At 13.26 2010.12.30, Rodolfo wrote:
>I you can bend the wire, you can use a rotary encoger, too (using a pulley
>or Wheel).

Problem is that it won't probably fit into a 20mm pipe. :P


>
>-----Mensaje original-----
>De: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] En nombre de
>Rodolfo
>Enviado el: Jueves, 30 de Diciembre de 2010 09:15 a.m.
>Para: 'Microcontroller discussion list - Public.'
>Asunto: RE: [EE] Cheap, thin, 36mm linear encoder with one+ million cycles
>
>I beg your pardon but I=B4m new to this list.
>What about linear potentiometers ?
>
>Cheers
>
>Rodolfo
>
>-----Mensaje original-----
>De: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] En nombre de
>Electron
>Enviado el: Jueves, 30 de Diciembre de 2010 08:58 a.m.
>Para: Microcontroller discussion list - Public.
>Asunto: Re: [EE] Cheap, thin, 36mm linear encoder with one+ million cycles
>
>
>Hello,
>
>At 10.05 2010.12.30, you wrote:
>>> I need to sense the position of a steel wire in a cable (similar to=20
>>> the cables of bicicles' brakes). It can be moved forth and back by 36mm=
..
>>
>>What accuracy / resolution / repeatability,
>
>Not much.. 8 bit would be plenty, even 6 bit would be ok.
>
>
>>temperature range do you need.
>
>-30C +60C would be already very safe.
>
>
>>What power is available if needed.
>
>Little.. say 100 mW maximum.
>
>
>>What manufacturing volume?
>
>100, as a rough estimate. I could think several ways to make a "one off",
>but
>I need a solution to make a small serie (~100 as I wrote).
>
>
>>LVDT?
>
>Too expensive I think, and can get interference I suppose.
>
>
>>Linear single track (or multiple track) gray code encoder?.
>
>Anything that can sense the absolute position (0..36mm) of the cable is ok=
..
>
>Gray code encoders, if cheap enough, usually are rotary (I never saw one
>linear
>at least). Pretty expensive anyway.
>
>It would be ok also if it didn't sense the absolute position, but had some
>sort
>of "zero flag" to reset the sensor at one of the two sides.
>
>
>>Look at digital calipers.
>>In what way do these not meet your need?
>
>Yes, I didn't think of these, although I have had one in my hands days ago=
..
>:o
>Their capacitive technology is interesting. However, do I get ~100 sensors
>at
>Mouser, DigiKey, etc..? Or should I buy the calipers from China and
>catabolize
>them? :P
>
>
>>(That will tell us a lot about what will and won't work).
>
>Well, I'm pretty much contrained on costs, size, available space, etc..
>
>However, a caliper-like sensor, thin and easy to mount, would be wonderful=
..
>
>Does it even exist?
>
>For example, the cheap chinese weight scales are impressive. If I needed O=
NE
>load cell, I would catabolize one of those weight scales. But if I have to
>actually purchase a load cell as a sensor (at Mouser, etc..) I can easily
>see prices 100 times higher or so..
>
>Miracles of mass production? I don't know, but (forgive the off-topic) a
>small
>load cell could be great for some other application I have in mind.. if it
>could
>be found in 100's at a very low price. All load cells I see from catalogue=
s
>cost
>an eye..
>
>Cheers,
>Mario
>
>
>>
>>
>>        Russell
>>
>>
>>.
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