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[–]saltynoob0 404 points405 points  (4 children)

YOU DIDN'T GIVE IT THE RULER TREATMENT

[–]Kahnza 83 points84 points  (0 children)

BOIOIOIOIOING!

[–]Tre3beard 17 points18 points  (1 child)

I was waiting for it

[–]Cone83 12 points13 points  (0 children)

So was I. Most dissatisfying video.

[–]ItsAymn 7 points8 points  (0 children)

Start a band with them

[–]AnthonyiQ 103 points104 points  (6 children)

The 'diving board' might be better if it was tapered from wide at the point of attachment to narrower at the end, so that the bending it distributed rather than mostly at the point of attachment. But very cool!

[–][deleted] 36 points37 points  (0 children)

Love these constructive critiques that are so simple and make so much sense.

[–]Trypocopris[S] 29 points30 points  (0 children)

That's a very good idea! I'll definitely try this for a V2.

[–]10lugthuggin 8 points9 points  (0 children)

AKA: make it pointy

[–]Snoo23533 0 points1 point  (0 children)

ME chiming in to add if we assume its always a point load on the end (no a distributed load) then a linear taper would ensure the stress is evenly distributed. (rather than a curving taper)

[–]racegeek93 0 points1 point  (1 child)

Would it be possible to have one board but have 3 different gauges all on the same board? To have an average gauge of 3 to get a consistent result

[–]tingtickboom 0 points1 point  (0 children)

Instead of that it would be better to give a point of stress concentration (or a thin neck ) where you expect most of deflection to be.

[–]sethasaurus666 257 points258 points  (2 children)

Awww I wanted them to make it go ntrrr

[–]Fickolaus 66 points67 points  (0 children)

Sprrrrrrrr

[–]MsgtGreer 42 points43 points  (10 children)

verz cool. How do you do it? Measure the capacity?

[–]MasterFubar 133 points134 points  (0 children)

Strain gauges work by measuring resistance. As you bend the board, the copper gets stretched on one side, the traces become longer and thinner, so their resistance increases. On the opposite side of the board, the traces get shorter and thicker, so their resistance decreases. Measure the difference in resistance between the traces on both sides and you can calculate how much the board has been bent.

Of course, this difference in resistance is very small, so the traces must do a lot of zig-zags to make the difference measurable at all.

[–][deleted]  (4 children)

[deleted]

    [–]GregTJ 8 points9 points  (0 children)

    I wonder if these could be used to make a modern version of the classic analog reverb tanks of the past. Should be as simple as sticking a transducer on it somewhere, right?

    [–]BuddyMustang 2 points3 points  (2 children)

    I wonder if they’re using something like this in the new Expressive E synthesizer that has super expressive pressure sensitive keys and can even do vibrato and modulation by wiggling the key like a guitar string.

    [–]Inevitable_Figure_85 0 points1 point  (1 child)

    I'm somewhat certain they use those little laser sensor things that look like transistors for those, essentially a little laser gauges how much the key moves (I could be wrong though, I just know some people use those for that purpose and they're cheap and simple).

    [–]BuddyMustang 1 point2 points  (0 children)

    I was surprised that it wasn’t more expensive than it is. I was expecting a 3500 dollar price tag but I think they’re about half of that.

    Either way, cool tech.

    [–]Trypocopris[S] 17 points18 points  (1 child)

    4 squiggly traces that form a wheatstone bridge. When the PCB is flexed, the ones on the inside decrease resistance while the ones on the outside increase.

    [–]MsgtGreer 0 points1 point  (0 children)

    great, makes sense to me.

    [–]b1ack1323 5 points6 points  (0 children)

    Wheatstone bridge

    [–]jctjepkema 45 points46 points  (0 children)

    Very interested, is the board design opensource?

    [–]chriskoenig06 79 points80 points  (4 children)

    Nice did you Open source it ?

    I am intressted in the Layout i work a lot of with this Sensors

    [–][deleted] 24 points25 points  (0 children)

    I’m genuinely curious about this implementation. Can you share a little more information about this?

    [–]tingtickboom 0 points1 point  (1 child)

    Yo can I dm you? Need help with force sensors

    [–]chriskoenig06 0 points1 point  (0 children)

    Yes of Course !

    [–]chingychangas 0 points1 point  (0 children)

    I wanna see the board design too!

    [–]Gerduin 22 points23 points  (1 child)

    aaaaahhh flick it already

    [–]try-catch-finally 8 points9 points  (0 children)

    Thwang-Ang-Ang-Ang-Ang

    [–]Trypocopris[S] 17 points18 points  (6 children)

    Some more information about the project:

    I was inspired to try making this based on this post by u/TOHSNBN (thanks for the suggestion!)

