## Variations

• Use it to Dim an LED (video + code)
• Use it to Make some noise (video)
• Try different kinds of foam (test resistance across the foam first to make sure it's conductive)
• Cut unusual shapes
• Test different foam configurations (e.g.: multi-layered foam)
• Test different plate materials (e.g.: aluminum foil on cardboard/plastic/wood)
• Make humongous FSR arrays

SensorWiki FSR page explains FSR theory and use, with examples
Protolab explanation of FSR use in the context of other sensors

Thanks to Dane Kouttron and Zach Barth for introducing this technique to me, and leaving a few FSRs around the eclub.
<p>nice, simple and easy. thanks for sharing!</p>
<p>Hello, thank you for the tutorial, I want to know if there are any way to connect to arduino in order to get the variables changing when applying force, I need to do a surface that will be able to detect when people hands over it and then create a reaction in a liquid (non newtonian) using speakers / changing frequencies depending force applied.</p><p>can it be possible?</p><p>thanks!</p>
<p>I am new to FSR but I think it is no different than connecting a potentiometer to arduino. If I am correct, analog read is just reading the voltage in range of 0-1023. So if you connect FSR red side to 5v, connect a resister in series with FSR and connect the resister to any analog in then it should give a read for you. of course you need to program arduino but you can figure it out yourself</p>
<p>hey thank you for your reply, yes Ive purchased some FSR to use in the surface, used some sample codes on internet to get some numbers from it depending force applied, the thing is how can I use this numbers to control the volume in a external power amplifier who is connected to a speaker, so depending people force over sensor the volume increase reproduced by speaker. regards!</p>
<p>I'm looking to be able to apply potentially hundreds of pounds to a force sensor and detect the weight applied. Would this work for this project?</p>
<p>I wouldn't count on it. Your better off just getting a few load sensors from alibaba or ebay for a few bucks. These aren't very accurite.</p>
<p>if you wanted to measure force in the hundreds of pounds could this work? </p>
I could use some of those... Are these similar to what you would find in a keyboard? Obviously keyboards work generally via two contacts and a spacer sheet. Do you think I could use a keyboard circuit to make some of these?
As far as I know, most keyboards keys are switches. According to <a rel="nofollow" href="http://computer.howstuffworks.com/keyboard3.htm">HowStuffWorks</a> there used to be &quot;foam element&quot; keyboards, but I don't know if they were more like switches or thresholded FSRs.<br/><br/>I'm guessing a keyboard circuit wouldn't be very useful for making a matrix of these; but I haven't really dissected enough keyboards, so don't let me dissuade you :)<br/>
A keyboard made like this would be terrible because it would need more circuitry (expense) to register key presses, have a far lower number of cycles before wearing out, and force slower typing since foam doesn't expand as fast as a spring or bubble membrane does, keytravel would be slow in both up and down directions and not tactile.
The wear factor is a bother wirh fpoams i've seen. How tp make my own...the next bit
you ac-dc, are a very sad person - and properly ignore the 'be nice' comment policy.
oh the irony
I noticed you don't have any instructables posted, ac-dc. It seems like you're knowledgeable about lots of different topics, though -- I'd love to see what sort of projects you enjoy working on.
My interests are more in the unimaginative, pure sciences. I'm not really the inventor type personality, more of a system analyst type, plus taking this particular Instructable as an example I don't need a force sensitive resistor for anything even if other people might. I tend to buy professionally engineered products, it is very rare to have a real need for a product that doesn't exist or at least come close to the goal but can be modifed. When I modify things it seems easy enough to just write a paragraph instead of an elaborately presented instructable. For a simplified example, when I made a charging base for an MP3 player, I just stuck stainless screws on the player case wired to the battery contacts inside, screws to match up to the contacts in an old phone recharger cradle and put a LM317 current limiting circuit in the cradle. Pictures and a description of drilling holes, soldering wires, or telling someone to look at LM317 datasheet for a schematic all seem like obvious details to me. A lot of the instructables seem that way to me, like the ideas are good, the end results can sometimes be desirable, but most of the info is obvious enough it wouldn't need to be written or pictorialized. I do find one thing about the Instructables site disturbing though, that no matter what a project is, is seems as though people want to censor fair analysis of the cons and only focus on the pros of something. I feel it is best to fully weigh the cons too, otherwise there's no good way to compare to other alternatives. This is only a generalized comment, has nothing to do with Force Sensitive Resistors.
