I am trying to make a device to run a DC motor based on the output from a light sensor. The sensor has an npn transistor output that is turned on when the sensor sees no light and off when the sensor detects light. I would like the motor to turn off when the sensor output turns off but I want to manually start the motor (regardless of what the sensor outputs) with an off-momentary on switch. I am using a 12v power supply and the motor is a brushed 12V DC gear motor. It has a rated current of 0.6 amps. It should not be necessary to use a speed control with the motor. The motor would typically turn on / off every 5 or 10 seconds. I was thinking I could use a MOSFET to power the motor although perhaps there is a reason to use a relay. I am fairly new to electronic design and would appreciate any help in getting this to work.