non-DFI tach question

Tom Parker parkert at ihug.co.nz
Tue Nov 2 12:52:04 GMT 1999


Unknown <brucep at ptd.net> wrote:

>drop of the ground when the points open. Could I use parts from a GM 4
>cylinder HEI coil ie: coil pickup and ignition module.I think I am headed
>in the right direction just need some advice on different ways I could do
>this.

Anything that has 2 pulses per revolution (for four cyclinder four cycle
tachometer) should do the trick. A cam and good old points even.

>Ideally I would like to have a digital display which would allow me to
>have a more realistic reading of rpm's as opposed to well it looks like it
>is 2000 not 2010, 2020 or 2050. Any help would be greatly appreciated. And
>sorry for taking up bandwidth for the non-dfi post but this was my last
>place to ask . . . thanks in advance.

Have a look at frequency to voltage converters. Don't know who makes them, but
it shouldn't take long to find a datasheet. I'm not sure how accurate they can
be, but you should be able to hook one up with a multimeter as a display, or
use the movement in the tach if it is accurate enough.

A friend of mine put such a circuit into his misbehaving period tach. Looks
completely original from the outside, but reads far more accuratly.

Also, someone else was wondering how to connect a 6 cyclinder tach to a 4
cyclinder engine (or the reverse). You could use a freq->volt and then a
voltage to frequency (voltage controlled oscilator??) with an aproprate
divider between them. Just a thought, no idea if it is feasable..

--
Tom Parker - parkert at ihug.co.nz
           - http://www.geocities.com/MotorCity/Track/8381/




More information about the Diy_efi mailing list