AVR-Chat

Using a pot like this, especially a wire wound, 10 turn type, could be 
bad jazz.  I tried that once on a dancer arm for a textile finishing 
line to gather data.  It didn't last very long.

If cost is an issue, David, have you ever thought about making your own 
LVDT?  The L might not be very good, but it would be repeatable.  A coil 
of wire is cheap.  In a pinch the coil from an old reed relay can be 
used.  A steel rod can easily be fixed to your fork and as it extends 
and retracts into the coil it would change the frequency of an 
oscillator.  Frequency is easy to measure.

It would take some experimentation to develop a cheat sheet, I mean, a 
correction curve, for your DIY LVDT but that can also be done fairly easily.

How about a couple of linear bearings on the rod to ensure it doesn't 
flap too much?  Those aren't too expensive either.  You would probably 
need some similar mechanism for the more expensive LVDT, anyway.


REB



Darren Worley wrote:
>>> Measure the travel of *this* wheel: http://home.
>>>       
> <http://home.hiwaay.net/~dkelly/Husaberg/Pages/4.html>
> hiwaay.net/~dkelly/Husaberg/Pages/4.html
>
>   
>> No problem - add a reluctance pickup, near the chain, on the front of the
>>     
> drive sprocket. 
>
> I think meant how far the wheel moves up and down in relation to the frame.
> Is this for the rear wheel?
>
> LVDT? or Something simpler -> Concept: mount a 10 turn linear pot with a
> negator spring and small deep section pulley directly attached to the pot
> spindle. Wrap 10x with fishing line all sealed in a rubber casing that has a
> tiny hole for the fishing line to escape as the actuator. Depending on your
> pulley circumference (x10), depends on linear distance measurable. Wind the
> pot fully anticlockwise, connect spring, then wrap the line around the
> pulley clockwise. The negator spring is a constant force spring and as you
> pull the fishing line it tightens up and applies constant force on the line,
> and the distance moved is then a linear resistance measurement. Mount the
> module above the rear plastic guard, (secondary protection against direct
> mud/stone spray, and gravity works to your favour to some degree) but keep
> close to the frame then drill tiny hole/slot through guard, seal with second
> piece of rubber, pull fishing line though and attach to the swingarm via
> swivel, but closer to the pivot point to keep away from potential sticks
> etc. Any mud that collects on the string will be wiped of by the rubber
> seals (similar to the front shock seals). This method may be prone to
> sticks/stones/sticky mud/ though, but is ultra cheap and easy to do. I'd be
> interested if you actually do this.
>
>   
>


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