Abstract A motor control device employing a low-power silicon-controlled rectifier in parallel with a power transistor. The siliconcontrolled rectifier initially conducts current from the power source to the load and then triggers the power transistor so that they together conduct the power to the load with the power transistor handling most of the current. The power transistor is turned on by the voltage across a resistor, on a capacitive or inductive reactance element in series with a silicon-controlled rectifier. In another embodiment a diode is used in series with the base of the power transistor and an external pulse is used to back bias the diode to turn off the circuit. In a further embodiment a low-power transistor is used in series with the silicon-controlled rectifier wherein the circuit is turned off by turning off the low-power transistor.
A control device for conducting a load current to a load and comprising; a silicon-controlled rectifier; a transistor; said silicon-controlled rectifier and said transistor being operatively connected in parallel and the parallel combination of the silicon-controlled rectifier and the transistor being connected in series with the load; a connection between the cathode of the silicon-controlled rectifier and the base of the transistor; and means operatively connected in series with said siliconcontrolled rectifier for turning on said transistor, said means including a resistor, another transistor operatively connected in series with said silicon-controlled rectifier and said resistor and wherein, a power source is operatively connected to the anode of said silicon-controlled rectifier and to the collector of said first mentioned transistor; the cathode of said silicon-controlled rectifier is operatively connected to the base of said first mentioned transistor and to one side of said resistor; the other side of said resistor is operatively connected to the collector of said second mentioned transistor; a control signal device is operatively connected to the gate of said silicon-controlled rectifier and to the base of said second mentioned transistor; and a load is operatively connected to the emitter of said first mentioned transistor and to the emitter of said second mentioned transistor.
Claim 2
Dependent Claim
206 words
A control device for conducting a load current to a load and comprising; a silicon-controlled rectifier; a transistor; said silicon-controlled rectifier and said transistor being operatively connected in parallel and the parallel combination of the silicon-controlled rectifier and the transistor being connected in series with the load; a connection between the cathode of the silicon-controlled rectifier and the base of the transistor; and means operatively connected in series with said siliconcontrolled rectifier for turning on said transistor, said means including a resistor, another transistor operatively connected in series with said silicon-controlled rectifier and said resistor and wherein, a power source is operatively connected to the anode of said silicon-controlled rectifier and to the collector of said first mentioned transistor; the cathode of said silicon-controlled rectifier is operatively connected to the base of said first mentioned transistor and to one side of said resistor; the other side of said resistor is operatively connected to the collector of said second mentioned transistor; a control signal device is operatively connected to the gate of said silicon-controlled rectifier and to the base of said second mentioned transistor; and a load is operatively connected to the emitter of said first mentioned transistor and to the emitter of said second mentioned transistor.