Auto alarm system

Claim 2

In an alarm system for a motor vehicle, a source of electrical power having a positive terminal and a negative terminal; an alarm device connected to one terminal of said source of power; a switching means connected in series with the alarm device and to the other terminal of the source of power, said switching means being adapted to conduct when current is supplied thereto; and a monostable circuit connected between the positive and negative terminals of the source of power adapted to sense a change in voltage across the source of power and to cause a flow of current to energize the switching means to close same when there is a change in the output of the source of power; said monostable circuit comprising, first and second transistors connected in a common emitter configuration; at least one capacitor in a line connecting the collector of the second transistor to the base of the first transistor; a first resistor in a line between the positive terminal of the source of power and a node on one side of the capacitor; and a second resistor in a line between the positive terminal and a node on the other side of the capacitor wherein the duration of the monostable output signal is determined by the time required to charge the capacitor.

Claim 3

The combination called for in claim 1 with the addition of means to prevent triggering the monostable circuit by a change in the output of the source of power of a duration shorter than a predetermined time.

Claim 4

The combination called for in claim 1 with the addition of rectifier means to protect components of the circuit against reverse connection to the source of power.

Claim 5

In an alarm system for a motor vehicle, a battery; a circuit connected to opposite poles of the battery including a monostable oscillator for providing an output signal when the voltage across the battery is changed, said monostable comprising a first transistor, the base thereof being connected through a resistor to the positive terminal of the battery; a second transistor, the base of which is connected to the collector of the first transistor and through a first capacitor to the negative terminal of the battery; and a second capacitor in a branch connecting the base of the first transistor with the collector of the second transistor in a common emitter circuit, wherein the first transistor is biased on and the second transistor to is biased off during the static condition while the first transistor is biased off during the operating condition and the monostable is in the operating condition for a period of time dependent upon the time constant of the RC circuit; an external trigger circuit connected to the base of the second transistor for triggering the monostable when current is supplied thereto; an amplifier in the circuit to increase the magnitude of the output signal; an alarm device connected to one terminal of the battery on the vehicle; and current responsive switching means connected to the alarm and the other terminal of the battery in the circuit with the alarm, the switching means being triggered by the output signal thereby delivering current to the alarm to Actuate the alarm.

Claim 6

In an alarm system for a motor vehicle, a battery; a circuit connected to opposite poles of the battery including a monostable oscillator for providing an output signal when the voltage across the battery is changed, said monostable comprising a first transistor, the base thereof being connected through a resistor to the positive terminal of the battery; a second transistor, the base of which is connected to the collector of the first transistor and through a first capacitor to the negative terminal of the battery; and a second capacitor in a branch connecting the base of the first transistor with the collector of the second transistor in a common emitter circuit, wherein the first transistor is biased on and the second transistor to is biased off during the static condition while the first transistor is biased off during the operating condition and the monostable is in the operating condition for a period of time dependent upon the time constant of the RC circuit; an external trigger circuit connected to the base of the second transistor for triggering the monostable when current is supplied thereto; an amplifier in the circuit to increase the magnitude of the output signal; an alarm device connected to one terminal of the battery on the vehicle; and current responsive switching means connected to the alarm and the other terminal of the battery in the circuit with the alarm, the switching means being triggered by the output signal thereby delivering current to the alarm to Actuate the alarm.

Claim 7

The combination called for in claim 4 with the addition of a rectifier between the base of the second transistor and the collector of the first transistor to block positive pulses to the collector of the first transistor.

Claim 8

The combination called for in claim 5 wherein the said first capacitor has sufficient capacitance to prevent triggering of the second transistor by a pulse of a duration shorter than a set time.

Claim 9

The combination called for in claim 1 with the addition of an amplifier connected to the monostable adapted to increasing the magnitude of the signal to energize the switching means.

Claim 10

The combination called for in claim 7 wherein the amplifier is a plurality of RC-coupled transistors providing high current gain and phase inversion.

Claim 11

The combination called for in claim 1 with the addition of at least one external trigger circuit comprising at least one second switching means one side thereof being connected to the positive terminal of the source of power, the other side being connected to the base of the second transistor in the monostable whereby closing the second switching means triggers the monostable to route a signal to the first switching means, the second switching means being positionable in a concealed location on the motor vehicle.

Claim 12

The combination called for in claim 9 wherein the switching means is adapted to allow current to pass therethrough when exposed to light.

Claim 13

The combination called for in claim 9 wherein the switching means is adapted to be actuated, allowing current to pass therethrough, when exposed to an increase in fluid pressure exerted by the environment adjacent thereto.

Claim 14

The combination called for in claim 9 wherein the switching means is sensitive of externally applied forces, allowing current to pass therethrough upon any change in the intensity of force applied thereto.

Claim 15

The combination called for in claim 9 with the addition of at least one resistor and at least one capacitor in each external trigger circuit, the said circuit being adapted to drain current from the circuit whereby the output of the monostable will be limited to a predetermined period of time.

Claim 16

In an alarm system for a motor vehicle a battery; a circuit connected to opposite poles of the battery including a monostable oscillator for providing an output signal for a set time when the voltage across the battery is changed; an amplifier in the circuit to increase the magnitude of the output signal; an alarm device connected to one terminal of the battery on the vehicle; and current responsive switching means connected to the alarm and the other terminal of the battery in the circuit with the alarm, the switching means being triggered by the output signal thereby delivering a signal to actuate the alarm, said monostable comprising a first transistor, the base thereof being connected through a resistor to the positive terminal of the battery; a second transistor, the base of which is connected to the collector of the first transistor and through a first capacitor to the negative terminal of the battery; and a second capacitor in a branch connecting the base of the first transistor with the collector of the second transistor in a common emitter circuit, wherein the first transistor is biased on and the second transistor is biased off during the static condition while the first transistor is biased off during the operating condition and the monostable is in the operating condition for a period of time dependent upon the time constant of the RC circuit.

Claim 17

In an alarm system for a motor vehicle a battery; a circuit connected to opposite poles of the battery including a monostable oscillator for providing an output signal for a set time when the voltage across the battery is changed; an amplifier in the circuit to increase the magnitude of the output signal; an alarm device connected to one terminal of the battery on the vehicle; and current responsive switching means connected to the alarm and the other terminal of the battery in the circuit with the alarm, the switching means being triggered by the output signal thereby delivering a signal to actuate the alarm, said monostable comprising a first transistor, the base thereof being connected through a resistor to the positive terminal of the battery; a second transistor, the base of which is connected to the collector of the first transistor and through a first capacitor to the negative terminal of the battery; and a second capacitor in a branch connecting the base of the first transistor with the collector of the second transistor in a common emitter circuit, wherein the first transistor is biased on and the second transistor is biased off during the static condition while the first transistor is biased off during the operating condition and the monostable is in the operating condition for a period of time dependent upon the time constant of the RC circuit.