AC-DC: Try this ... Look at each of your &quot;junked&quot; projects and try to remember what you learned from it. Travel along this thinking to discover how it is that you now know what you know about why that project &quot;didn't work out&quot;. Try some meds. But whatever you do to fix you own thinking, PLEASE DON'T DESTROY THE INCENTIVE FOR YOUNG MINDS (of any age) TO RECOGNIZE THAT FAILURE IS A REQUIREMENT FOR LEARNING!
lol, ac-dc's comment is perfectly logical and realistic, not mean
being nice doesn't mean you have to be a kissass. he was just stating the fact that this wouldn't work.
I agree with you comment. But for the cause of good information I would have to say, perhaps he should read the question first before commenting.
By "Both are not inexpensive to produce" I meant metal contact and foam element", not the 3rd type I mentioned which was silicone dome element which are inexpensive, and come to think of it they're also used on lots of other products like car key remote controllers.
I didn't ask if you could make a keyboard from these. I was asking, could I hack one apart to obtain the individual pressure switchs from a key board.
I think it's fairly obvious this wouldn't be the best sensor for typing -- for all the reasons you mention. I think he meant "could I interface to a bunch of these by reusing circuitry from a keyboard?"
You are correct.... Certain types of keyboards have circuitry which allows you to obtain hundreds of these easily.
how to make force sensor with 3 pins?????
Dou le layer sandwich?
Pretty cool post!<br> Instead of using copper pcb can a rfid label be used instead? I'm thinking something like two of the attached image:<br>
Not sure why it uploaded so many images..
very good tutorial about how to build and interface a force sensor. Also, I add this tutorial in my article about <a href="http://www.intorobotics.com/force-sensors-reviewed-and-programming-tutorials/" rel="nofollow">force sensors</a>
Can not be measured accurately
i am thinking of building a weighing scale out of this. but how much foam and what is the best dimension that you would think i have to make for it to be able to hold and correctly be able to measure a 1kg weight?
Would you please describe why we need the conductive foam? it is very new for me. The distance change cause capacitance change. but I don't really know about the conductive foam.
the conductive foam changes resistance as it is compressed. i imagine that it's a network of resistors, and more of them are touching each other when you compress it. this means the average resistance from one side to the other is decreased because the path is more direct.
What kind of glue do you use? I tried gorilla epoxy, but it does not hold so well...
i use hot glue. for pretty much any electronics, i always use hot glue :)
For those of you who have actually built this, what did you use to protect the copper? Conformal coating spray is pretty expensive, and I plan on trying to make rather long FSRs so coating with solder might be a bit difficult as well. Suggestions?
Liquid plastic coating. Like plasti mix.
what's liquid thin?
:( My first thought was "Awesome, now the jedi can't touch it". Damnit.
Or maybe, only Jedi can use it...<br />
A few years ago I used a fine grade Pressure Sensitive Material to make an 18 channel control board for lights. I had Vellman dimmers that ran on a 0-10 V control voltage, and I made 18 pads similar to these to make voltage dividers to control them. The guy who gave me the PSM as an industrial sample died though, and I have no supply for more as needed. I am really glad to find the suggestions in this project!
I'm glad to help/provide a place for links to congregate.<br/><br/>Be sure to check out Hannah's work too: <a href="https://www.instructables.com/member/Plusea/">https://www.instructables.com/member/Plusea/</a> She does a ton with resistive material, and has some links to suppliers.<br/>
Would you be able to use a potentiometer instead of the fsr's? I can't think of a reason why not-i just wanted to check.I'm definately going to do this because i'm making an electronics order tonight but i can't get the foam in a small lot and don't want to spend £13 (\$26) on foam that i know i will only use once.
Yes, you can use potentiometers in place of FSRs. You'll just want to use one of the outside pins and the center pin. Both FSRs and potentiometers are variable resistors. The advantage of a potentiometer is that you can put "low" (ground) on one side and "high" (say, 5 V) on the other side, then "tap" to get a value in between. The advantage of FSRs is that they are sensors -- you don't have to "interact" with them using a screwdriver :) Of course, if you have big pots with knobs/dials, that's not necessarily an issue. Keep in mind, if you're using these for the Nandhopper, potentiometers are generally 1k-10k ohm max, so you'll need to use bigger capacitors to make up for this.
I have 100k pots.
See the explanation of cap selection in the post below. You're looking for something like <a rel="nofollow" href="http://www.google.com/search?q=1+%2F+(500+hz+*+100+kiloohm)+in+nanofarads">20 nanofarads</a> for the caps.<br/>
If i used 1K LIN.POT what capacitor would i have to use?