Uaefi tachometer setup explained

[jasaircraft]

Hello guys
So as documentation and also to get some help setting up the tachometer signal, could we have a brief explanation what the variables are for?

In my case i want to drive a oem honda 92 tachometer.
Thanks

[jmhalder]

I have a similar problem, I have a '97 Toyota Camry. It worked fine with a pulsed 12v output from my Microsquirt.

As far as I can tell, there isn't a 12v pulsed output to use on the UAEFI. It was suggested to use a ignition output for the tach, and... it sorta works for ~1 second when I first start the car. Then the needle falls to 0rpm and stay there regardless of revving it.

I've read elsewhere that I can use a injector output with a pull-up resistor to 12v. I'm not sure where to pull 12v from, or what value resistor to use. The documentation has zero information on tach output wiring.

[AndreyB]

there is "prototyping are" in the middle of uaEFI but does not look like it has +12v

power supply area has a couple of vias with +12v.

[jmhalder]

What pull-up resistance would be okay to use on a injector output? I assume a 10k resistor would be fine. 4.7k if the 10k doesn't work? I assume this would function as "default inverted" but am having a hard time understanding that as well.

[Wombat]

For Hondas that used to have distributors i used a single 2n2222 or bc547/9 transistor, with a 1k resistor from 12v to the collector and a 1k base resistor.
The collector goes to ground and your tacho signal wire connects to the transistor collector.

I dont have my uaEFI yet to check but you might be able to use one of the low side relay outputs with a pullup resistor to 12V to do the same thing...
I need to find this out myself because I will need a 12V tach output for my Civic.