Awesome topic! These things do amaze me. Even a $5 caliper you whip in and out as fast as you can and it somehow doesn't lose any steps

The patent that explains everything. US5731707. Crude PWM to make psuedo "sinewave" equivalent (FIG2a-g) that moves along the length but constantly flip's a demodulator to avoid negative voltages that goes into an integrator circuit (Fig 14) to accumulate charge every time the next psuedo sinewave. This all results in a sinewave that appears to be moving across the 8 emitters and it's searching for where the capacitive plate that is coupled has no charge because it's balanced by the finges producing a sinewave over the 8 terminals that results in an even voltage. This is cap coupled to the moving bit, back to the large plate. The whole system is basically looking for the "zero" cross. but even with the pwm like psuedo sine wave it's not too acurate. It's original design used a 6bit ADC to get about 10 micron accuracy I believe or maybe 1micron?. Commonly misunderstood to be capsense and it's not, certainly if it did the small relative in-out motion of the slide would throw off readings. The actual capacitance value means precisely nothing, just needs sufficient to couple through. The fun thing is that a 20 dollar Amazon special and a 200 dollar Mitutoyo only differ in physical material quality and low power when screen is off. There are other sensing arrangements Nils Andermo invented that may be more accurate and yet nobody uses them.

Nice video. I like the way you immediately get into the details and don't waste time.

Dropping acid is also my favourite part whenever i take apart old electronics to study them.

So, even digital works on the vernier principle. Great content.

this is a stunning video! i really enjoy the level of detail and method you go into

Interesting teardown! I was expecting a little encoder wheel like on a computer mouse, but more precise. The linear design makes more sense.

Fantastic teardown. I have one of these cheap units and wondered how they achieved such accuracy.

At first I was sceptical of plastic, but for 5$ you can get pretty precise device. Certainly better than a mechanical ones where you cannot see a damn thing. And very convenient to use.

Awesome video mate, I've learned a lot thank you! Subscribed :)

Cool 👍

Seems to me like the capacitive equivalent of the magnetic resolver.

I bet the stuff in the upper right is memory (ROM+RAM) for a small CPU, if even a 4 bit one.

The simplicity of design, incredibly low power of operation, extreme precision (I am able to repeatably get near single micron accuracy from them), and robustness of the measuring mechanism to mechanical shock and wear of these devices is astounding. I am amazed every time I have to use one at work.

another electronupdate video!!!!!!!!

Great video. So the question would be, could you tell absolute position on an XY rail by just creating a PCB that lays on the rail with the wider fingers and then let the board with the smaller fingers just ride along the carriage on the rail? This would be a great way to create a closed loop system, but it doesn't seem like folks do that too often. If you look at linear motors for instance, they tend to use plastic strips along the rail with tiny black lines, and then just pick up light passing through the plastic or getting blocked by the black ink. This leads to a further question that these calipers do seem to know their absolute position, not just relative, albeit you do have to zero them. So perhaps they are just relative and the battery makes them feel like they're absolute because they just always watch for the movement which is why the battery dies on these after about a year.