Surely not another Tacho question.....

[fsmlittler]

O.k. no surprise that my Tacho doesn't work on my newly installed set up. Everything else is fine but the Tacho output doesn't drive my Stack Tacho. Having spent hours reading all the threads I could find I seem to have reached the conclusion that it needs running off the negative side of the coil but the need for the diode circuit is caused by the coil pack having two coils. If you're still following me here how about this plan...my tacho is switcheable from 1 cylinder to 12 so my guess is that if I take a feed from either of the two coil negatives to the Tacho and set it for 2 cylinder running it should read correctly (or is it 8cylinder I need?). Should point out it's a 4 cylinder engine.

Also may have already been asked but since this is such a common problem has anybody thought to produce a list of Tachos that will work off the Tacho output?

Thanks for staying awake.

Chris

[brentp]

Are you running V3 or V4? V4 has a 12V square wave that's closer to a 50% duty cycle than V3.

Yes, 2 cylinder setup should work for you; you can avoid building the diode circuit.

[fsmlittler]

Thanks Brent.
It's version 3.2.0. although the bit about the square wave and duty cycle is too technical for me! If I can run the tacho on 2 cylinder mode do I need any kind of resistor in line or will that be trial and error?
Chris

[brentp]

If your Stack gauge is designed to work off of the (-) terminal of the coil, then it should 'just work' by wiring it to one of the coil packs- but, of course, refer to that system's documentation.

The bit about duty-cycle is that we simply improved the design of the TACH_OUT on V4 to make it more compatible with different devices (tachometers, ECUs, etc).