Digital Caliper Interface?

[elektrinis]

Last time I checked, you could also by these as standalone encoders, i.e. same module on a slide, but without the caliper head. They came with mounting brackets for each end instead. I used a couple on a lathe project many moons ago.

This is interesting. I was searching for a module, but could not find any. At least cheaper than $3 caliper...

I consider making my own PCBs. Does anyone have a schematic/layout of the sensor and knows what kind of chipset it uses? Perhaps it could be done with any of those $1 micros with capacitive touch inputs?

[kosine]

Search term is "digital linear scale". Even though they use the same hardware as the calipers, they are quite a bit more expensive. (Economics of supply & demand, I guess.)

Not sure how easy it would be to make your own. Ultimately you only need the long PCB the module slides on, but that might take a bit of trial and error to get right. Making the module as well sounds like a bit of a challenge.

When you factor in your time & effort making it work, it might not be worth it. For under $50 you can just buy-in a solution, or cut the end off a cheaper caliper.

Might be fun to strip one right down and see what makes it tick, though. Maybe there's a video out there already.

[elektrinis]

Yes, for now I have just stripped my calipers. This is for a highly integrated solution, so may think about making custom hardware later, could be a fun project.

[cdev]

Could be useful for making a digital X-Y table for drilling the vias on PCBs.

[6PTsocket]

A power on is defined by sticking a battery in. These cheap calipers never actually turn off, they just turn the LCD off.

Most all digital calipers go to a low draw sleep mode when turned off. Many of the cheap calipers use the same microcontroller, even the same board in some cases. All of mine use the same board, and there are a pair of redundant buttons on the board so it will fit into many different models. I believe AvE, or maybe one of his viewers, measured the sleep current in a HF caliper and it is 4x the draw of a Mitt.

But the biggest difference is the battery. Mittutoyo come with a silver oxide battery. I put Energizer silver oxide cells in my cheap calipers, and they last over a year. But don't buy the cheapest batteries you can find. I tried some generics, and they lasted 3 months. I measured the cell voltage on them, and I got 1.588, so I'm pretty sure they're alkaline. A true silver oxide is 1.550 on the button, when new.

They are completely interchangeable but the silver oxide last longer and have a flatter discharge curve, ie, they stay near full voltage until the end as opposed to alkaline that that gradually drop  to an unusable value as they are used up. There are a lot of interchangable numbers for each. Silver oxide is SR44, 357, 303 plus others. Alkaline is LR44 and a bunch of other numbers. Easily looked up. Be careful; some sellers list alkaline cells as replacements for silver oxide.The reverse is OK as the silver oxide is better in all respects. Either type is easily found but the silver oxide a several times more expensive. Dollar Tree has the LR44 alkalines at 4 for a buck.

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