Hi,
Any ideas how these digital calipers work?
They work with no contact and have better than 0.0005" step resolution and don't seem to miss a step during even very fast motion.
cheers, Jamie
Google is your friend.
Count pulses, capacitive sensor:
-- Jeff Liebermann snipped-for-privacy@cruzio.com
150 Felker St #D
Mmmmm... cheap linear encoders!
The better calipers are inductive rather than capacitive (coolant proof) and have absolute position encoding so they don't have to be reset to 0 every time they're turned on.
$200 for the nifty Mitutoyo inductive calipers. $20 for the cheapo Harbor Fright capacitive sensor flavor.
I think I can live with pushing the button.
However, I can offer a useful hint. The cheap calipers tend to arrive with ahem... cheap batteries, usually the Manganese Dioxide LR44 flavor. They don't last. Instead, I replace them with silver oxide SR44 batteries, which last much longer. The problem is that the dropout voltage for the electronics is on the high side. Alkaline drops in voltage on a drooping curve, while sliver oxide stays fairly flat, and then drops suddenly. While alkaline has more capacity (area under the curve), the voltage falls below the dropout point long before the silver oxide. There was a thread in sci.electronics.repair on the topic about 6 months ago. Also:
Overkill:
Capacitor instead of battery?:
Cheap silver oxide batteries:
-- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831-336-2558 # http://802.11junk.com jeffl@cruzio.com # http://www.LearnByDestroying.com AE6KS
Sure, Harbor freight...
Jamie
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.