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Amplifier the smartphone headphone port voltage

Discussion in 'General Electronics Discussion' started by Yasas Weerasinghe, Nov 20, 2018.

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  1. Yasas Weerasinghe

    Yasas Weerasinghe

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    Nov 20, 2018
    My phone doesn’t have IR feature, so I create a IR blast and to increase the working distance I need more power to IR LEDs.

    So is it possible to increase the headphone port power?

    If it’s how?

    Thankyou!
     
  2. Audioguru

    Audioguru

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    Sep 24, 2016
    Feed the headphones output from the phone into the input of a more powerful amplifier. Then the IR LEDs might be destroyed.
     
  3. Yasas Weerasinghe

    Yasas Weerasinghe

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    Nov 20, 2018
    Yeah. It might be. The thing is the headphone voltage is not enough for the IR LED. So is there a way to increase voltage between 3.5v to 5v?
     
  4. Audioguru

    Audioguru

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    Sep 24, 2016
    If you have an external 5V power supply or battery then a single transistor can amplify the 3.5V to 5V.
     
  5. Yasas Weerasinghe

    Yasas Weerasinghe

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    Nov 20, 2018
    What you saying is ‘give an external power to the audio jack (IR LED connect to audio jack)’ right?

    If it’s you're saying, isn’t that damage the phone when external power goes in the phone through the headphone port?
     
  6. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    You don't apply external power to the audio output of any device.
    You need an amplifier, possibly a very simple one as @Audioguru has suggested.

    What is the "IR blast" you created? Show us your circuit diagram. We may be able to make better suggestions.
     
  7. Yasas Weerasinghe

    Yasas Weerasinghe

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    Nov 20, 2018
    This's what I did
     

    Attached Files:

  8. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    That won't work, as you have already noticed. Use a simple amplifier (see my previous post) and an external battery to boost the signal.
     
  9. Alec_t

    Alec_t

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    Jul 7, 2015
    What will you use to receive the IR signal? If it's a gizmo with an irDA port then the signal you send to it needs to be a digitally coded one, not the analogue one available at the headphone output of your phone.
     
  10. Audioguru

    Audioguru

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    Sep 24, 2016
    The plug for the headphones has 3 connections but you do not show which 2 connections you used.
    The tip and ring are Left and Right channels and the sleeve is the ground for both channels.
    An LED works from DC current but the audio has no DC, it has AC.

    The single transistor amplifier I mentioned is powered from the external 5V. The audio from the headphone jack on the phone gives AC signals to the transistor. The transistor amplifies the signals.
     
  11. BobK

    BobK

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    Jan 5, 2010
    IR LEDs are typically around 1.5V, not 5V.

    Bob
     
  12. Audioguru

    Audioguru

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    701
    Sep 24, 2016
    He does not show which two pins of a 3-wires stereo plug he has the IR LEDs connected to and does not show a schematic to show if they are connected with opposite phase. No current-limiting resistor is shown so maybe they are already burned out.
     
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