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It is possible to use audio jack output to give power to a microcontroller?
How many milliAmperes it feeds?

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  • \$\begingroup\$ I know that in general case it's possible and I've seen USB devices connected using TRRS. \$\endgroup\$
    – AndrejaKo
    Commented Mar 8, 2012 at 10:26

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You have somewhere between 100 and 500 microamps according to the OMTP Local Connectivity Wired Analogue Audio specification.

The electrical characteristics of the audio Terminal of the Terminal SHALL operate within the values stated below: Bias Current Min 100 µA Max 500 µA (Voltage of 2.1V generated over microphone component with serial pull up resistor value between 1.90 kΩ and 2.2 kΩ) Usage sensitivity Min -62 dBV The measurement of the electrical characteristics SHALL be done in accordance with the standard publication IEEE Std 269-2002 [4]

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  • \$\begingroup\$ These specifications are for the input signal, not for the jack itself. It would make no sense for a terminal to have a minimum current requirement. This simply defines that a jack must be capable of handling at least 500 µA, in fact, it must handle more than 500 µA. How much more isn't defined here, but I suspect that it's a good deal more, closer to the ~100 mA rating of the fine-gauge wire in the audio cable. But I don't have a reference for that, and you do, so +1! \$\endgroup\$ Commented Apr 12, 2012 at 13:21
  • \$\begingroup\$ Clearly someone needs to chop open a TRRS cable and put an ammeter between the audio meter and ground. \$\endgroup\$
    – joeforker
    Commented Apr 12, 2012 at 14:36
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    \$\begingroup\$ @KevinVermeer I think the spec is actually saying something subtly different: It's saying that the terminal will apply a bias potential of 2.1 V between two pins for a condenser mic, and that it must be capable of supplying at least 100 uA into the load, but that it doesn't need to supply more than 500 uA. Also, this appears to be a bias current spec, so these are average currents (over probably some 10's to 100's of milliseconds), and the mic current is high-pass filtered for audio use. \$\endgroup\$
    – nick g
    Commented Sep 18, 2013 at 18:10
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It is possible to use audio jack output to give power to a microcontroller?

Yup it is possible.

Consider you are having TRRS audio jack pin. Now, when the output signals come to Left or Right audio pin, you can harvest that voltage and use that

This link may help http://web.eecs.umich.edu/~prabal/projects/hijack/

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