Frequency to Voltage Conversion- Thanks

[BigBrother at mail.utexas.edu]

> (Dan Bocek writes)
>
> While it is true that some airflow measuring techniques have a frequency
> output (the Karmen-vortex sensor, as used on a lot of Mitsubishi cars,
> comes to mind, although its output is pulse width modulated, so all you
> have to do is low pass filter the output to get DC) I've never heard of
> a MAP sensor outputting AC.  Where did you get this info?


I found out that MAP and BP sensors (at least Ford) output frequency
instead of DC voltage from a Ford EFI book.  Of course most new Ford's
don't use the MAP (or BP as it is called now) to measure mass air.  They
just use a MAP sensor hooked up to nothing to measure barometeric
pressure.  That is why it has been renamed the 'BP' sensor.  Mass air
sensing comes from a hot-wire type MAF sensor.

Anyway, thanks to everybody for the pointers on frequency sampling
techniques.  If I wasn't forced to take so many b.s. classes before
the real EE stuff, I wouldn't have to ask!