Blue/white tach wire signal voltage?

[jimwildman]

was there supposed to be a picture in that post?

[ChrisWNY]

For the previous post? Yes, there are 2 photos there...if you connect to the Internet via a proxy, etc., there's a slight chance those images are being blocked since I posted them using a free image hosting service.

[jimwildman]

Originally Posted by ChrisWNY

For the previous post? Yes, there are 2 photos there...if you connect to the Internet via a proxy, etc., there's a slight chance those images are being blocked since I posted them using a free image hosting service.

yep now that im at home im seeing them.
whoa!
Well we know it can take 12v on the signal wire without damage.

[ChrisWNY]

Originally Posted by jimwildman

yep now that im at home im seeing them.
whoa!
Well we know it can take 12v on the signal wire without damage.

Yeah I was kinda surprised the tach wasn't at least showing some weird behavior with 12V going into it. You'd think it would've lit up a little brighter.

[jimwildman]

Originally Posted by ChrisWNY

Yeah I was kinda surprised the tach wasn't at least showing some weird behavior with 12V going into it. You'd think it would've lit up a little brighter.

It has to be protected;

I attached the blue and white wire to a charging leg "pre regulator" through a diode and the tach fires right up, its reading x2 though, I believe because there are 2 charging pulses per ignition pulse.

What that tells us is the tach will trigger at varying voltages. I tested the charge tap first and saw a big range from 3-5volts up to say 17v ac. Thay have to consider inductive kick and the like with rpm gauges.

When I build my first FI Computer "megasquirt 1" for my 69 spider I used a zeener diode to protect the circutry from the inductive kick of the old school direct connect to coil. Something like that would be cheap insurance for a tachometer.

Anyone know if the cluster can be configured for different cylinder counts? Id love to get the tach in line with the actual rpm.