Timer employing current drain characteristic of battery

Claim 2

A timer for providing a time delay interval, comprising: a battery having a pair of terminals and a terminal voltage versus time characteristic established in terms of rate of current drain from saiD battery as a function of time; resistive means connected in circuit with said battery for providing a desired rate of current drain from said battery; actuable means having at least two operative states and responsive to attainment of a predetermined battery terminal voltage in the course of said current drain for assuming one of said two operative states, said predetermined battery terminal voltage being less by a predetermined increment than the rated terminal voltage for said battery prior to said current drain; means for initiating said time delay interval by connecting said terminals to said resistive means in such relation that said resistive means drains current from said battery; Wherein said actuable means includes a relay circuit comprising a relay coil responsive to the voltage between said pair of terminals and further comprising a pair of normally closed relay contacts, said relay coil being arranged and adapted to maintain said contacts open only while the terminal voltage of said battery is above said predetermined voltage; wherein said resistive means further comprises a nonlinear resistance element connected in series with said relay coil and said battery, said element having a greater resistance when low voltages are applied thereacross than when high voltages are applied thereacross, whereby the voltage across said relay coils decreases in accordance with the cumulative effects of decreasing battery terminal voltage and increasing resistance of said element; and wherein said relay circuit includes a second relay coil connected in parallel with a the series combination of said first-mentioned relay coil and said nonlinear resistance element, said second relay coil being arranged to provide an opposing and smaller magnetomotive force than that provided by said first-mentioned relay coil when both coils conduct equal currents, whereby the magnetomotive forces provided by said relay coils are substantially equal and opposite upon attainment of said predetermined terminal voltage at said battery.

Claim 3

A timer for providing a time delay interval, comprising: a battery having a pair of terminals and a terminal voltage versus time characteristic established in terms of rate of current drain from said battery as a function of time; resistive means connected in circuit with said battery for providing a desired rate of current drain from said battery; actuable means having at least two operative states and responsive to attainment of a predetermined battery terminal voltage in the course of said current drain for assuming one of said two operative states, said predetermined battery terminal voltage being less by a predetermined increment than the rated terminal voltage for said battery prior to said current drain; means for initiating said time delay interval by connecting said terminals to said resistive means in such relation that said resistive means drains current from said battery; wherein said actuable means includes a relay circuit comprising a relay coil responsive to the voltage between said pair of terminals and further comprising a pair of normally closed relay contacts, said relay coil being arranged and adapted to maintain said contacts open only while the terminal voltage of said battery is above said predetermined voltage; and further comprising a load device for effecting a specified operation upon conduction of current therethrough, means for connecting said load device in series with said pair of normally closed relay contacts, capacitor means connected in parallel with the series combination of said load device and said pair of normally closed relay contacts for transiently providing a short circuit across said series combination upon initiation of said time delay interval, and a timing circuit for slowly charging said capacitor from said battery, whereby said load device is prevented from conducting current until said capacitor is sufficiently charged and said battery attains said prEdetermined terminal voltage.

Claim 4

A timer for providing a time delay interval, comprising: a battery having a pair of terminals and a terminal voltage versus time characteristic established in terms of rate of current drain from said battery as a function of time; resistive means connected in circuit with said battery for providing a desired rate of current drain from said battery; actuable means having at least two operative states and responsive to attainment of a predetermined battery terminal voltage in the course of said current drain for assuming one of said two operative states, said predetermined battery terminal voltage being less by a predetermined increment than the rated terminal voltage for said battery prior to said current drain; means for initiating said time delay interval by connecting said terminals to said resistive means in such relation that said resistive means drains current from said battery; wherein said actuable means includes a relay circuit comprising a relay coil responsive to the voltage between said pair of terminals and further comprising a pair of normally closed relay contacts, said relay coil being arranged and adapted to maintain said contacts open only while the terminal voltage of said battery is above said predetermined voltage; and further comprising a load device for effecting a specified operation upon conduction of current therethrough, means for connecting said load device in series with said pair of normally closed relay contacts, capacitor means connected in parallel with the series combination of said load device and said pair of normally closed relay contacts for transiently providing a short circuit across said series combination upon initiation of said time delay interval, and a timing circuit for slowly charging said capacitor from said battery, whereby said load device is prevented from conducting current until said capacitor is sufficiently charged and said battery attains said prEdetermined terminal voltage.

