Another thing about contacts: Some level of current must be carried through mechanical contacts to prevent buildup of oxide or other contaminants which will eventually inhibit conductivity. If memory

They didn't have Silicon diodes in Strowger days, only Selenium, which devices were leaky and bulky. R/C was the appropriate tech. Now, Si.

Use diodes! Unless I've missed something earlier in the thread, quenching diodes will solve any sparking problems. In early days, rectifiers were either in vac. tubes or made up of stacked plates of S

I don't think this is your page. What is yous, I'd like to have a look at the code / thanks!

In your code the following is confusing: TCCR1B = _BV(CS10) | // start Timer 1, no prescaler _BV(ICES1); // Input Capture Edge Select (1=Rising, 0=Falling) is there a term missing? thanks /mark