It's been a while since I've done a post. I'm still active, but I've been busy with a lot of things as of late.

Anyways, something that I've wanted to see the inner workings of, was an old sewing machine foot pedal that's been lying around. It's a bit older than me. On to the exterior photos:

As you can see, it's a bit on the crusty side, with some electrical tape as a bonus, safety third!

Time to get into the pedal.  The back slides off, but a screwdriver is needed as leverage to get it off.  Oxidation made it challenging.

Inside it's obvious (and along the lines of what I expected to find) what it is, a variable resistor with  8 fixed positions (including a shorted position and the "off" position.) The resistor is composted of segments of coiled wire and contact points for the wiper that's wrapped around a piece of ceramic.  End to end, the resistor is around 100 or so ohms. 

The resistor isn't very accurate or precise (not that it needs to be) and resistance can greatly change if you look at it the wrong way (connections between the coiled wire and contact points are quite finicky.)

This thing is very much "safety third!" There's two large potential hazards. There's no grommet to prevent the wires going in from being nicked (although it may have had one that perhaps crumbled away.) The second big hazard is that the metal housing isn't grounded. If one of the coiled wire segments were to break or pop off, it could make contact with the housing, potentially making the housing itself live.  It wouldn't pass safety standards today.

I also have the sewing machine this foot pedal goes with, perhaps I'll do a teardown of it in the future.