Break beam IR emitter and detector

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Discussion Overview

The discussion revolves around the design and implementation of an infrared (IR) break beam sensor, including inquiries about suitable IR emitters and detectors, tuning frequencies, and circuit diagrams. Participants explore various sensor technologies and their applications, particularly in measuring speed and distance for bicycles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant requests a list of affordable short-range IR emitters and detectors suitable for a break beam sensor, mentioning a tuning frequency of 38KHz.
  • Another participant questions the need for a frequency-tuned setup, suggesting that a simple IR diode and a phototransistor or photodiode would suffice, but notes issues with ambient light interference.
  • A participant explains that pulsing the IR light can help filter out ambient light, allowing for better detection of the pulsing component, and mentions the availability of receiver chips designed for this purpose.
  • Links to resources and schematics for IR remote control modules are provided by a participant, which may assist in the design of the sensor.
  • One participant expresses interest in using the IR sensor for measuring speed and distance on a bicycle and welcomes further suggestions.
  • Another participant suggests using a Hall probe sensor with a rotating magnet as an alternative to the break beam sensor for measuring speed and distance, citing ease of implementation.
  • A participant shares their experience with break beam sensors used in a robot competition, indicating a preference for this technology despite challenges in sourcing Hall probe sensors locally.

Areas of Agreement / Disagreement

Participants express differing views on the necessity of frequency tuning for IR sensors, with some advocating for simple setups while others support more complex configurations to mitigate ambient light issues. The discussion remains unresolved regarding the best approach for the intended application.

Contextual Notes

Participants mention various sensor types and their functionalities, but there are no consensus definitions or established methods for the proposed designs. The discussion includes references to specific components and configurations that may not be universally applicable.

Who May Find This Useful

Individuals interested in designing IR sensors, particularly for applications in robotics or cycling, as well as those exploring alternatives like Hall probe sensors for similar measurement tasks.

Asok
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I need a list(data numbers) of short range IR emitter and detector(not very expensive) which can be used as a break beam sensor.. I also like to know what is the specific IC number which is used to tune the IR emitter's frequency which matches with the detectors receiving frequency. I have heard that the frequency is something like 38KHz.. If you guys can also give me a link to the circuit diagrams which I have to use for this, it will be a great help... :-)
 
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So you need a detector that detects if a beam of light is blocked? Why on Earth would you need to run it at some frequency. You take a stupid IR diode that cannot be tuned and anything like a photo diode, photo transistor or photo resistor and that is it.
There is hundreds of these things and no one will make you a list.
 
0xDEADBEEF said:
So you need a detector that detects if a beam of light is blocked? Why on Earth would you need to run it at some frequency. You take a stupid IR diode that cannot be tuned and anything like a photo diode, photo transistor or photo resistor and that is it.
There is hundreds of these things and no one will make you a list.

The problem is ambient light. If there is other light present, the simple LED to phototransistor setup will not work very well.

Pulsing the light from the LED allows you to filter out the steady light level and detect only the pulsing component of it. You can then use a lot of amplification of only this component.

38 KHz is commonly used as a pulsing frequency and there are receiver chips available for doing this.
They have a small lens on one surface and there is a filtering and amplifying circuit in the chip. Most TV receivers would have one of these for receiving the remote control.

They are available at large electronics stores.

You have to arrange the 38 KHz transmit frequency yourself but a 555 with an amplifier can be used for this.
 
hey guys... thank U so much... I was thinking of designing a device for measuring speed and distance of a foot cycle... Now I have nice begining... if you have any suggestions please post...
 
It would probably be better to use a Hall probe sensor switch with a rotating magnet on one of the bicycle wheels. This is easier than arranging light sources on a bicycle.

I have seen cheap "bike computers" intended for doing this. They sell in cycle shops for about $10 and feature a nice LCD display with various functions like speed and distance, lap times etc.
 
maybe you are right about hall probe sensors... I just had that idea of break beam sensors, because we had a robot competition recently in our university... and we used some break beam sensors plus some other sensors for the robot...our group got the second place... anyway i searched hall probe sensors in the local market(Sri lanka), but in here I couldn't find it... then I searched for its mechanical structure, but that was little too advance to construct... but your idea was brilliant on hall probe sensors, and I should work on it more and more, thank you and I'm waiting for your suggestions...
 

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