Sensor for linear distance

[techhelpbb]

J

Originally Posted by asid61

The string encoder allows one to skip a lot of custom work and sense the distance directly, rather than going through extra layers like decoding encoder outputs. Not to mention that given the costs of shafts, bearings, machining, and the encoder itself, it might make more sense just to use the string pot.

Here are some cheap encoders:

Up to 256PPR:
http://www.grayhill.com/products/optical-encoders/

Up to 1000PPR:
http://m.ebay.com/itm/Allen-Bradley-...047?nav=SEARCH

2000PPR (put buffer on transistor output to get TTL):
http://m.ebay.com/itm/New-in-box-Omr...087?nav=SEARCH

There is almost no difference in the package as long as you ignore the shaft end style encoders like US Digital commonly provides for use in FIRST style gearboxes. Personally my success with that style encoder in FIRST and my MaxNC CNC machines is limited anyway.

So really all you need to add is the board to decode, and if you do not want to craft that:
http://www.superdroidrobots.com/shop...r-buffer/1523/

http://www.usdigital.com/products/in...cs/LFLS7366R-S

So if you can make this work with a 1/4" shaft potentiometer you can make this work with an encoder. Sure you need some extra electronic parts and cost, but the encoder provides clear signals.

Also the potentiometer is cheaper but wear can become an issue more quickly and then you have analog issues.