Hi all,

I want to build an rpm meter for my car with an acoustical rev limit signal.
I have heard that you could quite easily extract the engine's rpm from the
AC component riding on the DC of the cigarette lighter plug/outlet. As a
matter of fact, there are some commercially available aftermarket in-car
display units which can do the same from the DC outlet. However, these units
are too extensive for my application.

Has anybody have any experience with this kind of application?

Is it just a matter of AC coupling the car outlet's ripple to some kind of
comparator before feeding it to the PIC for further processing? Or is there
a more advanced technique necessary like an FFT?

Thanks!

Daniel...

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body