เครื่องปรับรอบมอเตอร์ PWM Motor controlCircuit Description The PIC12F683, IC1 has an internal hardware PWM peripheral that is used to generate the PWM signal. The duty cycle of the PWM signal is controlled by VR1 which via R1 presents a voltage on pin 3 of IC1. With 0V on the input the duty cycle is 0% (off) up to 100% with 5 volts at the input. The PWM signal is output from pin 5 of IC1 and drives the gate terminal of Q1 through R3. Resistor R4 connects the gate terminal of Q1 to ground. This ensures that Q1 remains off when the circuit is first powered on as the I/O pins of IC1 are all set to inputs until the firmware initialises them as outputs. Diode D1 is required when driving inductive loads and provides a path for the inductive flyback current. For loads up to 3 amps Q1 does not require a heatsink, above this you may need to use one.