Tutorial: Op-amp circuit for force sensor signal conditioning

This is a description of a simple opamp circuit that will translate the variable resistance of a Flexi-Force sensor into an analog voltage and maintain linearity across the sensor's measurement range.

Your feedback and topic suggestions for future tutorials are welcome.

[Infinitesap]

Thanks very much. I think that your approach with a regular problem (measuring), designing the curcuit, doing the math, and the showing it working is SO EXTREMLY AWSOME.
This is exactly what I need. I can see a lot of YT videos regarding theory, but from my point of view its difficult to get from knowing behavior of components to a real application.
Please make more videos like this. And from my perspective you may add quite more theory. I think the term "Applied Science" really is the fundamental challenge in this world, and apparently you are one of the very good sources. Thanks a lot :-)
I would be so thankful for a in depth video on H-Bridges, the basics but also with more power consumption by the motors (for diy robots e.g.) Thanks in advance.

[pepe]

man another ripper video. we need to make a statue of you in the townsquare looking to the future holding an opamp

[ohm]

I love watching your videos because your projects are always different and you're so good at explaining things! You should come teach at Purdue!!!

[DJTrancenergy]

Great video! Probably one of the few in YouTube that explains designing a circuit quite well
The only thing I didn't catch was your noise considerations. The piezo can have large impedances, and the op-amp current noise will generate a voltage noise source with it. Perhaps for your purposes it doesn't matter, but in real life design, one is sure to provide a detection limit based on it as well.

[davidsnaith]

Thank you so much! You taught this old mech eng exactly what I needed to know to get my FSRs working!

[neptunetm]

Great stuff, as usual. I really enjoy your channel - straightforward, to the point, no BS!

[electroniceeltube]

Nice videos you have!

You could reduce the different number of voltage regulators of your design if you use the internal voltage reference of the atmega. It is 1.1V or 2.5V depending on the exact model and it is usually more accurate than the 5V of an standard linear regulator. Just put an 100nF to ground on the Aref.

With the scope on the highest sensitivity it looks like your speech is picked up by the sensor and can be seen on the screen.

[qzorn]

very well explained... the 324 op-amp is very useful with lots of examples 😎 thanks this would be nice for simple load cells

[clickfix]

Cool! Analog signal conditioning is one of my favorite topics.
My first thought when i started watching this was that you where going to use an antilog amplifier (a circuit that uses the logarithmic voltage response of a semiconductor) but this is perfect when you just have a variable resistance, same technique is used for tailoring potentiometers, never saw that using an opamp before though.
I'd like to experiment with this my self, maybe you could eliminate the inverter using an antilog amp...

[DracoXul]

I really enjoy your videos .. love the tutorials .. I would also like to know what you are doing with all of the pressure sensors .. :)

[GeorgeGraves]

Really liked the video! Very helpful. It does make me wonder what kind of results you'd get by scaling the signal in software.

[mclovin]

Impressive video, but i still think you're greatest accomplishment is when you make aerogel that stuff is AMAZING should make video of you're larger pieces thanks

[byronwatkins]

A current source supplying the sensor in parallel with a resistor would also yield linear output voltage without requiring a negative voltage reference.

[IndustrialGoblin]

Nice tutorial for beginners!
What would those sensors will be used for in finished installation? (If you can tell this information, of course)

[robertobattiston]

Great tutorial and refresher from my EE classes! Thanks!

[sigepthuglife]

What a great video! Thanks for uploading. Question: At 8:30, you start to talk about low-pass filters because the force applied is "not changing, " so how would you construct a filter which forces are changing (sometimes rapidly and in small amounts)? Thanks in advance!

[tejonBiker]

¿Some reason to not use non inverting configuration?, with non inverting configuration you can use a zener as regulator for the sensor.

[nesnduma]

This is a very interesting tutorial. However in case one wanted a variable resistor to adjust the gain, I guess you could not put the filter in the op-amp loop and put it only at the op-amp output. In this case should a second op-amp be used as a buffer between the first op-amp and the RC filter?

[Sorzv]

Thank you for this video.. is it possible to get a diagram, showing how you connected the four sensors and everything together. am doing a weight scale with four sensors connected in series, and am lost on the connection part... please help

[bluegloves]

you might try the adhesive/epoxy used in auto glass repair