Spring 2016: 3DoT David IR Trade-off Study

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IR Emitter/Receiver Study

Introduction:

This is an overview of the trade-off study conducted for the selection of our IR emitter/receiver system. We will being going over the characteristics of each component that were taken into consideration while gathering information, as well as solutions to creating the ideal IR system. In addition, there is a link in the resources section that we used to understand the datasheet specs.

Note: There were no actual specifications for the IR system. The following results are what we believe to be the most optimal for our project.

Emitter:

Ideal Characteristics:

  • The IR emitter we choose should have low input voltage (2V~3V) to consider low power consumption
  • As narrow a beam angle as possible (10 degrees ~ 20 degrees) for increased accuracy
  • Cost efficient for DIY hobbyists ($0.75 ~ $2.00)

Results:

IRTradeOff_SFH 310_BlogPost

Screen Shot 2016-05-04 at 10.22.34 PMFig. 1: Table of appropriate IR emitters)

Receiver

Ideal Characteristics:

  • The range should not be greater than 2m (6ft) in order to meet the subsystem reqirements.
  • Wide directivity (receiving angle) around 100 degrees ~ 180 degrees so it can be hit from all angles
  • Cost efficient ($0.50 ~ $2.00)

Results:

Screen Shot 2016-05-04 at 10.22.01 PM

(Fig. 2: Table of appropriate IR receivers)

Conclusion

  • On the emitter side, it would be wise to consider using the SFH4545 because it has a beam angle of 10 degrees, can handle up to 1A (motor driver goes up to 1A), has an average current of 100mA, only needs 1.5V for supply, and is only $0.62.
  • On the receiving end, the best choice would be the TSMP77000 because it has the lowest range of all the receivers (5m), has a wide directivity (100 degrees), and is only $0.69.
  • There is a helpful link in the resources section that explains how to create your own lens tube for improved accuracy and range.

Update:

Kent was given a SFH310 for the detector and a NTE30047 for the emitter in order to test how each component was working. The beam angle is a bit wider on the emitter he was given but it will work fine for our game of tag when combined with a lens. The purpose of the lense is to increase the overall range and increase the accuracy of the emitter. See the IR/Emitter blog post to see my research on the effect of lenses on IR emitters.  The lenses have yet to arrive, but when they do he will begin testing to see if the range increased and determine what the voltage rating is at the further distances.

Resources:

Understanding Diode Ratings | http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/diode-ratings/

DIY Laser Tag |  http://www.lasertagparts.com/mtoptics.htm