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Description: These are very thin variable potentiometers. By pressing down on various parts of the strip, the resistance linearly changes from 100Ohms to 10,000Ohms allowing the user to very accurately calculate the relative position on the strip. Can be used as an accurate positional indicator for CNC head positioning, variable user input (volume level input for example), straight user input (multiple button areas translate to given resistance levels), and many other applications.

Unit comes with adhesive backing. Connector is 0.1" spaced and bread board friendly.

Note: These potentiometers work great with a finger, or stylus. For premium repeatability, the wiper listed below is perfect for machine and object positioning.

Documents:

Comments 17 comments

  • I got one of these in an Arduino inventors kit. One of the projects uses it (as a voltage divider, reading the output from the middle pin) to control the color of an RGB LED. The sensor was not acting at all the way I thought it would when I was not touching it. I realized that when nothing is touching the sensor, the voltage is at about 33% of the voltage range. Touch the sensor near the connections, and the voltage drops to nearly 0 or ground. Touch it near the top (away from the connections) and the output voltage rises to whatever the high pin is. This makes it impossible to tell when the sensor is being touched and when it is not. I put a resister (10K) between the ground pin and the output pin, and now the output is exactly what I want. I can look for a voltage of 0 to see that it is not being touched, any value above zero means it is being pressed. The higher the voltage, the higher on the strip it is being pressed.

    • Tony’s “..put a resister (10K) between the ground pin and the output pin, and…any value above zero means it is being pressed. The higher the voltage, the higher on the strip it is being pressed.” should be added to the description.

    • I didn’t find the way to get 0 value when the sensor is not pressed until I read your post, which is the therorical reason of putting the resistor?

      A suggestion for sparkfun team: This tip should be in the guide of the inventor’s kit, for the beginners is essential

      • The simplest way to think about it is you are “pulling” the output to ground, or 0 volts, so that will be the default reading. You use a large resister so that the effect is not very strong and can easily be overridden by the rest of the circuit. Also, using a large resister limits the amount of current being drawn / power being wasted.

    • Thanks Tony, that resister totally solved the problems I was having with my SoftPot, and as it happens, also a Sharp IR range finder!

  • This softpot came in the SparkFun Inventor’s Kit. The pins do not fit into the breadboard as shown in the kit guide. I didn’t want to ruin my new softpot by modifying the pins (and I’m too much of a newbie to solder yet). So, I solved the problem by gently pulling the black heat shrink plastic off one end of three jumper wires. (I only ruined one wire, before successfully having 3 wires with a black end removed and the pin exposed). I then attached the 3 plastic bits to the three prongs on the softpot. Lastly, I gently inserted the now exposed pins of my jumper wires into the 3 plastic bits until the ends just ever so slightly appeared at the base of the softpot. This created a fairly stable connection between the three jumper wires and the softpot and I was able to complete the circuit successfully.

  • Why we need to put resistor between Ground and output pin. Sorry my question may be very silly but I am new to electronics…

  • i Love Analog Sensors ;)

  • Hi gyus, I’d like to use this in my project where I’d like to measure distance traveled by a moving stage. The thing is the stage only moves from about 2-5mm, you think this sensor can resolve changes this small? The sensor would be mounted on a flat hard (aluminum) surface and the stage would be “touching” the sensor using the supplied “stylus” so the force applied will be quite constant. Thanks for your tips!

  • .

  • Hi can you bend softpot membrane potentiometer along with your finger? If it can be bend then will the resistor value changes accordingly?

  • I made the following Python script you can run on the Beaglebone to reduce the crazy noise and output a better value range to work with, Script URL: http://pastebin.com/hfekCBuW

    I found out using this script that when nothing is being pressed on the soft pot anymore it resets to the highest value. Hope you guys like this!

  • This component is very sensible and fragile but under right circomstances it is extremely precise. If you want an accurate reading, you have to stick it to a hard surface. When you’re not touching it, it returns a lot of random values (noise), making it pretty unreliable for creating a “touch” human interface.

    • if they can be extremely precise, that sounds better for my purpose than using flex sensors. what about if you were wearing it on a glove and used the parameters to control effects? when you say random values whilst not touching it, how much noise/signal are you talking about please?

  • I noticed that too. Looks like it should work as long as you leave a little of the transparent part intact.

  • Seems a bit wide for what i’d like to use it for… Can it be trimmed a little bit and still operate correctly?


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