Operation test circuit for fire detectors

Claim 2

A test circuit for fire alarm systems and the like of a type in which first and second electrical lines are bridged by a plurality of detectors, each detector becoming conductive upon detection of a condition such as fire and upon receipt of a predetermined number of electrical test pulses which are transmitted across said lines, comprising: means for generating test pulses and supplying them to the detectors; means for generating an alarm signal when said lines are connected together by at least one conductive detector, said generating means being connected to said first line; means for disabling said generating means, said disabling means being connected in series with said generating means; a first circuit for producing a confirmation signal when said lines are connected together by a conductive detector; a delay circuit for delaying production of said confirmation signal for a predetermined period of time after said lines are connected together by a conductive detector; and a second circuit for deactivating said disabling means in response to production of said confirmation signal, whereby generation of an alarm signal by said generating means is permitted.

Claim 3

A test circuit for fire alarm systems and the like of a type in which first and second electrical lines are bridged by a plurality of detectors, each detector becoming conductive upon detection of a condition such as fire and upon receipt of a predetermined number of electrical test pulses which are transmitted across said lines, and being resettable to a nonconductive state by a reset voltage applied across said lines, comprising: means for generating test pulses and supplying them to the detectors; relay means for generating an alarm signal when said lines are connected together by at least one conductive detector, said relay means being connected to said first line; a control resistor for preventing said relay means from latching, said control resistor being connected in series with said relay means; a first circuit for producing a confirmation signal when said lines are connected together by a conductive detector; an RC delay circuit for delaying production of said confirmation signal for a predetermined period of time after said lines are connected together by a conductive detector; a second circuit for shorting across said control resistor in response to production of said confirmation signal, whereby generation of an alarm signal by said relay means is permitted; and means for applying said reset voltage across said lines.

Claim 4

A test circuit for fire alarm systems and the like of a type in which first and second electrical lines are bridged by a plurality of detectors, each detector becoming conductive upon detection of a condition such as fire and upon receipt of a predetermined number of electrical test pulses which are transmitted across said lines, and being resettable to a nonconductive state by a reset voltage applied across said lines, comprising: means for generating test pulses and supplying them to the detectors; relay means for generating an alarm signal when said lines are connected together by at least one conductive detector, said relay means being connected to said first line; a control resistor for preventing said relay means from latching, said control resistor being connected in series with said relay means; a first circuit for producing a confirmation signal when said lines are connected together by a conductive detector; an RC delay circuit for delaying production of said confirmation signal for a predetermined period of time after said lines are connected together by a conductive detector; a second circuit for shorting across said control resistor in response to production of said confirmation signal, whereby generation of an alarm signal by said relay means is permitted; and means for applying said reset voltage across said lines.

Claim 5

The test circuit of claim 1, wherein said first circuit comprises a transistor with its base connected to said first line through a Zener diode.

Claim 6

The test circuit of claim 2, wherein said RC delay circuit comprises a capacitor and said second circuit comprises a transistor with its base connected to said capacitor through a Zener diode.

Claim 7

The test circuit of claim 1 or 2, further comprising means for momentarily interrupting current flow through said first line in response to production of a confirmation signal.

Claim 8

The test circuit of claim 2, wherein the detectors are normally operated on a supply voltage, wherein the test pulses have a voltage exceeding said supply voltage, wherein the reset voltage exceeds the voltage of the test pulses, and wherein the circuit further comprises a gate which is operated by timing pulses and said confirmation signal.

Claim 9

The test circuit of claims 1 or 2, further comprising means for detecting when a production of test pulses fails to produce a confirmation pulse.

Claim 10

The test circuit of claim 2, wherein said applying means operates in a manner that said reset voltage is produced after a predetermined group of detectors have been tested by application of test pulses.

Claim 11

The test circuit of claim 8, wherein there are a plurality of said first lines and said reset voltage is applied to a next one of said first lines after all detectors connected to a prior one of said first lines have been tested.

Claim 12

The test circuit of claim 9, further comprising: a detector address counter for locating an address of a counter under test by counting a number of test pulses supplied to a particular one of said first lines; an alarm line counter for counting a particular one of said first lines to which test pulses are supplied; and a display device for indicating the particular first line and the particular address of a detector which has been determined to be inoperative after application of test pulses thereto.

Claim 13

A test circuit for fire alarm systems and the like of a type in which first and second electrical lines are bridged by a plurality of detectors, each detector becoming conductive upon detection of a condition such as a fire and upon receipt of a predetermined number of electrical test pulses which are transmitted across said lines, comprising: means for generating test pulses and supplying them to the detectors; means for generating an alarm signal when said lines are connected together by at least one conductive detector; means for disabling said generating means; a first circuit for producing a confirmation signal when said lines are connected together by a conductive detector; a delay circuit for delaying production of said confirmation signal for a predetermined period of time after said lines are connected together by a conductive detector; and a second circuit for deactivating said disabling means in response to production of said confirmation signal, whereby generation of an alarm signal by said generating means is permitted.

Claim 14

A test circuit for fire alarm systems and the like of a type in which first and second electrical lines are bridged by a plurality of detectors, each detector becoming conductive upon detection of a condition such as a fire and upon receipt of a predetermined number of electrical test pulses which are transmitted across said lines, comprising: means for generating test pulses and supplying them to the detectors; means for generating an alarm signal when said lines are connected together by at least one conductive detector; means for disabling said generating means; a first circuit for producing a confirmation signal when said lines are connected together by a conductive detector; a delay circuit for delaying production of said confirmation signal for a predetermined period of time after said lines are connected together by a conductive detector; and a second circuit for deactivating said disabling means in response to production of said confirmation signal, whereby generation of an alarm signal by said generating means is permitted.