# Tach Signal Generation



## Tesseract (Sep 27, 2008)

PeterH said:


> ...Question: Is it practical to consider drilling a hole in the adapter plate for a pick-up sensor and then having 4 magnets embedded in the back of the flywheel by my machine shop?


A qualified yes, though I wouldn't use magnets since Hall effect sensors (the kind most frequently used to detect magnetism, that is) might be fooled by the leaking magnetic fields from the motor. Use an inductive proximity sensor which can sense any difference in metal instead. E.g., if the flywheel is steel then you might embed brass bolts or rod stock for the prox to target.



PeterH said:


> I also suggested 4 magnets because I think the Soliton Jr. likes 4 pulses per rotation... I've no idea what the original tach in the donor likes.


1 or 2 pulses per revolution would be better, actually, especially if the electrical noise level is really high (filtering is done in hardware AND software). Putting a clamp on ferrite on the cable to the prox can help, too.

The Soliton controllers can output a signal to the original tach with a different number of pulses per revolution from the prox. A handy little feature, that.


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## PeterH (Mar 20, 2009)

Ok, thanks for that feedback... it is very encouraging! 

I'm guessing I'd want at least two spots of brass or a different metal in the flywheel, just for balance purposes... I'll let my machinist help with that decision. He balances flywheels all the time.

I'll be sure to follow this thread up with the final results just so this is a complete thread, in case someone else faces the same problem.

Thanks!
Peter H.


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## Yabert (Feb 7, 2010)

I also currently work on this tach detection for my car. 
I would cut two empty space on my motor/tranmission connection plate.

I have find a sweet Omron E2E inductive prox at work. Where do you think buy your prox? I saw many prox at less than 10$ on ebay, but I'm not sure about the quality issue.


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## dtbaker (Jan 5, 2008)

I am also interested in following up on this for my next build... The Swift doesn't even have a tach to display to (I use stickers marking calculated 'redlines' for each gear) but I would like to input a tach signal to the planned Soliton Jr to use the over-rpm control feature.

I do not have a tailshaft on the ADC 8", nor is there really room for one in the Swift. so I was thinking that as long as I am considering removing starter gear and lightening flywheel, the way to go might be to drill and tap in 2 or 4 bolts prior to re-blanacing and put a hole in the tranny housing to mount a prox sensor.

Other option I was thinking about is whether there is any chance of using the motor fan blades themselves by peeking in the exhaust side at the fan blade tips with the prox sensor? I guess that is too many pulses though....

Any specifics on 'best practice', or source for decent sensor would be appreciated...


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## Tesseract (Sep 27, 2008)

dtbaker said:


> ..Other option I was thinking about is whether there is any chance of using the motor fan blades themselves by peeking in the exhaust side at the fan blade tips with the prox sensor? I guess that is too many pulses though....


Way too many. I highly recommend using 1 or 2 pulses per turn for the Soliton controllers.



dtbaker said:


> Any specifics on 'best practice', or source for decent sensor would be appreciated...


This is definitely a Frequently Asked Question, so I made a FAQ entry for it on our website under Support\Installation:

http://www.evnetics.com/index.php/support/FAQ/Installation/1#Installation


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## dtbaker (Jan 5, 2008)

Tesseract said:


> Way too many. I highly recommend using 1 or 2 pulses per turn for the Soliton controllers.
> 
> 
> 
> ...



excellent info on the prox sensors themselves.... your 'dealers' should be sure to stock such items as value-added options!

next question, which doesn't fit everyone, is what the easiest mounting location/method *probably* is for people not having a tailshaft. knocking teeth off the starter ring gear and putting a hole in the tranny housing? removing the starter gear completely and adding 2 or 4 bolts with heads sticking up?


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