Fail-safe pulsating peak detection circuit

Claim 2

A fail-safe peak detector for detecting a pulsating input signal and for producing an output signal which is independent of the pulse width of the pulsating input signal comprising, a source of coded pulsating input signals having a low duty cycle in comparison to the pulse repetition rate, a first coupling circuit connected to said source of coded pulsating input signals, a voltage-to-current converter having its input connected to said first coupling circuit, an AC-to-DC converter connected to the output of said voltage-to-current converter by a second coupling circuit, and an integrating circuit means coupled to the output of said AC-to-DC converter for causing load current to continue to flow during the interval between successive coded input pulses and said peak detector being incapable of increasing said load current during a critical circuit or component failure.

Claim 3

A fail-safe peak detector as defined in claim 1, wherein said first coupling means comprises a transformer having a primary and a pair of secondary windings.

Claim 4

A fail-safe peak detector as defined in claim 1, wherein said voltage-to-current converter comprises an amplifying circuit having two active elements.

Claim 5

A fail-safe peak detector as defined in claim 1, wherein said voltage-to-current converter comprises a class B push-pull amplifier.

Claim 6

A fail-safe peak detector as defined in claim 1, wherein said AC-to-DC converter comprises a full-wave bridge rectifier.

Claim 7

A fail-safe peak detector as defined in claim 1, wherein said second coupling circuit comprises a transformer having a pair of primary windings and a secondary winding.

Claim 8

A fail-safe peak detector as defined in claim 1, wherein said integrating circuit means includes an electromagnetic relay.

Claim 9

A fail-safe peak detector as defined in claim 7, wherein said electromagnetic relay includes a magnetic coil coupled to the output of said AC-to-DC converter and an electrical contact connected to an indication circuit.

Claim 10

A fail-safe peak detector as defined in claim 8, wherein said magnetic coil includes a series inductance and resistance elements.

Claim 11

A fail-safe peak detector as defined in claim 9, wherein the time consTant of said series inductance and resistance elements is substantially longer than the pulse repetition period of said coded pulsating input signal.

Claim 12

A fail-safe current-type of peak detection circuit comprising a source of coded pulsating signals having a low duty cycle in comparison with the pulse repetition rate, an input transformer having a primary winding electrically connected to said pulsating signal source and having a pair of secondary windings, a push-pull amplifier, said pair of secondary windings electrically connected to the inputs of said push-pull amplifier, and an output transformer having a pair of primary windings and a secondary winding, said pair of secondary windings electrically connected to the output of said push-pull amplifier, a rectifier having its input terminals connected to said secondary winding and having its output terminals connected to a coil of an electromagnetic relay which remains picked up during the off periods of said coded pulsating signals and which is incapable of being picked up by a critical circuit or component failure.

Claim 13

A fail-safe current-type of peak detection circuit comprising a source of coded pulsating signals having a low duty cycle in comparison with the pulse repetition rate, an input transformer having a primary winding electrically connected to said pulsating signal source and having a pair of secondary windings, a push-pull amplifier, said pair of secondary windings electrically connected to the inputs of said push-pull amplifier, and an output transformer having a pair of primary windings and a secondary winding, said pair of secondary windings electrically connected to the output of said push-pull amplifier, a rectifier having its input terminals connected to said secondary winding and having its output terminals connected to a coil of an electromagnetic relay which remains picked up during the off periods of said coded pulsating signals and which is incapable of being picked up by a critical circuit or component failure.

Claim 14

A fail-safe current-type of peak detection circuit as defined in claim 11, wherein said coded pulsating signal source comprises a high frequency signal source having a duty cycle of approximately 10 percent of the time.

Claim 15

A fail-safe current-type of peak detection amplifier includes a pair of semiconductive devices operating in class B service.

Claim 16

A fail-safe current-type of peak detection amplifier includes a pair of semiconductive devices operating in class B service.

Claim 17

A fail-safe current-type of peak detection circuit as defined in claim 11, wherein said rectifier comprises a full-wave bridge rectifier.

Claim 18

A fail-safe current-type of peak detection circuit as defined in claim 11, said coil of said electromagnetic relay comprises a series conductive resistive circuit having a time constant which is relatively large in comparison with said pulse repetition rate.