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Megasquirt and Tacho driving - opinions please
adrianreeve - 26/3/11 at 07:00 AM

As far as I can see, there are two ways of driving a traditional coil driven tachometer if you have megasquirt:

1. Use the tacho output from the 'squirt, and add a relay coil in line to provide a voltage spike (as per extra efi website)

2. Use a tacho driver made of 3 diodes to directly drive the tacho from the coil pack, no connection to the megasquirt required. (Trigger wheels sell one for £10)

Which method have you chaps used / would you recommend?

Thanks

Adrian

snapper - 26/3/11 at 07:17 AM

I have used the 3 diodes off a coil pack, this worked without issue.
I have used the Tacho out from the EDIS no problems.
I am now using Megajolt Tacho out on a Smiths electronic

matt_gsxr - 26/3/11 at 07:43 AM

I have a coil (like the relay solution) driven from the low tension side (just one ignition output on my wasted spark system). This gives the right number of pulses for my Aprilia rev counter.

I set it up this way as previously I was using the stock suzuki CDI, and haven't changed it.

SPYDER - 26/3/11 at 01:56 PM

I used method one. No problems.

scudderfish - 26/3/11 at 05:07 PM

I used the relay method, but the buzzing annoyed me as the relay was behind the dash and not in the engine bay. I now drive my tacho off my EDIS module.

paulf - 26/3/11 at 10:01 PM

If you have an Edis then the pip signal sometimes works better than the tacho output on some rev counters, i have mine connected up like this and the smiths type tacho works reliably .
Paul

adrianreeve - 27/3/11 at 02:44 PM

No edis, so I think I may go for the diode option.

Cheers

Adrian

scudderfish - 27/3/11 at 04:11 PM

My tacho just packed up Time to fiddle with the wiring again....

DaveFJ - 28/3/11 at 12:18 PM

i went for the diode option.. a few cheap parts from maplins and a few mins with a soldering iron - jobs a good'n

austin man - 31/3/11 at 08:45 PM

quote:
Originally posted by DaveFJ
i went for the diode option.. a few cheap parts from maplins and a few mins with a soldering iron - jobs a good'n



any chance of a diagram and detail of parts I have an acewell with Tacho which reads a little sporadic and a seperate 52 mm gauge which reads wrongly so im going to have to do someting. I have megajolt and EDIS fitted

Snuggs - 3/4/11 at 10:36 AM

quote:
Originally posted by austin man
quote:
Originally posted by DaveFJ
i went for the diode option.. a few cheap parts from maplins and a few mins with a soldering iron - jobs a good'n



any chance of a diagram and detail of parts I have an acewell with Tacho which reads a little sporadic and a seperate 52 mm gauge which reads wrongly so im going to have to do someting. I have megajolt and EDIS fitted




Megajolt has a Tach Out that normally works.






U have U2U


Clive