Events recorder

Claim 2

A circuit for indicating a change in the status of an alarm circuit comprising: a. switching means responsive to a change in the status of said alarm circuit for providing a series of signal pulses, b. bistable circuit means having first and second input circuits for switching into first and second modes of operation respectively, c. a reactive circuit coupling said switching means to said first input circuit for switching said bistable circuit means into said first mode of operation in response to said signal pulses for indicating a change in status of said alarm circuit, and d. circuit means coupled to said second input circuit for switching said bistable circuit into said second mode of operation for conditioning said bistable switching means to indicate a subsequent change in status of said alarm circuit.

Claim 3

The invention defined in claim 1 wherein: said alarm circuit has a first and a second status of operation; and said switching means is coupled to said alarm circuit to produce said series of pulses each time said alarm circuit switches between said first and second status of operation.

Claim 4

The invention defined in claim 1 wherein: said switching means is an electromechanical device having at least one normally open electrical contact which exhibits contact bounce when closing to provide said series of pulses.

Claim 5

The invention defined in claim 1 wherein: said bistable circuit means requires direct current signals on said first and second input circuits to switch modes of operations, and said reactive circuit charges to a sufficient magnitude in response to said series of pulses to switch said bistable circuit means into said first mode of operation.

Claim 6

The invention defined in claim 1 wherein: said bistable circuit includes a pair of NOR gates coupled to form a flip-flop circuit.

Claim 7

The invention defined in claim 1 wherein: said reactive circuit includes a capacitor which charges to a voltage sufficient to switch said bistable circuit into one of said first and second modes of operation in response to said series of pulses.

Claim 8

In an events recorder for indicating a change in state of an alarm circuit having one state when normal and a second state when abnormal, the combination comprising: a. a source of direct current voltage, b. relay means including a coil connected in circuit with said alarm circuit and normally open resonant contacts connected to said source representing one state of said alarm circuit when open, c. said contacts bounce upon closure to produce a varying direct current voltage representing said other state of said alarm circuit, d. a bistable circuit means having first and second input circuits for switching into first and second modes of operation respectively for indicating said change in state of said alarm circuit, e. a reactive circuit means coupling said relay means to said first input circuit for switching said bistable circuit means into said first mode of operation in response to said varying direct current voltage, and f. circuit means coupled to said second input circuit for switching said bistable circuit into said second mode of operation for conditioning said bistable switching means to indicate a subsequent change in the state of said alarm switching circuit when said resonant contacts open.

Claim 9

In an events recorder for indicating a change in state of an alarm circuit having one state when normal and a second state when abnormal, the combination comprising: a. a source of direct current voltage, b. relay means including a coil connected in circuit with said alarm circuit and normally open resonant contacts connected to said source representing one state of said alarm circuit when open, c. said contacts bounce upon closure to produce a varying direct current voltage representing said other state of said alarm circuit, d. a bistable circuit means having first and second input circuits for switching into first and second modes of operation respectively for indicating said change in state of said alarm circuit, e. a reactive circuit means coupling said relay means to said first input circuit for switching said bistable circuit means into said first mode of operation in response to said varying direct current voltage, and f. circuit means coupled to said second input circuit for switching said bistable circuit into said second mode of operation for conditioning said bistable switching means to indicate a subsequent change in the state of said alarm switching circuit when said resonant contacts open.

Claim 10

The invention defined in claim 7 wherein said reactive circuit means includes a capacitor which charges to a voltage sufficient to switch said bistable circuit means into one of said first and second modes of operation in response to said varying direct current voltage.