To provide a motor-control circuit, having a motor protection circuit that has a small number of components and a simple configuration, using inexpensive components.
This motor-control circuit is provide with a current detection resistor 4 that is connected in series with a motor 1, a series circuit of an operation switch 5, a switching element 6, and a relay coil 7 that are connected between a power supply and a reference potential point, a bias circuit 8 which includes a temperature-dependent resistor 8A1 for supplying a bias voltage to the switching element 6, a switching state self-retention circuit 11 including an automatic operation switch 14, and an overvoltage detection circuit 10. When the switch 5 is turned on or when the switch 5 and the switch 14 are turned on simultaneously, the switching element 6 is turned on for energizing the relay coil 7, and the motor 1 is driven by the switching of a relay contact 3. When the motor 1 is driven, an overcurrent flows to the current detection resistor 4. When the temperature increase in the current detection resistor 4 is detected by the temperature-dependent 81, and/or the voltage increase between the terminals of the current detection resistor 4 is detected by the overvoltage detection circuit 10, the switching element 6 is turned off through the bias circuit 8 and the drive of the motor 1 is stopped.
TANAKA MASAAKI
NAKATANI HIROAKI
NAGAOKA SHUICHI
TAKAGI ISAO
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