I can tell you where to start.
The motor speed control uses triacs to remove parts of a sine wave.
The more parts of the sine wave that are removed the slower the motor
turns. By removing just parts of the sine wave the frequency and the
amplitude still remains the same. Therefore the motor dose not over
heat.
You will need to build a variable oscilator controlled by your foot
pedel. This osclator will need to turn on and off a triac multiple
times at varing pulse withs while staying in sync with the 0 volt
crossover point of the AC sine wave.
This month Nuts & Volts magizine started a tutrial on triacs.
It covered the basics of triac control.
Next month will be the second part going into more detail.
This could be a good start to design your own.
Nuts & Volts magizine www.nutsvolts.com
Good Luck
Mike Casino
--- In hammond_zone@y..., "daphobang" <daphobang@y...> wrote:
I would like to know if anyone can help me design a motor speed
control switch that acts as an expression pedal (speeds up as pedal
is pressed, slows down as pedal is depressed)rather than just
on/off
switching. Thanks
