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does anyone kow if the 808 with coil pack will run a kus tacho from the tacho output wire from the coil pack
http://www.ebay.com.au/itm/221578291066 ... EBIDX%3AIT

I'm guessing it wouldn't work.
There isn't much information provided in that ad, but it does mention it's a cross coil type tacho.

If it doesnt you could use a basic circuit like this to make it work.

http://pcmhacking.net/forums/viewtopic. ... lay#p21551

As jayme has stated elsewhere you just want to open up the relay and remove the relay bar so it doesnt buzz. You just need the coil charging and collapsing to give you the right signal for a traditional tacho.

found this board on a smiths tacho I had converted ( by Auto Cooling and Instruments) to run off the coil pack 12 years ago (would this be same principle as your simple circuit)

It might amount to the same thing, but thats not working the same way. It has an amp there so must be using that to create a bigger voltage swing for the tach instead of a real (but small) relay coil.

That's a frequency to voltage converter board - from what I can tell it would need to hook directly in to the meter movement on your tacho and be calibrated, rather than just installed in-line with the tacho signal like the relay circuit. I't effectively using your tacho gauge as a voltmeter instead of a frequency counter.

My speedo corrector also works as a hall effect to VR converter - the AC pulses it creates are nowhere near what a coil negative would see but I might see if it'e enough to trigger my old points tachos anyway....

Festy I think your right posted another pic of hook up
red, ign +12v
yellow, tach signal
blue, + to coil
green, - to coil
black, earth
the question is would it work on the KUS tacho

It would work on a multimeter
I think the first problem with the KUS tacho will be that's it's sealed - and also you'd lose the hour meter function.
If it uses a traditional moving coil for the gauge then you'd need to open it up and remove everything except the coil mechanism.
If it uses a stepper motor for the meter movement, then no it will not work at all.

I beileve it is astepper motor so it looks like using the circuit Antus sugested

Try the relay coil trick, have used it heaps and very rare it does not work. Have had the odd tach that would still not read at high RPM, but wasnt many.