Hello Mark !

> help much. My plan is to use a wire around a spark lead as the sensor with
> a PIC counting the pulses and displaying to two 7-seg displays the Revs
per

I'm in final tests with mine too.
It's a digital tachometer with 5 digits and a bargraph of 14 leds, it also
has a shift light, revolution limiter, max rpm memory, etc.
It's based on 16F872 running at 16Mhz, and it's capable measuring up to
99999 RPM.
For more accuracy I'm measuring the period between the Sparks.
The tacho, itself it's done, and working OK, but ....

Actually, I'm having trouble with the sensor interface ....
The EMP from ignition is generating noise and making impossible to measure
the period of the Sparks ....

BTW.: If someone in the list has any idea for filtering the signal, would be
fine.

> I'll need some form of transformer to take the 12v car battery to a 5v
> regulated circuit for the PIC, any help with all of this would be greatly

Why a transformer ???? Why don't you assign a 7805 for the work ??? I think
that's no problem using a linear regulator, because the current is very low
... (We are talking about PICs remember !)

Thats all ...

Let me know if I could help you  in any way ...

Fabio Pereira
Joinville - SC - Brazil

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