Device for limiting the working voltage for mechanical switches in telephony
First Claim
Patent Images
1. A device for connection to a first telephone line and a second telephone line, the device comprising:
- a mechanical switch having a first terminal coupled to the first telephone line and a second terminal, the mechanical switch being movable from a first position to a second position;
a first circuit including a zener diode and a second device;
the zener diode being coupled to the first and second terminals of the mechanical switch for setting a maximum working voltage across the mechanical switch andthe second device being coupled to the first and second terminals of the mechanical switch, the second device provides no current when the mechanical switch is in the first position and the second device further provides an output current when the switch is in the second position; and
a control circuit electrically coupled to the first circuit and responsive to the output current for providing an activation output signal to correct the first and second telephone lines to a talk circuit.
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Abstract
Device for limiting the working voltage for mechanical switches in telephony includes terminals for connection to a telephone line, a connection and power supply branch for a control circuit extending from a first terminal, the branch having a first switch, the cathode terminal of a first Zener diode and the source terminal of a first MOSFET transistor being connected to the output terminal of the first switch, the gate terminal of the first MOSFET transistor being connected, through the anode terminal of the Zener diode, to the first terminal. The current absorbed by the device may be adjusted.
13 Citations
21 Claims
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1. A device for connection to a first telephone line and a second telephone line, the device comprising:
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a mechanical switch having a first terminal coupled to the first telephone line and a second terminal, the mechanical switch being movable from a first position to a second position; a first circuit including a zener diode and a second device; the zener diode being coupled to the first and second terminals of the mechanical switch for setting a maximum working voltage across the mechanical switch and the second device being coupled to the first and second terminals of the mechanical switch, the second device provides no current when the mechanical switch is in the first position and the second device further provides an output current when the switch is in the second position; and a control circuit electrically coupled to the first circuit and responsive to the output current for providing an activation output signal to correct the first and second telephone lines to a talk circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A device for limiting a working voltage for mechanical switches in telephony, comprising:
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terminals for connection to a telephone line; a connection and power supply branch for a control circuit coupled to a first terminal and having a first switch including an output terminal, a first zener diode having a first cathode terminal coupled to the output terminal, a first MOSFET depletion transistor having a source terminal coupled to the output terminal, a gate terminal coupled to an anode terminal of the first zener diode and the first terminal; and means for adjusting a current absorbed by the device, including; a third MOSFET transistor having a drain terminal coupled to a drain terminal of the first MOSFET depletion transistor, a source terminal coupled to the second terminal, a gate terminal and the drain terminal of the third MOSFET transistor coupled to a gate terminal of a second MOSFET transistor having a source terminal coupled to a terminal of the control circuit and a drain terminal coupled to the second terminal; and a resistor that couples the first cathode terminal of the first zener diode and the source terminal of the first MOSFET depletion transistor to the output terminal of the switch.
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17. A device for limiting a working voltage for mechanical switches in telephony, comprising:
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terminals for connection to a telephone line; a connection and power supply branch circuit coupled to a first terminal and having a first switch including an output terminal, a first zener diode having a first cathode terminal coupled to the output terminal, a first MOSFET transistor having a source terminal coupled to the output terminal of the first zener diode and the first terminal; and a control circuit coupled to the connection and power supply branch circuit, for controlling a current consumed by the device, the control circuit including; a third MOSFET transistor having a drain terminal coupled to a drain terminal of the first MOSFET transistor, a source terminal coupled to the second terminal, a gate terminal and the drain terminal of the third MOSFET transistor coupled to a gate terminal of a second MOSFET transistor having a source terminal coupled to a terminal of the control circuit and a drain terminal coupled to a second terminal; and a resistor that couples the first cathode terminal of the first zener diode and the source terminal of the first MOSFET depletion transistor to the output terminal of the first switch.
