Solid state ringing switch
First Claim
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1. A switch for providing to a load a signal from an ac source for a predetermined time interval, said switch comprising:
- (a) means for determining when said ac signal crosses another signal in a predetermined direction and generating a signal indicative thereof;
(b) means for synchronizing said indicative signal to a periodic control signal representative of said predetermined ac signal time interval and generating a first output signal when said indicative signal occurs in said predetermined ac signal time interval;
(c) first power output switching means having a closed state which has a substantially constant and low impedance for providing said ac signal to said load;
(d) supply means for generating from said ac signal without introducing any perceptible distortion therein a floating source of power; and
(e) means responsive to said synchronizing means first output signal for using said floating source of power to drive said first power output means into said closed state.
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Abstract
A ringing switch for providing ringing voltage and tripping voltage to the cable pairs of a telephone central office. The switch synchronizes the control signal from a cadence generator with the zero crossing of the ringing voltage to ensure that the voltage at the switch output changes from the ringing voltage to the tripping voltage or vice versa only when the ringing voltage crosses the tripping voltage. Field effect transistors are used to switch the ringing voltage and a silicon controlled rectifier is used to switch the tripping voltage.
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Citations
15 Claims
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1. A switch for providing to a load a signal from an ac source for a predetermined time interval, said switch comprising:
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(a) means for determining when said ac signal crosses another signal in a predetermined direction and generating a signal indicative thereof; (b) means for synchronizing said indicative signal to a periodic control signal representative of said predetermined ac signal time interval and generating a first output signal when said indicative signal occurs in said predetermined ac signal time interval; (c) first power output switching means having a closed state which has a substantially constant and low impedance for providing said ac signal to said load; (d) supply means for generating from said ac signal without introducing any perceptible distortion therein a floating source of power; and (e) means responsive to said synchronizing means first output signal for using said floating source of power to drive said first power output means into said closed state. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A switch for alternately providing to a load a signal from a ringing generator for a predetermined time interval and a tripping signal for a predetermined time interval, said switch comprising:
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(a) means for determining when said ringing signal crosses said tripping signal in a predetermined direction and generating a signal indicative thereof; (b) means for synchronizing said indicative signal to a periodic control signal representative of said predetermined ringing time interval and generating a first output signal when said indicative signal occurs in said predetermined ringing time interval; (c) first power output switching means having a closed state which has a substantially constant and low impedance for providing said ringing signal to said load; (d) second power output switching means having a closed state for providing said tripping signal to said load; and (e) means responsive to said synchronizing means first output signal for generating from said ringing signal without introducing any perceptible distortion therein a signal for driving said first power output means into said closed state. - View Dependent Claims (9, 10, 11)
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12. A switch for alternately providing to a load a signal from a ringing generator for a predetermined time interval and a tripping signal for a predetermined time interval, said switch comprising:
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(a) means for determining when said ringing signal crosses said tripping signal in a predetermined direction and generating a signal indicative thereof; (b) means for synchronizing said indicative signal to a periodic control signal representative of said preedetermined ringing time interval and generating a first output signal when said indicative signal occurs in said predetermined ringing time interval; (c) first power output switching means having a closed state which places a substantially constant and low impedance in series with said ringing generator for providing said ringing signal to said load; (d) second power output switching means having a closed state for providing said tripping signal to said load; and (e) means responsive to said synchronizing means first output signal for generating from said ringing signal without introducing any perceptible distortion therein a signal for driving said first power output means into said closed state. - View Dependent Claims (13, 14, 15)
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Specification