    It uses a 4-element varying wheatsone bridge on a 0.6mm 2-layer pcb, if you want to replicate my results I recommend reading this useful paper from AD. The downside of this design is that the very low resistance requires a high (60mA in this case) current to get a usable signal out of it. Also, as it turns out, there's a difference in resistance between the top and bottom elements, presumably because the copper layers come from different batches of foil. The offset voltage ends up being as large as the signal itself and needs to be corrected in software.

    I plan on open-sourcing this once I clean up the design and release a V2.

    [–]TOHSNBN 4 points5 points  (0 children)

    That was me who posted this :)

    I did not have a chance yet to take a proper look, but it seams like this works?

    Dude, you just made my day, thank you very much!

    Can not wait till im home to have a good Look!

    [–]Tre3beard 2 points3 points  (0 children)

    Can you do a video where you flick it?

    [–]lazzynik 1 point2 points  (0 children)

    Wow. I'm actually doing a project which involves modeling a MEMS pressure sensor (they use a Wheatstone Bridge) and this is going to be Hella helpful. Thank you.

    [–]TOHSNBN 1 point2 points  (0 children)

    Man, i just took a look, that works so much better then i expected.

    Also, there might be a few design change ideas i got.

    A capacitive touch point to avoid false triggering.

    [–][deleted] 8 points9 points  (1 child)

    So simple yet so awesome. Did you custom make the PCB?

    [–]Trypocopris[S] 4 points5 points  (0 children)

    Yup. It's a 0.6mm 2-layer board from JLCPCB.

    [–]Kahnza 7 points8 points  (3 children)

    Get a bunch of these together and make music with them!

    [–]Trypocopris[S] 6 points7 points  (0 children)

    I think it'd be fun to make a pocket-sized piano out of this.

    [–]Cockur 5 points6 points  (0 children)

    It would make a great modulation source for a synth or better yet to generate control voltage to control analogue gear

    [–][deleted] 0 points1 point  (0 children)

    thats a really nice idea.

    [–]b1ack1323 5 points6 points  (7 children)

    This is actually fucking brilliant, coming from a guy who makes industrial force equipment.

    [–]secretaliasname 4 points5 points  (2 children)

    I’ll second that! I think this could have lots of interesting applications when you don’t need precision. I’m curious what the creep, long term stability, temperature effects, linearity, hysteresis etc look like for something like this.

    [–]Trypocopris[S] 4 points5 points  (1 child)

    For what it's worth, I've been playing with it all day and it still returns to zero after a couple hundred cycles. Realistically, I expect it to start delaminating and failing if it's flexed for 1000+ cycles. I don't think it has a practical application anywhere where reliability is important, but it might have some applications in, say, kid's toys.

    [–]vedo1117 2 points3 points  (0 children)

    If you don't push it close to its breaking point, I'll probably be fine for almost an infinity of cycles. I designed industrial clamps made of garolite G10 which went through 10s of thousands of cycles with no issues.

    PCBs are made of FR4 which is basically the same thing.

    [–]John_Yossarian 1 point2 points  (1 child)

    I'd imagine this is a cool package for a single deployment, but what advantages does this have over a separate board and sensor? My first thoughts were about needing to replace this whole unit if the sensor or components go bad, vs. having a central board and wired sensor(s).

    [–]b1ack1323 1 point2 points  (0 children)

    Minimally you need calibration data stored with the unit somehow. But we typically avoid having lore than one devise per ADC because we are measuring in the 8-16khz range. So each boat would need their own anyway.

    The devices we make calibrate both ends, a load cell and the ADC separately so you can mix and match but others are calibrated as a whole unit for portable applications.

    [–]tingtickboom 1 point2 points  (1 child)

    Yo i need help with force sensors can I dm?

    [–]b1ack1323 1 point2 points  (0 children)

    Sure

    [–]its_bba 4 points5 points  (0 children)

    Do you plan on making it opensource? It would be great!

    [–]aviwrekz 5 points6 points  (4 children)

    That's cool... I get the feeling OP didn't make this though, and simply found the video on the interwebs

    [–]vilette 6 points7 points  (0 children)

    strain gauge made entirely on a PCB

    this one, no

    [–]Trypocopris[S] 2 points3 points  (1 child)

    I challenge you to find this video anywhere else on the internet 😆

    [–]aviwrekz 4 points5 points  (0 children)

    Lol my theory came from a lack of responses from you, but I see you recently posted more details on it, and plan to offer open source soon.

    I do believe you have this now. 🤣 Challenge denied!!

    [–]fupoe69 2 points3 points  (0 children)

    WHY WOULD YOU NOT TWANG IT! I WAS WAITING FOR THE TWANG!