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18. A device for limiting a working voltage for mechanical switches in telephony, comprising:
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terminals for connection to a telephone line; a connection and power supply branch circuit coupled to a first terminal and having a first switch including an output terminal, a first zener diode having a first cathode terminal coupled to the output terminal, a first MOSFET transistor having a source terminal coupled to the output terminal of the first zener diode and the first terminal; and a control circuit coupled to the connection and power supply branch circuit, for controlling a current consumed by the device, the control circuit including; a third MOSFET transistor having a drain terminal coupled to a drain terminal of the first MOSFET transistor, a source terminal coupled to the second terminal, a gate terminal and the drain terminal of the third MOSFET transistor coupled to a gate terminal of a second MOSFET transistor having a source terminal coupled to a terminal of the control circuit and a drain terminal coupled to a second terminal; and means for controlling an amount of current flowing from the source terminal of the first MOSFET depletion transistor to the drain terminal of the first MOSFET depletion transistor.
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19. A device for limiting a working voltage for a mechanical telephone switchhook, comprising:
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first and second terminals for connection to a telephone line; connection and power supply branch circuit coupled to the first terminal and including; a mechanical switch having an output terminal; a first zener diode having a first cathode terminal coupled to the output terminal; and a first MOSFET transistor having a source terminal coupled to the output terminal, and a gate terminal coupled to the anode terminal of the first zener diode and to the first terminal; switching means for connecting the telephone line to a talk circuit; and a control circuit coupled to the connection and power supply branch, for controlling the switching means, the control circuit including; a second MOSFET transistor and a third MOSFET transistor, the third MOSFET transistor having a drain terminal coupled to a drain terminal of the first MOSFET transistor, a source terminal coupled to the second terminal, a gate terminal and the drain terminal of the third MOSFET transistor coupled to a gate terminal of the second MOSFET transistor, the second MOSFET transistor having a source terminal coupled to a terminal of the switching means, and a drain terminal coupled to the second terminal; and a resistor that couples the first cathode terminal of the first zener diode and the source terminal of the first MOSFET depletion transistor to the output terminal of the mechanical switch.
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20. A device for limiting a working voltage for a mechanical telephone switchhook, comprising:
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first mad second terminals for connection to a telephone line; a connection and power supply branch circuit coupled to the first terminal and including; a mechanical switch having an output terminal; a first zener diode having a first cathode terminal coupled to the output terminal; and a first MOSFET transistor having a source terminal coupled to the output terminal, and a gate terminal coupled to the anode terminal of the first zener diode and to the first terminal; switching means for connecting the telephone line to a talk circuit; and a control circuit, coupled to the connection and power supply branch, for controlling the switching means, the control circuit including; a second MOSFET transistor and a third MOSFET transistor, the third MOSFET transistor having a drain terminal coupled to a drain terminal of the first MOSFET transistor, a source terminal coupled to the second terminal a gate terminal and the drain terminal of the third MOSFET transistor coupled to a gate terminal of the second MOSFET transistor, the second MOSFET transistor having a source terminal coupled to a terminal of the switching means, and a drain terminal coupled to the second terminal; and means for controlling an amount of current flowing from the source terminal of the first MOSFET transistor to the drain terminal of the first MOSFET transistor.
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21. A device for limiting a working voltage for mechanical switches in telephony, comprising:
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terminals for connection to a telephone line; a connection and power supply branch for a control circuit coupled to a first terminal and having a first switch including an output terminal, a first zener diode having a first cathode terminal coupled to the output terminal, a first MOSFET depletion transistor having a source terminal coupled to the output terminal, a gate terminal coupled to an anode terminal of the first zener diode and the first terminal; and means for adjusting a current absorbed by the device, including; a third MOSFET transistor having a drain terminal coupled to a drain terminal of the first MOSFET depletion transistor, a source terminal coupled to the second terminal, a gate terminal and the drain terminal of the third MOSFET transistor coupled to a gate terminal of a second MOSFET transistor having a source terminal coupled to a terminal of the control circuit and a drain terminal coupled to the second terminal; and means for controlling an amount of current flowing from the source terminal of the first MOSFET depletion transistor to the drain terminal of the first MOSFET depletion transistor.
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Specification