The standard circuit to multiply a frequency is a phased locked loop and there are ICs that implement it. If I recall correctly they don't handle varying frequency well.

Quote Originally Posted by stirling View Post
When you pulled the drill trigger, you might just as well have turned a pot.

The MPG is just becoming a distraction. Everything that everyone has suggested (even Irving with the ONE pulse per rev) is battling against the MPG's natural behavior.
Not everyone - I suggested the pot. back in post #13... However Jazz said he 'would like to keep the detent control of MPG', i.e. be able to move a distance specified by turning the dial, not just set it at a speed and go. Either are easy to do with a microcontroller. The differential signalling very slightly complicates matters. I just suggested Arduino as although I dislike them, it's undeniably easy, but in post #14 Jazz seems to call that a 'massive electronics project'...

In software it is trivial - just stay one pulse behind, measure time (t) between pulses and output pulses at f=n/t where n is 10,20,50. If another pulse not received, output n pulses at your favorite frequency to catch up. But as Irving pointed out 'Dean wanted a learning experience too'.

Quote Originally Posted by JAZZCNC View Post
To be honest I'm little surprised( slightly dissapointed) there are not more takers or more informed/detailed suggestions because I know there are plenty on here who do know how or could easily come up with something.!
It's more entertaining to watch and see what other people come up with. Plus I'm busy at the moment with another massive electronics project , so you'll hear from me if this isn't over in a month or two.