means above a given threshold voltage value greater than said DC voltage substantially instantaneously decreases to a low resistance conducting condition persists which low resistanCe conducting condition persists until the current flowing therethrough drops below a given holding current level, a relatively low power voltage pulse source for triggering said threshold switch device from said high resistance blocking condition to said low resistance conducting condition, said capacitor then discharging to feed a high power current pulse through said load means, and a test circuit for testing the operation of said threshold switch means, said test circuit comprising a test fuse which will blow if substituted for said squib element, and manually operable switch means for selectively connecting said squib or fuse element in series with said threshold switch means.

Claim 4

A circuit for feeding a relatively high power current pulse to a load comprising: a low peak power source of DC voltage having a pair of output terminals across which the DC voltage appears, a capacitor, a resistor, means connecting said capacitor and resistor in series between said output terminals of said source of DC voltage, so the capacitor charges to said DC voltage through the resistor, a squib element through which a current pulse is to be fed to heat and blow the said self-resetting threshold switch means connected in series with said load means across said capacitor, said threshold switch means normally presenting a high resistance current blocking condition for substantially blocking current through said load means and wherein said high resistance in response to a voltage applied across said threshold switch means above a given threshold voltage value greater than said DC voltage substantially instantaneously decreases to a low resistance conducting condition persists which low resistanCe conducting condition persists until the current flowing therethrough drops below a given holding current level, a relatively low power voltage pulse source for triggering said threshold switch device from said high resistance blocking condition to said low resistance conducting condition, said capacitor then discharging to feed a high power current pulse through said load means, and a test circuit for testing the operation of said threshold switch means, said test circuit comprising a test fuse which will blow if substituted for said squib element, and manually operable switch means for selectively connecting said squib or fuse element in series with said threshold switch means.