TIM + Racetech Rev counter issue

benny boy · Post by **benny boy** » Fri Sep 11, 2015 9:14 pm

Hi all,

My MJ v3.3.2 is working well on the sprint/hillclimb mini.

I bought a Racetech rev counter to replace my TIM cheapy rev counter (running with the zener diode circuit from the install guide) that was bouncing quite a bit.

I've never been able to get the Racetech working with either the direct tacho out from MJ pin 8, or the zener diode circuit, or an NPN Transistor/resistor circuit that someone suggested on a Licost forum..

Can anyone recommend a fix to get the Racetech working or (if all else fails) a rev counter that works directly from the MJ pin 8 tach output?

Many thanks

Post by **brentp** » Mon Oct 19, 2015 6:48 pm

Hi Benny,

Did you ever get this working? Most modern aftermarket tachometers *should* work with the Megajolt system.

Or, if you want something classic, you can use a old-school Porsche 914 tach. It'll work with the diode circuit with bleed resistors across. (See our TachX module)

EnosBlinn · Post by **EnosBlinn** » Fri Oct 23, 2015 8:18 pm

Can you please specify clearly that what you want to achieve? I mean what circuit you are looking for and for which purpose?
If you already have a circuit then please post a schematic of it also.
Also specify all the components you are using in your circuit?

benny boy · Post by **benny boy** » Thu Oct 29, 2015 1:39 pm

Hi - thanks for the replies.

Ultimately, all I want is a tacho that works (pref with little extra circuitry that might go wrong in future) when I go through scrutineering noise checks!

Because neither rev counters now work :-/ what is the best way to ensure I am getting a good tacho output from the MJ?

(I appreciate an obvious answer is 'a rev counter', but there seem to be so many differing additional circuit solutions for getting differing rev counters to work with MJ)!

My shift light works as it should - that is a different output to the tacho, but I suppose that indicates the MJ unit is getting a good signal to it...

Thanks

Post by **brentp** » Thu Oct 29, 2015 10:30 pm

If you can't get the tach output working on the Megajolt, you can also tap into the coil pack signal using a diode circuit.

http://autosportlabs.net/MJLJ_V4_vehicl ... achometers

You can also use the EDIS-4's IDM signal as an alternative source.

So, about 3 options you can employ in total.

Let us know how it works!