photoreflectors

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i am building a chess board traversing robot for my college fest.

i am not sure of what sensors to use.
i am confused whether to use IR-led and phototransistor pair or use a photoreflector.
please suggest

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What exactly do you want to do?

Michael.

User of:
IAR Embedded Workbench C/C++ Compiler
Altium Designer

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What is the distance between the face of the sensor and the surface of the "chess board" ?

The reason I ask is because I used a Sharp GP2S28 Reflective Photointerrupter (Digi-Key 425-1095-5-ND) to design a tachometer used to check a 20,000RPM motor. I used a round black Delrin "disk" mounted to the shaft of the motor. I covered half of the outside of the disk with white tape. The Sharp GP2S28 was mounted approximately 6mm away from the face of the disk. As the disk rotated the Sharp sensor would alternately see black and then white. I fed the output of that sensor to a comparator and the output of the comparator was fed to an input pin of the mega169 on a Butterfly. The output of the Sharp sensor was quite "sharp" (sorry, couldn't resist :-) ) with the transistions from black-to-white-to-black.

Regards,
Steve

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the distance between the chess board and the sensor would not be more than 8mm.

how good is the response time of photo interrupters?
what is the separation btw the ir emmiter and the photo transistor in it?

how much does each PI cost?
where do i buy it?

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Jeez Louise, all the information you are seeking is quite readily available on the Digi-Key website. Are you that new to electronics that you don't know Digi-Key? Even if you were are you not able to do Google searches? I gave you the manufacturer, manufacturers part number, a distributor for that manufacturer and the distributors part number.

I am done helping you because you don't seem willing to try to help yourself !!!

Okay, so now I have a deeper appreciation for Dean's frustrations. https://www.avrfreaks.net/index.p...

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Fill in your location. Maybe there are some freaks near you?

Imagecraft compiler user

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LED/transistor sensor pairs are designed for a fairly narrow sensing range. Omron makes them in a wide variety of sensing distances. Some of them are short range (5-10mm, I think) but you need to check, now that you have the info about where to look. They are easy to use; any engineering student that has taken a basic circuit design class should be able to handle it.

Speed is not super fast nor is is super slow. They tend to be slower turning off (light loss) than turn on. Turn on might be a few 10s of uS and turn off might be 10X more (numbers off the top of the head). This happens because the base junction is large in order to get the photo-sensitivity up, and that greatly increases the collector-base capacitance, if you care about such things.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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CNY70 fits the description almost perfectly. Although the guaranteed sensing range is a bit less, it will function even at 8mm.

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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but the cny70 data sheet specifies the sensing distance as only 0.3 mm

does it really work at 8mm?

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sorry steven for having foolishly asking all such questions.

i ll try finding out the vendors in india .

thanks

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Dopey question time,

Rather than using an optical approach, could you use a magnetic? a small magnet in the base of each chess piece and a reed switch in each chess square would be simpler, and cheaper than a photo option. Unless the idea is to have the robot position the pieces via user entered coordinates.

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

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i am building my bot for a competition where the chessboard is made of canvas!!

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Before you go too far, try and test your sensors on the actual chessboard, as not all things that look black are black to infrared. Some pigments are transparent to IR, so the sensor sees the color of what's underneath. If the competition specifies IR sensors it should be ok.

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thank you i will verify that

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Can you use the magnetic reed switch approach?

The canvas wont bother the magnetic properties. Your robot will need to remember which piece is where, unless of course as I asked earlier you are entering coordinates manually and the bot just moves the pieces

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user