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IR diode minimum resistance — Parallax Forums

IR diode minimum resistance

Eric at Sac StateEric at Sac State Posts: 8
edited 2009-05-13 19:27 in Robotics
I have been looking over the robotics manual, and while a 1K resistor is given as the value recommended for the IR diode, it also seems to suggest that the IR diode might burn brighter, but not burn out, if it was given a lower value resister for example a 220?

The actual text experiment is with a LED not an IR diode?

Comments

  • SeariderSearider Posts: 290
    edited 2009-05-13 18:39
    Eric,

    The resistor is to limit or control the current that flows through the Diode. You need to use the basic OHMs law to calculate the resistance that you need given a specific voltage drop

    E=I*R

    Voltage supply less voltage drop of the Diode· = E
    I is the current that you want. Less than the max allowed current in the diode's data sheet
    R is the resistance that you should use.


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    Searider
  • Jessica UelmenJessica Uelmen Posts: 490
    edited 2009-05-13 19:27
    Hi Eric,

    Take a look at the Stamps in Class "Mini Project" Better Boe-Bot IR Distance Measurements. It demonstrates how to use different resistor values for different IR LED brightnesses. I hope it helps!

    Jessica

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    Jessica Uelmen
    Education Department
    Parallax, Inc.
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