Make a Mechanical Timer: Spring vs Counterweight

[Kaycee92]

Hi,

I am thinking of making a mechanical timer to control a pedestal fan.

I want do a completely mechanical one, just for the feel of it.

For the energy storage method, I have two options, either a spiral spring or a counterweight. Which one should I use? Any good reading material on this?

I can take care of gearing. The fan's plug is connected to a 3 pin socket beside the switch. How do I cut off the supply (turn off the switch) when the timer stops?

Thanks,
Chaitanya.

 

[OldEngr63]

A gravity drive (weight) will generally require that the system not be portable at all as the gravity drive requires a long fall from a fixed point. A spring drive is compact, not much disturbed by being moved around, and generally provides more flexibility in the application. The gravity drive is somewhat more precise than the spring drive, but that probably is not an issue here.

You can find lever mechanisms that will simply come out to push the existing switch at the appointed time to turn the fan off, so that is a simple solutionsing the existing switch.