US 4,797,608 AGranted

D.C. power monitor

AssigneeDigital Equipment Corporation

InventorRandall A. White

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Abstract

A DC power monitor includes a reference voltage and voltage dividers for obtaining voltages which are respectively above and below the reference level when the voltages being monitored are at their nominal value. Comparators compare the divided voltages with the reference and the comparator outputs are Anded and coupled through a flip flop to a bicolor LED which is one color when the voltages are in tolerance and another color when out of tolerance.

Claims9

Dependent claims

A DC power monitor for monitoring at least first and second voltages comprising:

means for establishing a reference voltage level from a third voltage source;
first means for dividing said first voltage to obtain a first divided voltage higher than said reference voltage when said first voltage is at its nominal level;
a first comparator for comparing said first divided voltage and said reference voltage to provide a first output having a first level when said first divided voltage is above said reference voltage and a second level when below;
second means for dividing said second voltage to obtain a second divided voltage higher than said reference when said second voltage is at its nominal value;
a second comparator for comparing said second divided voltage with said reference having an output at said first level when said second divided voltage is above said reference voltage and a second level when below;
third means for dividing said first voltage to obtain a third divided voltage lower than said reference voltage when said first voltage is at its nominal value;
a third comparator for comparing said third divided voltage with said reference voltage and providing an output at said first level when said third divided voltage is lower than said reference voltage and of said second level when above;
fourth means for dividing said second voltage to obtain a fourth divided voltage lower than said reference voltage;
a fourth comparator for comparing said fourth divided voltage with said reference voltage and providing an output at said first level when said third divided voltage is lower than said reference voltage and of said second level when above;
said first and second voltages are respectively positive and negative voltages, wherein said third source voltage is also a positive voltage and wherein said first voltage of said first and third voltage dividing means is coupled to one end of its respective voltage dividing means with the other end thereof coupled to ground and said second, negative voltage of said second and fourth voltage dividing means is coupled to one end of its respective voltage dividing means with the other end thereof coupled to said third source voltage, whereby in each case positive voltages can be provided as inputs to said comparators for comparison with said positive reference voltage;
means for Anding the outputs of said first, second, third and fourth comparators;
an LED with first and second cathodes providing two colors;
and
means having as an input the output of said means Anding said comparator signals, said means providing first and second outputs to said first and second cathodes for respectively energizing a first and second color thereof, said means providing a signal which energizes one color of said LED when a signal is present from said Anding means and energizing the other color when said signal is not present from said Anding means.

11 more elements

A method for monitoring at least first and second DC voltages being positive and negative voltages, respectively, comprising:

establishing a reference voltage level from a third voltage source, said third voltage source being a positive voltage;
coupling said first voltage to one end of a first and second means for dividing and coupling the other end to ground;
dividing the first voltage in the first dividing means to obtain a first divided voltage higher than said reference voltage;
comparing said first divided voltage with said reference voltage to provide a first output;
dividing said first voltage in the second dividing means to obtain a second divided voltage lower than said reference voltage;
comparing said second divided voltage with said reference voltage to provide a second output;
coupling said second voltage to one end of a third and fourth means for dividing and coupling the other end to the third voltage, whereby in each case positive voltages can be provided as inputs for comparing with the reference voltage;
dividing said second voltage in the third dividing means to obtain a third divided voltage lower than said reference voltage;
comparing said third divided voltage with said reference voltage to provide a third output;
dividing said second voltage in the fourth dividing means to obtain a fourth divided voltage higher than said reference voltage;
comparing said fourth divided voltage with said reference voltage to provide a fourth output;
Anding said first, second, third and fourth outputs to obtain a fifth output;
and
energizing one color cathode of a two color LED if said fifth output is present and the other cathode if said fifth output is not present.

11 more elements

Dependencies are inferred from the claim text.

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Abstract

A DC power monitor for monitoring at least first and second voltages comprising:

means for establishing a reference voltage level from a third voltage source;
first means for dividing said first voltage to obtain a first divided voltage higher than said reference voltage when said first voltage is at its nominal level;
a first comparator for comparing said first divided voltage and said reference voltage to provide a first output having a first level when said first divided voltage is above said reference voltage and a second level when below;
second means for dividing said second voltage to obtain a second divided voltage higher than said reference when said second voltage is at its nominal value;
a second comparator for comparing said second divided voltage with said reference having an output at said first level when said second divided voltage is above said reference voltage and a second level when below;
third means for dividing said first voltage to obtain a third divided voltage lower than said reference voltage when said first voltage is at its nominal value;
a third comparator for comparing said third divided voltage with said reference voltage and providing an output at said first level when said third divided voltage is lower than said reference voltage and of said second level when above;
fourth means for dividing said second voltage to obtain a fourth divided voltage lower than said reference voltage;
a fourth comparator for comparing said fourth divided voltage with said reference voltage and providing an output at said first level when said third divided voltage is lower than said reference voltage and of said second level when above;
said first and second voltages are respectively positive and negative voltages, wherein said third source voltage is also a positive voltage and wherein said first voltage of said first and third voltage dividing means is coupled to one end of its respective voltage dividing means with the other end thereof coupled to ground and said second, negative voltage of said second and fourth voltage dividing means is coupled to one end of its respective voltage dividing means with the other end thereof coupled to said third source voltage, whereby in each case positive voltages can be provided as inputs to said comparators for comparison with said positive reference voltage;
means for Anding the outputs of said first, second, third and fourth comparators;
an LED with first and second cathodes providing two colors;
and
means having as an input the output of said means Anding said comparator signals, said means providing first and second outputs to said first and second cathodes for respectively energizing a first and second color thereof, said means providing a signal which energizes one color of said LED when a signal is present from said Anding means and energizing the other color when said signal is not present from said Anding means.

11 more elements