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Discussion in 'Sensors and Actuators' started by BHEKI, Nov 10, 2014.

  1. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    You should run the IR LED at the current recommended in the data sheet. If in doubt, try 20 mA. IR LEDs have a forward voltage of around 1V so calculate your series resistor using Ohm's Law to give the desired current with (power supply voltage minus 1 volt) across it. For example if your power supply is 12V and you want 20 mA to flow, calculations would be:

    R = V / I
    = (12 - 1) / 0.02
    = 11 / 0.02
    = 550Ω.
    Closest preferred value is 560Ω.

    Yes you can use any small-signal PNP Darlington transistor, or you can connect two small-signal PNP transistors (e.g. 2N3906) together in a Darlington connection (see
  2. BHEKI


    Aug 28, 2014

    Thank you for this information,im grateful
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