A-c voltage detector

Claim 2

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, comparing means, said comparing means including signal input means, threshold input means and output means, threshold voltage supply means, means for connecting said threshold voltage supply means to said threshold input means to establish a threshold voltage range for said comparing means, means for connecting said input terminal means to said signal input means, output voltage control means for establishing a first voltage at said output terminal means when the voltage at said signal input means is outside said threshold voltage range and for establishing a second voltage at said output terminal means when the voltage at said signal input means is within said threshold voltage range, means for connecting said voltage control means to the output means of said comparing means and time-delay means for delaying the establishment of said second voltage for a time greater than the time required for the voltage at said signal input means to vary through said threshold voltage range.

Claim 3

A circuit as set forth in claim 1 in which said comparing means comprises an operational amplifier having non-inverting and inverting inputs which serve alternately and severally as signal input means and threshold input means.

Claim 4

A circuit as set forth in claim 2 in which said means for connecting said input terminal means to said signal input means includes unidirectional conducting means.

Claim 5

A circuit as set forth in claim 1 in which said comparing means comprises first and second operational amplifiers each having non-inverting and inverting inputs, one input of each amplifier serving as threshold input means and the other input of each amplifier serving as signal input means.

Claim 6

A circuit as set forth in claim 1 in which one of said input terminal means is at the same potential as one of said output terminal means.

Claim 7

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, comparing means having signal input means, threshold input means and output means, threshold voltage supply means, means for connecting said threshold voltage supply means to said threshold input means to establish a threshold voltage range for said comparing means, means for connecting said input terminal means to said signal input means, said comparing means serving to establish a first voltage at the output means thereof when the voltage at said signal input means is outside said threshold voltage range and to establish a second voltage at the output means thereof when the voltage at said signal input means is within said threshold voltage range, discriminator means for establishing a first output voltage at said output terminal means when said first voltage appears at the output means of said comparing means and for establishing a second output voltage at said output terminal means when said second voltage appears at the output means of said comparing means for a time sufficient to allow an a-c input voltage polarity reversal to occur, and means for connecting said discriminator means to said comparing means and to said output terminal means.

Claim 8

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, comparing means having signal input means, threshold input means and output means, threshold voltage supply means, means for connecting said threshold voltage supply means to said threshold input means to establish a threshold voltage range for said comparing means, means for connecting said input terminal means to said signal input means, said comparing means serving to establish a first voltage at the output means thereof when the voltage at said signal input means is outside said threshold voltage range and to establish a second voltage at the output means thereof when the voltage at said signal input means is within said threshold voltage range, discriminator means for establishing a first output voltage at said output terminal means when said first voltage appears at the output means of said comparing means and for establishing a second output voltage at said output terminal means when said second voltage appears at the output means of said comparing means for a time sufficient to allow an a-c input voltage polarity reversal to occur, and means for connecting said discriminator means to said comparing means and to said output terminal means.

Claim 9

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, first and second differential switching means each having signal input means, threshold input means and output means, means for establishing threshold voltages at said threshold input means, means for connecting said input terminal means to said signal input means, output voltage control means for establishing a first voltage at said output terminal means when the voltage at either of said signal input means exceeds the voltage at the respective threshold input means and for establishing a second voltage at said output terminal means when the voltages at both of said signal input means are less than the voltages at the respective threshold input means, means for connecting said voltage control means to the output means of said differential switching means and time-delay means for delaying the establishment of said second voltage for a time greater than the time required for the voltage at said signal input means to vary between said threshold voltages.

Claim 10

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, first and second differential switching means each having signal input means, threshold input means and output means, means for establishing threshold voltages at said threshold input means, means for connecting said input terminal means to said signal input means, output voltage control means for establishing a first voltage at said output terminal means when the voltage at either of said signal input means exceeds the voltage at the respective threshold input means and for establishing a second voltage at said output terminal means when the voltages at both of said signal input means are less than the voltages at the respective threshold input means, means for connecting said voltage control means to the output means of said differential switching means and time-delay means for delaying the establishment of said second voltage for a time greater than the time required for the voltage at said signal input means to vary between said threshold voltages.

Claim 11

A circuit as set forth in claim 7 including means for preconditioning said time-delay means to prevent the latter from appreciably affecting the time required for said output voltage control means to establish said first voltage.

Claim 12

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, a positive comparator and a negative comparator each having signal input means, threshold input means and output means, means for establishing positive and negative threshold voltages at the threshold input means of said positive and negative comparators respectively, means for connecting said input terminal means to the signal input means of said comparators, output voltage control means for establishing a first voltage at said output terminal means when the voltage at said signal input means is outside the voltage range bounded by said positive and negative threshold voltages and for establishing a second voltage at said output terminal means when the voltage at said signal input means is within said voltage range, Time-delay means for delaying the establishment of said second voltage for a time sufficient to allow the voltage at said signal input means to vary between said positive and negative threshold voltages during a-c polarity reversals and means for connecting said time-delay means between said voltage control means and the output means of said comparators.

