AC Motor Speed Controller
Build an AC 220V fan speed controller using a triac and a diac. Easy, efficient, and safe circuit for adjusting ceiling or table fan speed.
AC fan speed controller circuit
The AC 220 V fan speed controller is designed as a triac–diac phase control device to adjust the voltage to the motor to give an efficient fan adjustment in speed, without any unnecessary heat loss.
ceiling fan speed controller
One of the applications is to use an AC 220 V fan speed controller to control the speed of a ceiling or table fan by varying the AC supply to the motor. In this circuit, a combination of a triac and a diac is used and operates on phase-angle control to control the supplied RMS voltage to the fan. This electronic design is more cost-effective, compact, and less wasteful of energy as compared to conventional resistive regulators that consume energy in the form of heat. The speed of the fan is regulated by adjusting the firing angle of the triac by using a variable resistor (potentiometer). In case of a delay in the firing angle, less power is applied to the fan, and the speed is slowed. As the angle is increased, the voltage fed to the fan increases, and the speed increases.
This is a safe and reliable controller commonly used in contemporary fan regulators. Nevertheless, it is driven by induction-type ceiling fans.
Work / Installation (Inputs → Outputs)
- Connect the 220V AC input to the regulator circuit.
- The diac triggers the triac based on the potentiometer setting.
- The triac controls the conduction angle, adjusting the fan’s input voltage.
- Output delivers variable voltage, controlling fan speed smoothly.
Testing & Final Adjustments
Upon completion, attach the controller to a ceiling or table fan. To start the test in a safe manner, set the potentiometer low and begin testing. Measure the RMS output voltage using a multimeter, and you will see that it will change as you change the knob. When the fan hums too much or stops, modify the component values (resistor/capacitor) to optimize performance. To be sure, the triac should have a heat sink to be reliable over time. Always use a safe, insulated configuration to prevent shocks of electricity. The circuit is now ready to be used on a daily basis once it has been established that it is stable.
