Apparatus for providing time delay upon total deenergization

Claim 2

A delay on drop out circuit comprising power supply means, a first charge storage device, a second charge storage device, means for charging said first charge storage device, means for connecting said first charge storage device to said second charge storage device, means for preventing the charging of said second charge storage device while said power supply means is energized and responsive to deenergization of said power supply means for permitting said second charge storage device to charge from said first charge storage device, and means responsive to the charging of said second charge storage device to a predetermined level for producing an output, said means for preventing the charging of said second charge storage device comprising an electric switch connected across said second charge storage device and having a control electrode connected to means including a voltage divider connected to said power supply means for rendering said switch conductive continuously when said power supply means is energized.

Claim 3

The circuit of claim 3, wherein said switch is a bipolar transistor, and said control electrode is the base of the transistor.

Claim 4

The circuit of claim 4, wherein said means for charging said first charge storage device comprises a charging rectifier having means for connecting it in series with said first charge storage device across said voltage divider, said second charge storagE device also being connected in series with said charging rectifier across said voltage divider.

Claim 5

A delay on drop out circuit comprising power supply means, a first charge storage device, a second charge storage device, means for charging said first charge storage device, means for connecting said first charge storage device to said second charge storage device, means for preventing the charging of said second charge storage device while said power supply means is energized and responsive to deenergization of said power supply means for permitting said second charge storage device to charge from said first charge storage device, and means responsive to the charging of said second charge storage device to a predetermined level for producing an output, said means for charging said first charge storage device comprising a third charge storage device connected in series with said first charge storage device and said power supply means.

Claim 6

The circuit of claim 6, further comprising means for clamping the voltage across said first charge storage device while said power supply means is energized, said clamping means comprising a resistor and a voltage-regulating device connected across said power supply means, the junction of said resistor and said regulating device being connected to said first charge storage device, said third charge storage device being connected across said resistor.

Claim 7

The circuit of claim 7, wherein said junction is connected to said first charge storage device by a charging rectifier.

Claim 8

A delay on dropout circuit comprising power supply means including a regulated DC supply having a pair of output terminals, a first charge storage device having means including a charging rectifier for connecting said device between said terminals, a second charge storage device having impedance means connecting said second charge storage device in series with said charging rectifier between said terminals, electric switch means connected across said second charge storage device and having a control electrode connected to a voltage divider connected between said terminals, a semiconductor-controlled switch having a high-impedance charge-sensing circuit including a pair of electrodes of the switch connected across said second charge storage device and having a high-impedance bias circuit including a voltage divider connected in series with said charging rectifier between said terminals and connected to a further electrode of said switch, a semiconductor-controlled rectifier having its principal electrode path connected in series with said charging rectifier between said terminals and having its gate electrode connected to an output electrode of said semiconductor-controlled switch, and means including a relay for connecting said principal electrode path across said first charge storage device, said relay having a switch for discharging said second charge storage device.

Claim 9

A delay on dropout circuit comprising power supply means, a first charge storage device, a second charge storage device, means for charging said first charge storage device from said power supply means, means for connecting said first charge storage device to said second charge storage device, means connected to said power supply means for preventing the charging of said second charge storage device while said power supply means is energized and responsive to deenergization of said power supply means for permitting said second charge storage device to charge from said first charge storage device, and means responsive to the charging of said second charge storage device to a predetermined level for producing an output, the last-mentioned means comprising a semiconductor switch including an anode, a cathode, and a gate, means connecting said anode and said cathode to opposite sides, respectively, of said second charge storage device, and means for applying a bias to said gate, said means for producing an output further comprising a latching relay having a set coil, a reset cOil, and a pair of switches controlled by the coils, means including one of the switches of said pair for energizing said set coil from said power supply means, and means responsive to said semiconductor switch for discharging said first charge storage device through said reset coil when said second charge storage device is charged to said predetermined level, the other switch of said pair being connected across said second charge storage device and being adapted to close when said first charge storage device is discharged through said reset coil.

Claim 10

The circuit of claim 10, wherein said power supply means comprises a pair of AC input terminals connected to rectifier means for supplying DC to said first charge storage device and wherein said set coil and said one switch are connected in series between said AC input terminals.

Claim 11

A delay on dropout circuit comprising power supply means, a first charge storage device, a second charge storage device, means for connecting said first charge storage device to said second charge storage device, means connected to said power supply means for preventing the charging of said second charge storage device while said power supply means is energized and responsive to deenergization of said power supply means for permitting said second charge storage device to charge from said first charge storage device, and means responsive to the charging of said second charge storage device to a predetermined level for producing an output, the last-mentioned means comprising a semiconductor switch including an anode, a cathode, and a gate, means connecting said anode and said cathode to opposite sides, respectively, of said second charge storage device, and means for applying a bias to said gate, said means for charging said first charge storage device to said second charge storage device comprising a single coil-latching relay having a double-throw switch operated by the coil of said relay, said double-throw switch having one position connecting one side of said coil to said power supply means and having another position connecting said side of said coil to said second charge storage device, the other side of said coil being connected to said first charge storage device, said output-producing means further comprising means responsive to said semiconductor switch for energizing said coil when said double-throw switch is in said other position.

Claim 12

The circuit of claim 12, said relay having another switch for discharging said second charge storage device when said double-throw switch is in its said one position.

Claim 13

The circuit of claim 12, further comprising voltage regulator means and means for connecting said voltage regulator means across said first charge storage device.