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CupIRDistributionHardwareResearch  
Updated Oct 27, 2013 by rijadsul...@gmail.com

Research

Features using IR323/HO-A

  • Infrared LED IR323/H0-A
  • Peak wavelength λp=940nm
  • Max continuous forward current 100mA
  • Typical radiant intensity at 20mA continuous current 3.5mW/sr
  • 60˚ beam angle
  • Performance graphs can be seen on datasheet

Features using 2N2222A

  • 2N2222A NPN switching transistor
  • Max collector current 800mA
  • Min transition frequency 300MHz
  • Max emitter-base voltage 6V
  • Three terminal through hole
  • Included in circuits lab kit
  • Performance graphs can be seen on datasheet

Circuit Diagram

Simulation Results

  • Green is 5V 56 kHz square wave
  • Red is BJT emitter voltage

Distance Equation

The maximum distance the IR needs to travel is 1.5 meters. The maximum current needed can be calculated using the equation below.

  • I_e=emitter intensity
  • Emitter intensity of IR323/HO-A at 20mA: 3.5mW/sr
  • E(e,min)=irradiance of the reciever
  • TSOP36256 minimum irradiance (56 kHz) (receiver on the headband) when Vs=3V
  • Pulse width tolerance: t pi- 5/fo< tpo< tpi+ 6/fo. Typical: 0.4W/m2
  • d_max=maxdistance = 1.5 meters
  • Using the above information, the maximum current needed is 5.145mA
  • Therefore, if there are 9 IR LEDs mounted on the cup, the total current used by the system is 46.3mA

Block Diagram

Alternatives

Features of MTE9440M3A

  • Peak wavelength λp=940nm
  • Max continuous forward current 60mA
  • 160˚ beam angle
  • Through hole
  • $3.00 each

The reason we didn't use these is because they are $3.00 a piece.

Features of IR25-21C/TR8

  • Peak wavelength λp=940nm
  • Max continuous forward current 65mA
  • Typical radiant intensity at 20mA continuous current 1.5mW/sr
  • 160˚ beam angle
  • Surface mount IR LED

It would be more difficult to mount surface mount components on the outside of the cups.

Features of ZVN2110G

  • N-channel DMOS FET
  • Max collector current 500mA
  • Fast switching speed
  • Max gate source voltage 20V
  • Min gate source threshold voltage 0.8V
  • SOT 223 package
  • Pulse drain current 6A
  • Fall time 8ns
  • Rise time 4ns

I didn’t want to use a MOSFET because I am more familiar with BJTs.

Features of BC817

  • NPN general purpose BJT
  • Max collector current 500mA
  • Min transition frequency 100MHz
  • Max collector base voltage 50V
  • Max emitter base voltage 5V
  • SOT 323 package(surface mount)
  • Pulse drain current 1A

Suitable replacement of 2N2222A if it fails for unforeseen reasons.

References

  • 1. Discrete Semiconductors, “2N2222; 2N2222A NPN switching transistors,” 2N2222A datasheet, May 1997.
  • 2. Everlight, “5mm Infrared LED IR323/H0-A,” IR323/H0-A datasheet, May 2013.
  • 3. Vishay, “Standard Thick Film Chip Resistors,” D/CRCW e3 datasheet, June 2012.
  • 4. Everlight, “Technical Data Sheet Reverse Package Infrared LED,” IR25-21C/TR8 datasheet, Nov. 2005.
  • 5. Marktech, “Infrared Emitter,” MTE9440M3A datasheet, Aug 2011.
  • 6. Diodes Inc., “SOT223 N-CHANNEL ENHANCEMENT MODE VERTICAL DMOS FET,” ZVN2110G datasheet, Oct. 1995.
  • 7. NXP, “BC817; BC817W; BC337 45 V, 500 mA NPN general-purpose transistors,” BC817 datasheet, Nov. 2009.
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