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Driving analog rev counter from spark plug wire

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Moderators: Curt!, Pa

Posts: 48
Here's a challenge for the electronical wizards.

For my 45" with magneto ignition I want to install an electronic analog rev counter.

The only signal source I can think of on my bike is the spark plug wire (there's no battery, timer or coil). The signal wire is then wrapped several times around the spark plug wire (so called inductive signal).

I have only seen digital rev counters making use of such inductive input (see picture 1). But I want an analog rev counter like the MMB in picture 2. Also want to avoid a mechanical driven tacho.

So... is it possible to convert the inductive signal to the signal the MMB electronic tacho can use? Or is there any another trick I can use?
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Posts: 199
Location: Cedar Springs Mi USA


There is already a commercially available one that is popular amongst racers, it is a "Scitsu" made in England.
It feeds off a spark plug wire lead, and is a 3" dia face analog dial tach. It has an internal rechargable battery that is good for 10-12 hrs of use. Pretty pricey too.

I'm not crazy about the one I have, cuz over 4K it seems to lose it's mind.......never consistent, or believable.

The digital ones are a little hard to read.........unsafe, at speed when you're needing to watch where yer going, and worried about your red line at the same time.

Posts: 48
Thanks fabercycle, just the information I was looking for!
Piet Jan (two words, one first name)

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