Digital Vernier

Gentlemen,

ALDI's are selling Digital Verniers for £8.99 in a case with a spare battery, I've just bought one to put with my Van tools. It also has a very large digital display for us old un's

Martin P

Reply to
campingstoveman
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You can also find 100/150/200 mm length digital readouts that can be screwed to a slide . Makes a nice pseudo CNC type action if you get what I mean- advertised on EBAY about £20.

Reply to
TT_Man

"campingstoveman" wrote in message news: snipped-for-privacy@bt.com...

"Vernier" is a type of scale - see

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. I think you mean "Digital Calipers".

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for more info.

Reply to
MatSav

Iirc, digital calipers use the same mathematical principle as a vernier scale.

-- Peter Fairbrother

Reply to
Peter Fairbrother

Reply to
campingstoveman

Not any of the fairly large number of DROs, LVDTs and sundry gadgets I've worked on over the years, including the freaky Sony one that was a tube stacked with accurately sized balls.

Reply to
Andy Dingley

The Sony one sounds interesting.

Ordinary digital calipers have about 14-17 staggered rows of 4-6 metal strips on the circuit board, which combine with other metallisations in the plastic strip on the frame to form capacitors when they are in close proximity.

The spacing of the strips on the circuit board and in the plastic strip is such that there a small movement causes the capacitors formed to change, which is converted to a reading.

The spacing of the two plates is like the spacing on a vernier scale, in that it's not a whole number, and that fractional/vernier type spacing is what gives the scales their resolution.

It's a bit more complex than that, as instead of using just one point they use 7-10, but the principle is the same.

-- Peter Fairbrother

Reply to
Peter Fairbrother

Newall uses the same principle, I think.

Balls inna tube.

Cheers Trevor Jones

Reply to
Trevor Jones

Sounds like something the Spanish Inquisition thought up

Peter

Reply to
Peter Neill

It's Newall's patent, so if Sony are using the technique, they must be doing so under license from Newall or have circumvented the patent as an Aussie chap has done.

Mark Rand RTFM

Reply to
Mark Rand

Correction to that:- The patent has now expired.

How is it that Harry Webb feels that he should still be paid for work he did in the '50s, but manufacturers' work can be copied after a couple of decades?

Mar Rand RTFM

Reply to
Mark Rand

I wish that Harry Web had patented his 1950s work. By just doing cheap copyright he's still got it and us poor souls are still being given it. I still wish he would just 'Move it' Alan

Reply to
jackary

Ah, I see what you mean. Yes, I guess this would have to count as a vernier. It's a variant on the old "translucent ruler with a diagonal line" technique.

Reply to
Andy Dingley

I just took one apart.

I think it's just a simple vernier spacing rather than a diagonal, the diagonal arrangement is just to fit the pads in, as they would be too wide if they were in a single line.

There are 72 pads on the board, which is ~ 42 mm long. The pads on the bottom are 2.7 mm apart, so the 72 top pads cover 15 bottom pads, giving a resolution of 72x15 = 1,080 in 2.7 mm (that's the vernier bit), or 400 per mm.

This would be downgraded to 100 per mm for the metric readout, or converted to inches.

I have seen one before which is slightly different though, the pads were about 5 mm apart. I was surprised this time, thought they would all be the same.

-- Peter Fairbrother

Reply to
Peter Fairbrother

How does it work? Does it count the number of balls which pass a sensor, or do they act as parts of capacitors?

Best wishes,

Chris

Reply to
Christopher Tidy

That's perhaps a bit misleading, it's not a simple vernier. Think of it as doing 15 verniers simultaneously, each vernier having 72 possible values, with a slight displacement between each.

The scale then finds where the values of the 15 verniers change, giving another 15 x the resolution. It's kind of a double vernier.

I hope that's clear, I know what's happening but I find it very hard to explain!

-- Peter Fairbrother

or 400

Reply to
Peter Fairbrother

What has Cliff Richard got to do with digital calipers?

Reply to
John

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this is one......

Reply to
TT_Man

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