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AC motor speed controller kit - K2636

by Welleman

Universal AC motor speed controller kit

This kit was designed to control the speed of AC motors with carbon brushes, anything from drills to saws to vacuum cleaners. Unlike other circuits such as normal dimmers the kit performs a phase cut only once per period. The moment of cutting determines the speed, which can be adjusted from 5% to 95%.

The kit provides high torque even at low speeds. RFI is suppressed to eliminate noise and interference. The circuit controls both low voltage (from 24VAC to 240VAC at 5.5A) AC motors and mains voltage (110VAC or 220VAC) loads.

The supply and load circuits are electrically isolated from each other for safety and reliability. The control circuit is powered by the mains, but the load supply may be derived from a different AC source. Both voltages should be the same frequency and the same phase or opposite phase.

Parts list:

  • R1: 4.7K resistor
  • R2: 3.3K resistor
  • R3: 680 ohm resistor
  • R4, R5: 22K resistors
  • R6: 1.5K resistor
  • R7: 47K (50Hz), 10K (60Hz)
  • R8: 100K resistor
  • R9: 100 ohm resistor
  • R10: 120 ohm resistor
  • R11: 68 ohm resistor
  • R12: 1K resistor
  • R13: 27 ohm resistor
  • R14: 390K resistor
  • RV1, RV2: 100K trim potentiometers
  • C1: 470uF electrolytic capacitor
  • C2: 1uF electrolytic capacitor
  • C3: 100nF capacitor
  • C5: 47nF capacitor
  • C6: 100nF/400V capacitor
  • C7: 47nF/400V capacitor
  • D1, D2, D7: 1N4007 diodes
  • D3-D6: 1N4148 diodes
  • T1-T3: BC547B transistors
  • T4: BC517 transistor
  • TRI1: BT137F-600 Triac
  • F1: 250mA slow fuse
  • F2: 5A slow fuse
  • L1: 50uH/1kHz coil
  • Trafo1: 2x6V/1x0.3A
  • Heatsink for the triac
  • terminal blocks (VAC, load and mains)
  • J1, J2 mains voltage jumpers
  • printed circuit board
AC motor speed controller schematic diagram

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