Force-sensing resistors: Any experience?

[Mark Hammer]

I was in the local Active/Future electronics store today and saw they carried two kinds of force-sensing resistors.
https://learn.adafruit.com/force-sensitive-resistor-fsr

I'm curious about these as alternate controllers; particularly since they don't take up all that much room.  Strikes me that they could be used for situations where something could be controlled by a voltage divider that isn't especially fussy, or by a variable resistor.  From what I understand they don't necessarily respond quickly.  But there are plenty of things where you don't necessarily want to make something change instantly.

Anybody ever tinker with these?

[karbomusic]

I have various sensors such as flex and impact and some other stuff. I also have an ultrasonic distance sensor. Using as a voltage divider is their primary usage just like using one with an LDR. Old news to you I'm sure. I don't suspect they'll respond as quickly as one might need as an LFO et al but my use (idea wise) wouldn't need that speed anyway. Maybe I'll throw a quick fuzz on the breadboard and use one of the sensors to change gain or tone just to see.

I've used some quite a bit with my Arduino but haven't gotten around to sticking one in an audio circuit yet but I can usually treat them like an LDR overall, same thing it's just reacting to something other than light.

[Mark Hammer]

For an application like varying LFO rate or altering feedback, I don't think it wouldn't be prohibitively slow.  The bgger question is how to apply the force.  I'm thinking that switch actuators like the ones Small Bear carries might be usable.  http://smallbear-electronics.mybigcommerce.com/switch-actuator-for-b-o-b/

That'd be kinda cool to have a 1590BB with a bypass in one corner and another plunger for controlling sweep rate for a modulation effect, whether chorus, flanger, tremolo, or phaser.

[mac]

I used a Tekscan Flexiforce to control a Colorsound Inductorless Wah Wah.
I prefer the feel of a pot. BUt I didn't give it much time on the breadboard.

mac

[karbomusic]

That'd be kinda cool to have a 1590BB with a bypass in one corner and another plunger for controlling sweep rate for a modulation effect, whether chorus, flanger, tremolo, or phaser.

I've been considering as part of the pedal surface like a 1 mm thick rubber square like the drum pad on a keyboard. Actually, I'd more prefer it just be part of the floor in front of the pedal board.

[smallbearelec]

I do carry these:

http://smallbear-electronics.mybigcommerce.com/new-category-4/

have not yet made time to experiment. Suggestion: Remember the old "electronic bongo" circuit? I wonder what would happen if you stuck one of these sensors in the right place in that just-below-oscillation-point Twin-T circuit...

[Mark Hammer]

I do remember "Cabonga", et al.; all those old James Barbarello circuits.

But I also remember this rare bird from the folks who brought us the Chapman Stick:  http://www.effectsdatabase.com/model/stick/patchofshades

I didn't pore over it in great detail, but the patent document that the effectsdatabase links to suggests that a pair can be used as a voltage divider.

Hmmmm....

Chapman's seem to be custom sized-shaped, to accommodate the overall pad size in the pedal.  I'm wondering how a pair of the a-little-too-big square ones, or small-enough-but-not-square-ones could be adapted to make a foot-controlled pot.  On the other hand, scratch the idea of using the plunger-style actuator.  Just adhere the thing to the surface of the pedal, adhere a piece of cork or piece of "fun foam" over it to protect and absorb shock, and one could just push down with one's foot.  Judicious placement of series and/or parallel resistances toarrive at the final resistance-range you need for the parameter, and you're in business.  I suppose the tricky part will be where to place it.

[karbomusic]

Just adhere the thing to the surface of the pedal, adhere a piece of cork or piece of "fun foam" over it to protect and absorb shock, and one could just push down with one's foot.

Exactly. Back in the '90s I was on the road and the momentary switch for my now ancient QuadraVerb GT went missing between town A and town B. The show started in an hour and there was no time to find a useable replacement. A match pack, duct tape, two quarters and a guitar chord with one end cut of later, I created a momentary switch which I duct taped to the floor. It worked so well I used it for the next few months because having it on the floor with a 1mm profile, and not up on a pedal board was so nice comparatively which brings me too...

I haven't went too far with distance/flex/pressure sensors yet because they typically have a similar requirement, a foot, balance etc which has such low resolution/accuracy of control. It's the same thing I fight with on my volume pedal. Getting to it quickly and adjusting accurately with high resolution and control during the heat of battle since I'm essentially having to keep balance with the other foot. I need to solve that in some way since I don't have a spare arm/hand. What I really would like is to simply control it with my brain. Yes that exists....

OK, a little Star Trekish but entirely possible albeit very expensive; been following Emotive for a couple years now. If I could control my volume or other params with my brain, I'd be set!