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Audio to IR relay circuit question.

Discussion in 'Audio' started by roineust, Oct 29, 2015.

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  1. roineust


    Jul 2, 2013
    In the attached picture (please see below), you can see the schematics of an Arduino circuit i have assembled.

    It is a circuit that enables a smartphone, to switch On and Off electric devices. It works by converting an audio signal into IR pulses.

    Here is a link i used to assemble this circuit:

    My problem is this:
    Most of the time the circuit works well. But sometimes it gets stuck and does not respond.

    When that happens, i disconnect the upper left BLUE wire at "Disconnection point A" (please look at image) and then immediately reconnect it and things go back to normal and it works well again.

    Is there some kind of capacitor or diode or other electronic component that i can add to this circuit, which would eliminate that problem?


    Attached Files:

    Last edited: Oct 29, 2015
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    The audio amplifier delivers an AC signal.
    The IR transmitter has an IR-LED and therefore acts as a rectifier. The rectified current charges the output capacitor of the amplifier. Once charged, current can no longer flow and the operation of the transmitter stops.
    Try connecting a standard diode (e.g. 1N4148) across in reverse polarity across the LED (i.e. anode of 1N4148 to cathode of LED and vice versa).

    It also looks like you are not using the module correctly. It is intended to have 5V from Vcc to GND, then the data input to DAT. Therefore audio out needs to go to DAT and Vcc needs to be connected to 5V from the arduino.
    If the smartphone's signal is strong enough, you may be able to directly connect the DAT input to the smartphone's audio output and not use the audio amplifier at all.
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