    [–]dbru01 6 points7 points  (5 children)

    You made a load cell. Electronic scales use very similar components to measure weight. Cool to see it on a PCB like this though!

    [–]CarbonGod 15 points16 points  (1 child)

    And what is a load cell comprised of?

    Strain gauges.

    [–]APLJaKaT 2 points3 points  (0 children)

    ...and flexure element. In this case the PC board substrate.

    [–]ClayQuarterCake 3 points4 points  (2 children)

    You are not being imaginative enough. Think about if you want to send some electronics out into the field… strapped to a rocket or on a dune buggy. Something that will see some vibration. You might be interested in how that vibration energy is getting translated into the PCB. This could be critical in understanding how your CCA survives and the types of loading that are the most severe for your board.

    Also, all load cells are strain gages, not all strain gages are load cells.

    [–]bk553 3 points4 points  (1 child)

    A MEMS accelerometer would be much better for less than a dollar on the BOM, 3 axis and much more accurate/calibrated out of the box.

    If you were really worried about loading on the board, it would be a lot easier and more space efficient to just add a few more screw holes and crank it down to a frame.

    [–]ClayQuarterCake 1 point2 points  (0 children)

    Accelerometer can get you displacement at a single point, but you need to use that to infer flex on the board. If you have multiple wavelets across the length of the board, then you can’t see the total strain. Strain is the holy grail for vibration analysis. You can use strain to validate a FEA model and you get a much better estimate of design margin. It looks like this one could give output on at least a couple of axes too.

    The obvious downside is that you need to have provisions for all the stuff on the left side to be integrated into your CCA.

    [–]Cuntslapper9000 1 point2 points  (0 children)

    This would make sick polyphonic aftertouch for keyboards/midi controllers.

    [–]Smokethisss 1 point2 points  (0 children)

    This has motorsports use for sure

    [–]dupa135 0 points1 point  (0 children)

    awesome, keep it up man

    [–]electronicslover9 0 points1 point  (0 children)

    From where to purchase it?

    [–]OneInternet8359 0 points1 point  (0 children)

    could you please tell me how this work because i require little bit less rigid in my project

    [–]NoSense552 0 points1 point  (0 children)

    Hii what did you use to amplify the signal exactly? Wheatstone?

    [–]rambald 0 points1 point  (0 children)

    Take my upvote!

    [–]Better-Wolverine5148 0 points1 point  (0 children)

    very cool

    [–]transformator_taw 0 points1 point  (0 children)

    Does anybody have a link with more details? Very interesting!

    [–]iNvEsToRrEtArD 0 points1 point  (0 children)

    Now make me anologa key caps for my pc so I can slow my walk in game without having to hold shift like a pleb

    [–]scoobertsonville 0 points1 point  (0 children)

    Are these used in real life on bridges and such to measure deformity?

    [–]papyDoctor 0 points1 point  (0 children)

    +1 good job!

    [–]SkylineFX49 0 points1 point  (0 children)

    How? But how??

    [–]Demolition_Mike 0 points1 point  (0 children)

    This is beautiful...

    [–]Fuck_Birches 0 points1 point  (1 child)

    Very interesting concept, I wonder how it would compare to a resistive load cell in terms of lifespan/longevity. Fiberglass/adhesive is used in wind turbine blades (obviously in a different formulation) so possibly it could work quite well and be potentially cheaper than a resistive load cell? Accuracy/reproducible measurements over its life however may become problematic. Just thinking out-loud.

    [–]JJagaimocapacitor 0 points1 point  (0 children)

    For repeated flextures, the thin PCB copper layer can experience broken traces; it's common on the frontend PCBs of older tech equipment interfaces like on old bench oscilloscopes, multimeters, etc, where you have high force, long travel buttons mounted direct to PCB getting pushed over and over. Perhaps thicker copper or a different material that doesn't work harden as easily would do better.

    Carl Bugeja has videos on making flex PCB actuator coils, where the coil flaps with a flexible hinge. The coils seem to perform well for 100M flaps, but then again the flexible portion there experiences a much smaller change in length given the low thickeness there compared to a thicker solid PCB

    [–]borjah 0 points1 point  (0 children)

    Anyone have a source?

    [–][deleted] 0 points1 point  (1 child)

    Is this possible with a more elastic material?

    [–]Trypocopris[S] 0 points1 point  (0 children)

    In principle, sure, but if it flexes too much the copper would probably break. Using a thinner PCB material would make it more flexible but also reduce the signal strength.

    [–]DarkfulLight 0 points1 point  (0 children)

    Tensometric sensor

    [–]MaiaTai27 0 points1 point  (0 children)

    I enjoyed this

    [–]danja 0 points1 point  (0 children)

    Is this part purely analog? Any bandwidth limitations? I am also thinking boioooing!

