Replacing simple mechanics with electricity and electronics.

My Adler class 8 sewing machine was built for speed. It can sew faster than I can handle it when working with light materials. It is just about manageable when sewing heavier stuff like the leather it was bought to sew, but it does bog down sometimes. It also can’t sew at really low speeds - I need to slow step things when sewing decorations on the leather do-dads I make, and that’s just not possible,

If I had the original treadle table that it was installed in when new, it’d be easy - I’d just have to learn to work the treadle at low speed.

The treadle is long gone, though, due to the fad here in Germany of making garden tables out of sewing machine tables.

My Adler has an electric motor and a crummy foot pedal control.

This series of posts is about concepts in motor speed control and designing a controller that meets my needs.

  1. A sewing machine motor speed controller - Musings on motor speed control for universal motors - Ideas for taming my Adler.
  2. A sewing machine motor speed controller - Basic ideas on how not to make a motor speed control - Simple but not really useful.
  3. A sewing machine motor speed control - A MOSFET source follower as a motor speed control- Better, but far from good.
  4. A sewing machine motor speed control - A simple pulse width modulation driver as a motor speed control - One step forward and one step back.
  5. A sewing machine motor speed control - A pulse width modulation driver with feedback as a motor speed control - Moving forwards again.
  6. A sewing machine motor speed control - A pulse width modulation driver with PID as a motor speed control - Getting closer.
  7. A sewing machine motor speed control - PWM + PID + current measured BEMF = Fail - A failure and a new plan.
  8. A sewing machine motor speed control - Using a photointerrupter for speed control feedback - Works about as well as could be hoped for.