Claim 5

The timer according to claim 2 wherein said timing circuit is connected in series with said capacitor and wherein the series combination of the timing circuit and the capacitor is connected in parallel with said relay coil, said timing circuit comprising a diode and a resistor connected in series, said diode being poled to conduct current from said battery.

Claim 6

A timer for providing a time delay interval comprising: a battery having a pair of terminals and a terminal voltage versus time characteristic established in terms of rate of current drain from said battery as a function of time; resistive means connected in circuit with said battery for providing a desired rate of current drain from said battery; actuable means having at least two operative states and responsive to attainment of a predetermined battery terminal voltage in the course of said current drain for assuming one of said two operative states, said predetermined battery terminal voltage being less by a predetermined battery terminal voltage being less by a predetermined increment than the rated terminal voltage for said battery prior to said current drain; means for initiating said time delay interval by connecting said terminals to said resistive means in such relation that said resistive means drains current from said battery; wherein said actuable means comprising a transistor having base, collector and emitter electrodes, and means for biasing said transistor in a nonconducting condition for battery voltages above said predetermined terminal voltage and in conducting condition for battery voltages equal to and less than said predetermined terminal voltage; further comprising a load device connected in series of with the collector-emitter circuit of said transistor, said load device being responsive to current flow therethrough for effecting a specified operation; wherein said means for biasing said transistor comprises: a source of reference potential; a further battery; means for connecting said further battery in series aiding relating with said first mentioned battery; a voltage divider network; means for connecting said voltage divider network in closed series circuit with said series-connected batteries; means for connecting said base electrode to a first circuit point intermediate said voltage divider network; said circuit point being at a potential which is less than said reference potential when said first-mentioned battery is at its rated terminal voltage prior to said drain; means for connecting the series combination of said load device and the collector-emitter circuit of said transistor in shunt with said further battery; and means for connecting said source of reference potential to a second circuit point intermediate said series-connected batteries.

Claim 7

A timer for providing a time delay interval comprising: a battery having a pair of terminals and a terminal voltage versus time characteristic established in terms of rate of current drain from said battery as a function of time; resistive means connected in circuit with said battery for providing a desired rate of current drain from said battery; actuable means having at least two operative states and responsive to attainment of a predetermined battery terminal voltage in the course of said current drain for assuming one of said two operative states, said predetermined battery terminal voltage being less by a predetermined battery terminal voltage being less by a predetermined increment than the rated terminal voltage for said battery prior to said current drain; means for initiating said time delay interval by connecting said terminals to said resistive means in such relation that said resistive means drains current from said battery; wherein said actuable means comprising a transistor having base, collector and emitter electrodes, and means for biasing said transistor in a nonconducting condition for battery voltages above said predetermined terminal voltage and in conducting condition for battery voltages equal to and less than said predetermined terminal voltage; further comprising a load device connected in series of with the collector-emitter circuit of said transistor, said load device being responsive to current flow therethrough for effecting a specified operation; wherein said means for biasing said transistor comprises: a source of reference potential; a further battery; means for connecting said further battery in series aiding relating with said first mentioned battery; a voltage divider network; means for connecting said voltage divider network in closed series circuit with said series-connected batteries; means for connecting said base electrode to a first circuit point intermediate said voltage divider network; said circuit point being at a potential which is less than said reference potential when said first-mentioned battery is at its rated terminal voltage prior to said drain; means for connecting the series combination of said load device and the collector-emitter circuit of said transistor in shunt with said further battery; and means for connecting said source of reference potential to a second circuit point intermediate said series-connected batteries.