Under-voltage monitoring device having time delay means for regulated power supplies

Claim 2

In a voltage monitoring system, the combination of; a source of adjustable reference voltage; means for comparing a voltage to be monitored with said reference voltage; switching means responsive to monitored voltage less than said reference voltage coupled to said comparing means; adjustable time delay means; means coupling said adjustable time delay means to said switching means; means included in said coupling means responsive to said switching means for disabling said time delay means in response to monitored voltage less than said reference voltage; and output signaling means coupled to said time delay means and responsive thereto to indicate an undervoltage condition of the monitored voltage.

Claim 3

A voltage monitoring system as set forth in claim 1; wherein said switching means comprises a Schmitt trigger circuit.

Claim 4

A voltage monitoring system as set forth in claim 1; wherein said time delay means includes an adjustable constant current source and a capacitor connected to be charged by said constant current.

Claim 5

A voltage monitoring system as set forth in claim 1; wherein said output signaling means includes a transistor indicating undervoltage condition of the monitored voltage by a turned-on state.

Claim 6

A voltage monitoring system as set forth in claim 1; wherein said switching means comprises a Schmitt trigger and including means for applying the voltage to be monitored to the input thereof.

Claim 7

In a voltage monitoring system, the combination of; trigger means for comparing a voltage to be monitored with a reference voltage; adjustable time delay means; means coupling said adjustable time delay means to said trigger means; indicating means coupled to said time delay means; said trigger means, time delay means and indicating means being adapted to respond to increasing monitored voltage rising above a predetermined level to actuate said indicating means after a predetermined time delay; and wherein said time delay coupling means includes inhibiting means for disabling said time delay means adapted to respond to decreasing monitored voltage falling Below said predetermined level to actuate said indicating means in substantially less than said delay time.

Claim 8

In a voltage monitoring system, the combination of; trigger means for comparing a voltage to be monitored with a reference voltage; adjustable time delay means; means coupling said adjustable time delay means to said trigger means; indicating means coupled to said time delay means; said trigger means, time delay means and indicating means being adapted to respond to increasing monitored voltage rising above a predetermined level to actuate said indicating means after a predetermined time delay; and wherein said time delay coupling means includes inhibiting means for disabling said time delay means adapted to respond to decreasing monitored voltage falling Below said predetermined level to actuate said indicating means in substantially less than said delay time.

Claim 9

In a voltage monitoring system, the combination of; A Schmitt trigger including two bipolar transistors, adjustable means for setting the triggering point and means for applying the voltage to be monitored to the input thereof; a capacitor coupled to an output, normally on, bipolar transistor, said coupling adapted to turn said bipolar transistor off in response to a predetermined charge voltage across said capacitor; a transistor connected across said capacitor and coupled to said Schmitt trigger for discharging said capacitor in response to monitored voltage of less than a predetermined voltage; a transistor connected to supply an adjustable constant current to charge said capacitor; whereby said output transistor is turned off after a predetermined time delay from the instant the monitored voltage rises above said predetermined voltage and is turned off without delay from the instant the monitored voltage falls below said predetermined voltage.

Claim 10

In a voltage monitoring system, the combination of; A Schmitt trigger including two bipolar transistors, adjustable means for setting the triggering point and means for applying the voltage to be monitored to the input thereof; a capacitor coupled to an output, normally on, bipolar transistor, said coupling adapted to turn said bipolar transistor off in response to a predetermined charge voltage across said capacitor; a transistor connected across said capacitor and coupled to said Schmitt trigger for discharging said capacitor in response to monitored voltage of less than a predetermined voltage; a transistor connected to supply an adjustable constant current to charge said capacitor; whereby said output transistor is turned off after a predetermined time delay from the instant the monitored voltage rises above said predetermined voltage and is turned off without delay from the instant the monitored voltage falls below said predetermined voltage.