Intrusion alarm apparatus

Claim 2

In an A.C.-powered alarm apparatus having: an electrical plug for insertion in an A.C. power socket; and an electrical circuit connected to said plug and including: capacitive switch means; and means for signalling an alarm in response to the operation of said capacitive switch means; the improvement which comprises: test switch means in said circuit which is operable a. in a first position to disable said alarm signalling means from being operated by said capacitive switch means, and b. in a second position to enable said alarm signalling means for operation by said capacitive switch means; and electrically-energized polarity indicator means connected to said test switch means a. in said first position of the latter to indicate whether the plug is inserted in the A.C. power socket with the correct polarity for operating said alarm signalling means, and b. to be disabled in said second position of the test switch.

Claim 3

An alarm apparatus according to claim 1 wherein said polarity indicator means is a glow discharge tube which a. in said first position of said test switch means is connected between one terminal of said plug and said capacitive switch means for operation by the latter, and b. in said second position of said test switch means is open-circuited.

Claim 4

An alarm apparatus according to claim 2, wherein said means for signalling an alarm comprises an alarm signalling device and an SCR connected in series with each other across the terminals of said plug in said second position of said test switch means, said SCR having a gate electrode operatively coupled to said capacitive switch means in said second position of said test switch means to turn on the SCR in response to actuation of said capacitive switch means.

Claim 5

In an A.C.-powered, touch-activated alarm apparatus having: an alarm signalling device; an SCR operatively connected to said alarm signalling device to activate the latter when the SCR is turned on; an electrical plug for insertion in an A.C. power socket; a sensor operatively coupled to said SCR to turn on the SCR in response to the introduction in circuit with the sensor of a body having appreciable capacitance; and a circuit for connecting said plug to said SCR and said alarm signalling device to energize them from said A.C. power socket; the improvement which comprises: electrically energizable polarity indicating means for indicating whether said plug is inserted in said A.C. power socket with the correct polarity; and test switch means in said circuit operable: a. in a first position to operatively connect said polarity indicating means to said plug for energization from said A.C. power socket if the plug polarity is correct and to disable said SCR from being turned on from said sensor; and b. in a second position to disable said polarity indicating means from being energized and to connect said SCR for operation from said sensor.

Claim 6

In an A.C.-powered, touch-activated alarm apparatus having: an alarm signalling device; an SCR operatively connected to said alarm signalling device to activate the latter when the SCR is turned on; an electrical plug for insertion in an A.C. power socket; a sensor operatively coupled to said SCR to turn on the SCR in response to the introduction in circuit with the sensor of a body having appreciable capacitance; and a circuit for connecting said plug to said SCR and said alarm signalling device to energize them from said A.C. power socket; the improvement which comprises: electrically energizable polarity indicating means for indicating whether said plug is inserted in said A.C. power socket with the correct polarity; and test switch means in said circuit operable: a. in a first position to operatively connect said polarity indicating means to said plug for energization from said A.C. power socket if the plug polarity is correct and to disable said SCR from being turned on from said sensor; and b. in a second position to disable said polarity indicating means from being energized and to connect said SCR for operation from said sensor.

Claim 7

An alarm apparatus according to claim 4, wherein said circuit includes: a bias resistor connected between the cathode and gate of the SCR; a first glow discharge tube connected between said sensor and the gate of the SCR; and a second resistor connected between the cathode of the SCR and said test switch means; and wherein: said polarity indicating means is a second glow discharge tube connected in series with said second resistor between said test switch means and the cathode of the SCR; said test switch means in its first position connects said second glow discharge tube and said second resistor to one terminal of said plug and provides a connection from the gate of the SCR to said sensor which short circuits said first glow discharge tube; and said test switch means in its second position open circuits said second glow discharge tube and said second resistor, connects said one terminal of the plug to the cathode of the SCR, and open-circuits said last-mentioned connection from the gate of the SCR to said sensor.

Claim 8

An alarm apparatus according to claim 5, wherein said circuit includes: a capacitor and a variable resistor connected in series with each other between said sensor and first glow discharge tube.