twist sensitive resistor?

I have science project that involves measuring a small torque, or twisting force.

Is there a torque sensitive resistor I can buy? Or perhaps a torque sensitive capacitor? I can integrate it into an existing circuit if I can find one.

Thanks, Dave

Reply to
Dave
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Reply to
ChadMan

That will measure angular displacement (which may be an analog to torque), but it doesn't measure force or radius. . . Please don't top-post.

Reply to
JeffM

Next time you post to multiple groups

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post just ONCE and put ALL the groups in which you want the question to appear on the Groups line.

This allows EVERYONE who reads the question to easily see ALL the solutions that are proposed. . . . Henry has already suggested a variable capacitor.

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That can be an analog of torque (as can a potentiometer--which is smaller and cheaper). Both of these will likely require gearing to get any kind of resolution (leaving you with forward/backward lash). . . A strain gauge measures force (which can also be an analog of torque).

Reply to
JeffM

google 'strain guage' or 'piezo-resistive'.

HTH

Reply to
Randy Day

You could make a capacitor to be torque sensitive. Attach one plate to the shaft and the other to a fixed point. The capacity will vary with the torque.

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Hank WD5JFR
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Reply to
Henry Kolesnik

One of our machines at work has an optical pick up on on each end of a drive shaft. when the machine is at idle (no torque) the 2 opticals are perfectly aligned or near it. as the shaft starts to twist under load, the drive side will get ahead of the output side of the shaft thus causing the two opticals to miss align and produce an offset of pulses ect./

also you could simply measure the load current on the drive device? there are also things like load cells that use a capactive method.

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Real Programmers Do things like this.
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Reply to
Jamie

How small is the torque? The magnitude such as between two small, balanced and suspended masses and another pair of masses as in the Cavendish experiment?

What is twisting? If it is the famous dumbbell experiment, for example, you can just use a simple small-milliwatt 635nm diode laser or better yet a HeNe laser and bounce it off of a tiny bit of mirror attached to one of the suspended masses. You can easily align the beam so that it reflects and then hits an exact point on a distant ruler and when the suspended mass shifts slightly through some angle X, the reflected beam will go though a deflection change of 2X. This may be just fine if you are replicating Cavendish for a science project.

Jon

Reply to
Jonathan Kirwan

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