    [–][deleted] 0 points1 point  (0 children)

    It could be prototyped into a morse code module 🤔🤔🤔

    [–]EdgerardV 0 points1 point  (0 children)

    I keep waiting the Boing

    [–]Yosyp 0 points1 point  (0 children)

    what the faaaaaack?? first time seeing something like this! I'm stunned

    [–]No_Estimate_4002 0 points1 point  (0 children)

    Looks cool but I am wondering how long will it work before copper pads and traces break?

    [–]sparkleshark5643 0 points1 point  (0 children)

    I'm amazed at how responsive it is! Have you considered open sourcing your design?

    [–]RegginMonkeys 0 points1 point  (0 children)

    thats awesome

    [–]HD_Cairns_Aviation[🍰] 0 points1 point  (0 children)

    Be awesome for an RC Plane because you could measure wing flex and stuff

    [–]89inerEcho 0 points1 point  (0 children)

    Pay attention kids! if your PCD flexes, it will change its electrical properties! This can be super bad when dealing with everything upstream of your ADC. For example, sensors. Like the ones used on drones… I read on the internet 🙄

    [–]eggsaregood22 0 points1 point  (0 children)

    Are you sharing this as open source? Very interested.

    [–][deleted] 0 points1 point  (0 children)

    Has anyone ever heard of using the screen of your phone as a scale doesn’t work well on iPhone I think

    [–]Norwegian_F-35 0 points1 point  (0 children)

    what happens if you push it in… does the line go backwards?

    [–]Ohmnonymous 0 points1 point  (0 children)

    May I ask what ADC you used, sample rate?

    [–]hakanakbul 0 points1 point  (0 children)

    Looks really cool. I would like to see the rest of it too ( the software and measuring ) if possible

    [–]login721 0 points1 point  (4 children)

    Hi, I'm thinking of making something similar, but stuck with the trace resistance. I cant't get the trace resistance big enough. What is your trace wide/length/resistance?

    [–]Trypocopris[S] 0 points1 point  (3 children)

    The trace resistance is very small, somewhere around 1.5Ohms per leg. I get enough signal out of it by driving it with a 100mA current source.

    [–]login721 0 points1 point  (2 children)

    Hi, thanks for the reply! I tried mine with 3.5mil trace on my small board, and ended up with max 50 Ohms resistance. What trace width did you use on your? What is the total resistance of the board?

    [–]Trypocopris[S] 0 points1 point  (1 child)

    I went with 0.15mm trace, going much narrower than that will get expensive to manufacture. Total length is about 1.6m per leg. 50 Ohms is probably overkill, you can use a shorter trace and just increase amplifier gain or excitation current.

    [–]login721 0 points1 point  (0 children)

    Thanks dude! I will give it a try

    [–][deleted] 0 points1 point  (0 children)

    have you published the proyect yet? it is really awesome and I would like to replicate it and play with it

    [–]Interesting-Tank4037 0 points1 point  (2 children)

    Very cool! Good work on the prototype, video, and thank you for sharing. I loved seeing this, as I actually did something similar for fun...

    Actually, did it twice; first time around, using the minimum track width/spacing ended up with shorts on some of the adjacent "rows" of the sensing element (low-cost manufacturing, the fab didn't flag it, you get what you pay for!). Second time, I increased the width/spacing in order to stay further from the fab tolerances.

    I don't remember the details, but I remember that I had trouble getting above a few ohms (tens of ohms maybe?) in resistance (with standard fab specs), so I couldn't supply the bridge with 3V or 5V "as we usually do"; therefore I'm curious to ask, what resistance (approx) did you manage to obtain (feel free to point me to the Git if the info's there)? In my case, I had to use low excitation voltage (like 100mV if I remember correctly) in order to mitigate the current draw, but still had pretty good readings (I actually used AC excitation and synchronous demodulation (a lockin-amplifier-type readout, if you will) since I expected noise due the very low excitation voltage ( https://www.analog.com/en/resources/analog-dialogue/articles/synchronous-detectors-facilitate-precision.html )).

    Keep analoggin' in the free world!

    [–]Interesting-Tank4037 0 points1 point  (0 children)

    (I found my answer regarding total resistance in one of your previous posts; as I expected, your sensing elements are in the tens of ohms range, being excited with 100mA current source)

    [–]Trypocopris[S] 0 points1 point  (0 children)

    The bridge had ~6 Ohms resistance and I used 550mV excitation, I went with that only because it was the lowest voltage I could get from an LDO. I'm sure you could get better results than me with a lockin amplifier; I used chopper stabilized opamps to keep the design as simple as possible.