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Yarn break detection circuit.

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gauravkothari23

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Hi all.
I want to make yarn break detection circuit usinh IR led
Can any body guide me for how can i develop the same.
I have tried using IR led's, as it works perfectly only when the yarn comes between the IR led, but at the time of vibration of yarn say appprox 3 to 4mm, it gives wrong indication. Min thickness of yarn is 0.1mm.
But i have seen some product in the market which are readily available and they works perfectly even if yarn vibrates.
I have even tried opening the case to check how they have done it, but it was completely filled with black color epoxy pudding.
 

Hi,

Afaik they often use linear CCD sensors.

But maybe you could try a reflection sensor, but you need very dark background.

Klaus
 

Hi,

Afaik they often use linear CCD sensors.

But maybe you could try a reflection sensor, but you need very dark background.

Klaus

They are using transmissive sensor, the same as image attached
 

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Hi,

intresting.

I wonder how they do this.
The yarn will reduce the transmitted light only slightely.
Thus any aging and dust may cause errors. This needs to be compensated.

Additionally I expect that the position of the yarn in the beam of light causes varying signal.

All in all I think this is a difficult task.

Good luck.

Klaus
 

Additionally I expect that the position of the yarn in the beam of light causes varying signal.

I wonder if this might be and alternative detection method. If there's a varying signal this would also indicate the yarn is still intact.
 

Hi,

If there's a varying signal this would also indicate the yarn is still intact.
Good point.
This makes sense.
It won´t work when the machine stands still, but maybe this is not necessary.

But when the machine works the sensor should read some AC signal.

Klaus
 

If you search " special yarn sensors- eltex of Sweden". There sensor produces a signal from the movement of the yarn and not its presence.

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Many of the detectors I've seen have small holes that the string passes through. Can you place a small ring over the yarn close to the sensor to minimize the distance the yarn can move when it vibrates.
 

If you search " special yarn sensors- eltex of Sweden". There sensor produces a signal from the movement of the yarn and not its presence.

- - - Updated - - -

Many of the detectors I've seen have small holes that the string passes through. Can you place a small ring over the yarn close to the sensor to minimize the distance the yarn can move when it vibrates.
No we cannot use any rings or any guide for the yarn... We need to develop touchless sensor for yarn
 

No we cannot use any rings or any guide for the yarn... We need to develop touchless sensor for yarn
Then you should refer to the other valuable suggestions made before.

Either dynamic detection utilizing intensity variation caused by moving yarn or static detection with imaging optics and CCD or diode array.
 

Can a capacitive sensor used or you need only IR?
 

Maybe you could give some more informations on the detector you made. Is it and emitter and detector without and enclosure. Are is it enclosed with a narrow aperture.
 

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