MAX232 and RPM

[Peter Gargano]

BILL.ZAFFOS at chase.com wrote:
> 
> Peter,
> 
> Have you done anything using the MAX232 with an inductance loop to check RPM?

No, but it's an interesting idea! Using the 160 baud input you could display
things like dwell and RPM - just need some software! Could connect to points
circuit for a signal more easily.

> I have some older GM cars without computers and I was thinking that with this chip
> and an inductance loop, I could display engine RPMs by attaching the loop to a
> spark plug wire.  

An inductance loop or capacitive pickup would require some extra circuitry
to ensure the PC didn't get zapped, or that it got a strong enough signal
to make it all work. The 160 baud input is just looking to see if a signal is
either ON or OFF. But this isn't as limiting as it sounds...

> I was hoping that you have tried this and could steer me in
> the right direction as far as additional electronics are concerned.  I have the
> desire to do stuff with computers and electronics but not the knowledge.

I have the same desire, but not too much time at present!

> 
> Any help will be appreciated.

I won't promise anything, but perhaps someone else has an idea about software?

-- 
Peter Gargano