what is in a time percentage dial controller?

[coppercone2]

My kiln had this tech before the retrofit. It is a misc box that has a dial on it which you set so it works like a sort of PWM circuit with a fixed frequency (low)

I thought it was electronic at first with something like a RC circuit and a relay but I suspect that it might be mechanical.

Its not a thermostat because you could hear it click based on the settings and it was not connected to the kiln temperature sensor.

How do these work? Or is there a RC circuit in there?

I don't know where it is anymore. Maybe thrown out. I have PID on it now. And this one is like from the 70's

[reodor]

It could be something similar to a simmerstat. It is like a thermostat, but the thermal sensing comes from a separate, low power, heating element. When the switch is on, the heating is on. The tension on the bimetallic element determines how long it takes before it gets hot enough to turn off again.

The Youtube channel "Technology Connections" has a video about them:

[DaJMasta]

If it really is a time interval based thing with no feedback, it could work like a simple mechanical timer - a continuous source of motion that slowly rotates and switches when past the dialed in location.  You could do the same electronically and easily, it's basically pwm as you say but where the base resolution is on the order of seconds or more and a complete turn of the dial is a single period.

[coppercone2]

So you think it can be a motor? I was starting to think thermomechanical oscillator. Its too light for a motor. I recall it was really light. must be the same as the video IMO

[Zero999]

So you think it can be a motor? I was starting to think thermomechanical oscillator. Its too light for a motor. I recall it was really light. must be the same as the video IMO

I encountered a similar device in an old microwave oven. It's a cam timer activating a switch. Why do you think it's too light to be a motor? There are very small motors, such as those used in clocks. The winding is similar to a relay.