Hi audioguru,
1.) Not grumpy at all
2) The comment was not directed at you!
Forums are by and large a community of goodwil! Pllease and thank-you are things called MANNERS and are appreciated by people who give up there time.
With reference my design - complicated - I couldn't agree more (it wasn't intending to be when I started thinking about it!!!
But it might give the original poster an idea on how to produce his (or her) own work to solve a problem instead of abitarily reproducing someone elses.
But the circuit would solve a number of 'issues' (if it worked
) frequency drift, component values, interfacing with ignition etc it would also allow for complete 'tweaking' of 'red line' values not to mention the possibility pending red line approaching and offer machine and cylinder number independancy (sorry for bad english).
It would also allow for an easy project to work on and fault find espeacially if your new to electronics. But as a stevez said this would be ideal for a MCU based project.
Being a biker myself I can think of three reasons why mattpatt was after an RPM switch - Racing, Tweaked engine ( :wink: ) or an interesting project. If it is the one of the first two he (she) needs reproducable accuracy.
With refernce to the diagram I'm not completly sure how to show the diagram properly, and as I have noway of deleting the post after I sent it I erred on the side of caution.
A non grumpy Dotnet Signing off