Flex Sensors Repaired

It looks like the repair worked. Hopefully this will last as I plan on using the flex sensors for a bunch of things. The circuitwriter polymer does glob over the contact and reasonably should tie everything together. Hopefully it will stick to everything.

I got a comment from tigoe who wire wraps rather than solder, I will try that next time. I can imagine that the plastic of the flex sensor softened and may have compromised the crimp. tigoe also suggests providing some stress relief to the end by the connector. That area gets thinner is want to bend more. Also my wiring is solid Cu and doesn't want to bend and puts more stress on the end of the flex sensor. I was thinking I might try sandwiching the connector area and wiring to support the flex sensor, maybe between 2 pieces of mylar the width of the sensor strip and .25" over the wiring and .25" onto the more stiff part of the flex sensor. I don't want to have a fix interfere with any final application though.

tigoe also helpfully points out that the code is online at http://www.makingthingstalk.com. I will probably take advantage of that but for now I am typing in the code from the book so I can understand it better. I am pretty new to the arduino programming and processing language and format. It is amazing how fast you can make a project go with cut and pasted code.

One thing I hoped would be "fixed" also was that difference in the flex sensors readings would disappear, it appears that they are just like this. It is not a big deal I suppose, since I can compensate in the programming, but it limits the interchangeability of sensors. I imagine that I could make a calibration subroutine to take care of that but it would be nice if I could just swap and have them be identical in application. I might be that it works out that they have to be calibrated no matter what.

The readings on the first sensor are 8.9 KOhms relaxed - 8.1 KOhm flexed toward the white square side, and ~35 kOhm toward the black side (flexed to a U shape).
the second sensor are 12.7 KOhms relaxed - 11.0 KOhm flexed toward the white square side, and ~44 kOhm toward the black side (flexed to a U shape).

Obviously the sensor is best in one direction!


Before


Apply Circuitwriter


After