Claim 13

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, a positive comparator and a negative comparator each having signal input means, threshold input means and output means, means for establishing positive and negative threshold voltages at the threshold input means of said positive and negative comparators respectively, means for connecting said input terminal means to the signal input means of said comparators, output voltage control means for establishing a first voltage at said output terminal means when the voltage at said signal input means is outside the voltage range bounded by said positive and negative threshold voltages and for establishing a second voltage at said output terminal means when the voltage at said signal input means is within said voltage range, Time-delay means for delaying the establishment of said second voltage for a time sufficient to allow the voltage at said signal input means to vary between said positive and negative threshold voltages during a-c polarity reversals and means for connecting said time-delay means between said voltage control means and the output means of said comparators.

Claim 14

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, first and second amplifying means each having signal input means, threshold input means and output means, means for establishing positive and negative threshold voltages at the threshold input means of said first and second amplifying means respectively, means for connecting said input terminal means to said signal input means, means for connecting together the output means of said amplifying means, voltage supply means having a positive terminal, a negative terminal and a common electrically therebetween, means for connecting said positive and negative terminals to said amplifying means, output voltage control means for controlling the voltage between said output terminal means, means for connecting said voltage control means between said common and one terminal of said voltage supply means, capacitance means and means for connecting said capacitance means to said voltage control means and to the output means of said amplifying means.

Claim 15

In a circuit for detecting the presence or absence of an a-c voltage, in combination, input terminal means, output terminal means, first and second amplifying means each having signal input means, threshold input means and output means, means for establishing positive and negative threshold voltages at the threshold input means of said first and second amplifying means respectively, means for connecting said input terminal means to said signal input means, means for connecting together the output means of said amplifying means, voltage supply means having a positive terminal, a negative terminal and a common electrically therebetween, means for connecting said positive and negative terminals to said amplifying means, output voltage control means for controlling the voltage between said output terminal means, means for connecting said voltage control means between said common and one terminal of said voltage supply means, capacitance means and means for connecting said capacitance means to said voltage control means and to the output means of said amplifying means.

Claim 16

A circuit for detecting the presence or absence of an a-c voltage, in combination, a-c input terminal means, output terminal means, differential switching means having first and second input means and output means, means for establishing a first quiescent threshold voltage at said first input means, means for establishing a second quiescent threshold voltage at said second input means, means for connecting said a-c input terminal means to said first and second input means to apply thereto respective positive and negative half-cycles of the a-c input voltage, means for introducing a predetermined d-c level into the voltage applied to said first and second input means, output voltage control means for establishing a first output voltage at said output terminal means when the voltage applied to the input means of said differential switching means is not between said first and second quiescent threshold voltages and for establishing a second output voltage at said output terminal means when the voltage applied to the input means of said differential switching means is between said first and second quiescent threshold voltages, means for connecting said output voltage control means the output means of said differential switching means and time-delay means for delaying the establishment of said second output voltage for a time greater than the time required for the voltage applied to the input means of said differential switching means to vary between said first and second quiescent threshold voltages.

Claim 17

A circuit for detecting the presence or absence of an a-c voltage, in combination, a-c input terminal means, output terminal means, differential switching means having first and second input means and output means, means for establishing a first quiescent threshold voltage at said first input means, means for establishing a second quiescent threshold voltage at said second input means, means for connecting said a-c input terminal means to said first and second input means to apply thereto respective positive and negative half-cycles of the a-c input voltage, means for introducing a predetermined d-c level into the voltage applied to said first and second input means, output voltage control means for establishing a first output voltage at said output terminal means when the voltage applied to the input means of said differential switching means is not between said first and second quiescent threshold voltages and for establishing a second output voltage at said output terminal means when the voltage applied to the input means of said differential switching means is between said first and second quiescent threshold voltages, means for connecting said output voltage control means the output means of said differential switching means and time-delay means for delaying the establishment of said second output voltage for a time greater than the time required for the voltage applied to the input means of said differential switching means to vary between said first and second quiescent threshold voltages.

Claim 18

A circuit for detecting the presence or absence of an a-c voltage, in combination, a-c input terminal means, output terminal means, amplifying means having first and second input means and output means, means for establishing first and second quiescent threshold voltages at said first and second input means respectively, first unidirectional conducting means for connecting said first input means to said a-c input terminal means when the a-c voltage at said a-c input terminal means has a first polarity, second unidirectional conducting means for connecting said second input means to said a-c input terminal means when the voltage at said a-c input terminal means has a second polarity, d-c voltage supply means, a voltage divider, means for connecting said input terminal means to said d-c voltage supply means through said voltage divider, output voltage control means, means for connecting said output voltage control means to said d-c voltage supply means and to the output means of said amplifying means, time-delay means and means for connecting said time-delay meAns to the output means of the said amplifying means and to said output voltage control means.

Claim 19

A circuit for detecting the presence or absence of an a-c voltage, in combination, a-c input terminal means, output terminal means, amplifying means having first and second input means and output means, means for establishing first and second quiescent threshold voltages at said first and second input means respectively, first unidirectional conducting means for connecting said first input means to said a-c input terminal means when the a-c voltage at said a-c input terminal means has a first polarity, second unidirectional conducting means for connecting said second input means to said a-c input terminal means when the voltage at said a-c input terminal means has a second polarity, d-c voltage supply means, a voltage divider, means for connecting said input terminal means to said d-c voltage supply means through said voltage divider, output voltage control means, means for connecting said output voltage control means to said d-c voltage supply means and to the output means of said amplifying means, time-delay means and means for connecting said time-delay meAns to the output means of the said amplifying means and to said output voltage control means.