infrared sensor HOA0709

Discussion in 'Embedded Systems and Microcontrollers' started by samsoltats, Aug 14, 2010.

  1. samsoltats

    Thread Starter New Member

    Jul 13, 2010
    Hey someone out there, I am new into PIC programming and hobby designs, and i am currently trying to configure an infrared reflective sensor "HOA0709" to detect a black line. But i cant get it to work, the photodiode or should i say the transmitter side can switch on with 50mA, i have calculated the resistor before the IRED of 100 ohm but i cant get the sensor to work even just light the LED. it cant even switch the darlington transistor on as a result.

    May i please have help on this, i doing a line following robot with multiple input sensors. thank you.

    my email: <snip>

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    Last edited by a moderator: Aug 14, 2010
  2. Markd77

    Senior Member

    Sep 7, 2009
    How have you got it wired up? A schematic would be good.
    The datasheet seems to say that the on state collector current is 1mA which isn't much. Might be hard to see with some LEDs.
    samsoltats likes this.
  3. samsoltats

    Thread Starter New Member

    Jul 13, 2010
    Yes the collector of transistor needs 1mA from the driver side or IRED side, i.e. if infrared can't switch on deliberately the emitter side will get nothing to switch on. So as things stands the the photodiode"Ifrared side" needs 50mA to switch on, which implies 100ohm should be enough "according to ohm's law" but still does not work.

    As with the circuit, i am new to this forum i dont know how to attach a document here. but i have wired it up exactly as it appear on the datasheet, with addition of limiting resistor of 100 ohm at the anode side of the IRED and 2.2K ohm at emitter side of the darlington transistor to ground. and connected all the cathode to ground. thank you.

    I hope this makes sense, to make cognisance of it.

    Thanks for help though.
  4. bertus


    Apr 5, 2008

    As for how to manage attachments, this is in the FAQ:

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