This 220VAC motor speed controller Circuit can handle brushed AC motors and other loads up to about 250W.It works the same was a dimmer circuit, cutting a portion of the AC waveform is seeking to effectively control the tension. Because of this feature will work cycle for a wide variety of loads including incandescent bulbs, heaters, brushed AC motors and transformers. The circuit attempts to maintain a constant engine speed regardless of load, it is also ideal for power tools. Note that the circuit can only control brushed AC motors. Inductive motors require a variable frequency control.
- TR1 must be chosen to match the requirements of the load. Most generic TRIACs with ratings to support your load will work fine in this circuit.
- U1 must be chosen to match the ratings of TR1. Most generic DIAC based opto-isolators will work fine
- T1 is any small transformer with a 1:10 turns ratio. The circuit is designed to run on 120V so a 120V to 12V transformer will work. Alternately, you can wind T1 on a transformer core using a primary of 25 turns, a secondary of 200 turns, and 26 gauge magnet wire.
- R9 is used to adjust motor speed. R10 is a trim pot used to fine tune the governing action of the circuit. R8 fine tunes the feedback circuit to adjust for proper voltage at the gate of SCR1. It should be adjusted to just past the minimum point at which the circuit begins to operate.
- R13 must be chosen to match the load. Generally, larger loads will require a smaller value.
R1 : 27K 1W Resistor R2 : 10K 1/4W Resistor R3 : 100K 1/4W Resistor R4 : 33K 1/4W Resistor R5 : 2.2K 1/4W Resistor R6 : 1K 1/4W Resistor R7 : 60K 1/4W Resistor R8 : 3K Trim Pot R9 : 5K Taper Pot R10 : 4.7K Trim Pot R11 : 3.3K 1/4W Resistor R12 : 100 Ohm 1/4W Resistor R13 : 47 Ohm 1W Resistor (See Notes) C1,C3 : 0.1uF Ceramic Capacitor C2 : 100uF/50V D1 : 6V Zener Diode Q1 : 2N2222  SCR1 : ECG5400 TR1 : TRIAC (See Notes) U1 : DIAC Opto-Isolator (See Notes) BR1,BR2 : 5A Bridge Rectifier T1 : Transformer (See Notes)