Control circuits

Claim 2

A circuit for generating a trigger pulse having a short duration with respect to the duration of a pulsation from a power source and synchronized to said source comprising, a capacitor coupled to said source, first circuit means responsive to the drop in the magnitude of said pulsation to a value below the magnitude of the voltage on said capacitor for charging said capacitor from said source to a maximum voltage which is a small percentage of the peak voltage of said source, said capacitor charging during substantially said entire source pulsation, and second circuit means for discharging said capacitor near the zero crossover point of said pulsation in a time period short with respect to the duration of the charging time of said capacitor to generate said trigger pulse.

Claim 3

The combination recited in claim 1 wherein said first circuit means includes a first resistor connected in series with said capacitor, said series combination of capacitor and first resistor connected across said source, and said second circuit means comprises a second resistor and a diode connected in series with each other between one side of said source and the junction of said capacitor and said first resistor, said second resistor being small relative to said first resistor, said diode being reverse biased during substantially said entire source pulsation and forward biased near the zero crossover point of said pulsation to discharge said capacitor near the zero crossover point of said pulsation.

Claim 4

The combination recited in claim 2 wherein said first resistor varies in magnitude in response to changes in an external condition.

Claim 5

The combination recited in claim 1 further including an electronic power switching device and transfer means for applying said trigger pulse to the control terminal of said switching device.

Claim 6

The combination recited in claim 1 wherein said first circuit means includes sensor circuit means responsive to an external condition for controlling said first circuit means to generate said trigger pulse only in response to the occurrence of a preselected condition.

Claim 7

The combination recited in claim 1 wherein said first circuit means includes sensor circuit means for varying the magnitude of said trigger pulses in response to changes in an external condition.

Claim 8

The combination recited in claim 4 wherein said power switching means includes a semiconductor device.

Claim 9

The combination recited in claim 4 wherein said power switching device is a silicon controlled rectifier.

Claim 10

The combination recited in claim 5 wherein said sensor circuit means comprises, a transistor switch, a condition response resistor means coupled to said switch for changing the state of said switch in response to an external condition, and circuit means for actuating said first and second circuit means in response to the state of said transistor switch.

Claim 11

The combination recited in claim 5 wherein said sensor circuit means comprises, circuit means for substantially short circuiting said capacitor upon the occurrence of a preselected condition.

Claim 12

The combination recited in claim 5 wherein said sensor circuit means comprises, a semiconductor amplifier having two opposite saturated states, each state of said amplifier corresponding to one state of said power switching device, condition responsive resistor means coupled to said amplifier to drive said amplifier to one of said opposite states upon the occurrence of a preseleCted condition, means for actuating said first and second circuit means in response to the state of said amplifier.

Claim 13

The combination recited in claim 6 wherein said sensor circuit means comprises a condition responsive resistor means in series with said capacitor and in the path of the charging current flowing to said capacitor.

Claim 14

The combination recited in claim 8 wherein said silicon controlled rectifier has cathode, anode and gate electrodes, said cathode and anode electrodes being connected across said source, and further including third circuit means for holding said gate electrode at a first potential, and fourth circuit means including said capacitor and diode for driving said cathode electrode to a second potential negative with respect to said first potential near the zero point of said source pulsation.

Claim 15

A circuit for generating trigger pulses which are synchronized to a pulsating source comprising, first and second terminals for connection to said source, a first resistor connected to said first terminal and one side of a capacitor, the other side of said capacitor connected to said second terminal, said first resistor and said capacitor forming a charging path for said capacitor having a long time constant relative to the duration of the pulsations of said source, a discharge path coupled to said capacitor having a short time constant relative to the time constant of said charging path and including a diode, and means for reverse biasing said diode during substantially said entire source pulsation while said capacitor is charging and forward biasing said diode near the zero crossover point of said source pulsation to actuate said discharge path, whereby said capacitor is discharged near the zero crossover point of said source pulsation.

Claim 16

A circuit for generating trigger pulses which are synchronized to a pulsating source comprising, first and second terminals for connection to said source, a first resistor connected to said first terminal and one side of a capacitor, the other side of said capacitor connected to said second terminal, said first resistor and said capacitor forming a charging path for said capacitor having a long time constant relative to the duration of the pulsations of said source, a discharge path coupled to said capacitor having a short time constant relative to the time constant of said charging path and including a diode, and means for reverse biasing said diode during substantially said entire source pulsation while said capacitor is charging and forward biasing said diode near the zero crossover point of said source pulsation to actuate said discharge path, whereby said capacitor is discharged near the zero crossover point of said source pulsation.