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### Topic: Measure distances in mm (Read 5717 times)previous topic - next topic

#### nmlfreitas

##### Oct 09, 2012, 07:18 pm
Hello guys
I'm not new with arduino and electronics, but i have a question that i need to ask to people that know a lot more then me.
I want to use a sensor with arduino to measure from 0.8mm to 6 or 8mm. I have a machine that is always working with wood sheets and i need to read the thickness of the sheets with the machine working, do you think it can be done with CNY70 optical sensor?
If not is there another sensor that can do it?

Thanks guys

#### CrossRoads

#1
##### Oct 09, 2012, 07:19 pm
Got a link tothe CNY70 datasheet?
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### pylon

#2
##### Oct 09, 2012, 07:57 pm
What accuracy do you need/expect? Is the surface of the sheets always the same (color, smoothness, etc.)?

#### nmlfreitas

#3
##### Oct 09, 2012, 08:33 pm
Thanks for the quick reply.
The sensor datasheet http://www.vishay.com/docs/83751/cny70.pdf
I need an accuracy like 0.8mm to 0.82 or 0.85 more less.

Thanks

#### CrossRoads

#4
##### Oct 09, 2012, 08:49 pm
Spec shows output will very from 0.1mA to 1mA, you'll have to take that use an op amp like this
http://www.dipmicro.com/store/index.php?act=viewProd&productCode=TLC279IN
to convert it to a 0-5V signal that the arduino can measure.
From Figure 11 the change in current between 0mm and 1mm is quite small.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### nmlfreitas

#5
##### Oct 09, 2012, 09:06 pm

From Figure 11 the change in current between 0mm and 1mm is quite small.

So that means if i want to detect changes from 0.8mm to 0.85 or 0.9 it will be hard or almost imposible right?
Any other sensor that it's possible for me to use?

#### Grumpy_Mike

#6
##### Oct 09, 2012, 09:30 pm
Yes you are asking too much from this sensor.
I assume you want a non contact sensor? It is quite difficult to do this and I don't know of any off the shelf sensors that will do this.
It might be possible to use a reflection of a laser onto a linear CCD sensor but it is not an easy setup.

#### CrossRoads

#7
##### Oct 09, 2012, 09:51 pm
You might be better with a mechanical dial kind of tool with digital output. Not sure what that is called.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#8

#### CrossRoads

#9
##### Oct 09, 2012, 10:11 pm
No, I mean something digital like one might find on an incoming-inspection table, or perhaps a calibraton table, for automatic recording of results.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### RIDDICK

#10
##### Oct 09, 2012, 10:32 pm
what about a webcam (properly affixed with screws or so... connected to some stable USB box... like an OLinuXino...) that looks at the piece from the side?
-Arne

#### nmlfreitas

#11
##### Oct 09, 2012, 10:42 pm
You mean something like this

http://www.microsense.net/products-position-sensors-selector-thickness.htm

?

A webcam to measure thicknesses??

#### RIDDICK

#12
##### Oct 10, 2012, 12:15 am
nope
not capacitive but optical...
or is it impossible to look from the side?
-Arne

#### nmlfreitas

#13
##### Oct 10, 2012, 12:38 am
yes i can be measured from the side if that is what you are asking.
But your are saying that the capacitive is not going to work for me?

Thanks

#### Nantonos

#14
##### Oct 10, 2012, 12:50 am

No, I mean something digital like one might find on an incoming-inspection table, or perhaps a calibraton table, for automatic recording of results.

This sort of thing?
http://www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=31761
plus USB interface
http://www.tormach.com/store/index.php?app=ecom&ns=prodshow&ref=31865

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