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Fifth generation of iPhone. Repair of this device is straightforward, and requires screwdrivers, prying tools, and patience. GSM/CDMA / 16, 32, or 64 GB / Black or White.

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what's the iPhone 3.5 mm output jack power supply output?

Hey - I am trying to understand what's the power (watt) that the iPhone 4s (or iphone 4) can push from the 3.5mm output jack...

I THINK it's voltage output is 1.5v (I would be happy to get confirmation on that) , but I have no idea about the power it can drive..

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geva, start checking on here and if you have an oscilloscope, you can measure it by following this link Great question...


I would like first of all , to send a BIG THANK YOU to you both for answering my question :-).

I want also to clarify my question , since now that I read your answers, I understand better what to ask :

1. I want to use the iPhone 3.5mm to connect a microphone , but I need to understand the power concumption this microphone can take from the iPhone - since the iPhone powers the original iPhone headset microphone, I assume it can also power other types of microphons, but not all types, just the ones that operates on the same power concumption of the headset mic - so, what is it?

2. question about the iPhone 4s INTERNAL microphone - can you supply the full spec details of the iPhone intenral microphone?

Thanks again for all your help :-).



@geva, for a microphone you are actually looking at impedance. Microphone Output Impedance: Long = 1700 Ohms (at 1000Hz) and Short = 760 Ohms (at 1000Hz) (It is very important to note that the iPhone 4 internal mic input requires a mic with an impedance of 800 Ohms and higher. The biggest reason for other iPhone external mic's not to work is an impedance mismatch. Here is all you ever wanted to know about using an external mic


@oldturkey - thanks again for your help and detailed knwoladge (I am really impressed!)

If you be kind enough to add to this thread the details of a technical spec analysis of the iPhone INTERNAL microphone (just like you did for the headset microphone) , it will help me a lot.

Thanks ,



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The audio jack is actually a 4-pin connector. The additional pin is for the mic input.

1 Tip Left audio

2 Ring Right audio

3 Ring Common/Ground

4 Sleeve Microphone

Since the iPods have some 60mw output (30mw per channel) I would put the iPhone into that range.

Here is some other audio data comparisons:

Frequency Response iPad2; iPhone4; iPod classic 6th;

(from 40 Hz to 15 kHz), dB: +0.04, -0.55 ; +0.02, -0.16; +0.03, -0.18;

Noise level, dB (A): -90.3; -90.2 ; -90.2;

Dynamic range, dB (A): 90.2; 90.2; 90.2;

THD, %: 0.0045; 0.0068; 0.0049;

IMD + Noise, %: 0.0098; 0.012; 0.010;

Stereo crosstalk, dB: -49.2; -72.4; -67.5;


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Yes, 4 contacts....I thought so. 60mW total audio signal power.

But it doesn't source DC operational power to external equipment.

The original poster's question looked like that was what he meant.

Thx for the clarification.

I've often wondered which contact is used for the FM radio antenna

on an ipod nano....happen to know? That's a pretty tricky setup

using the headphone wires as an FM radio antenna.


@cns..."All wires receive radio signals, and depending on the configuration and length they are better or worse than other wires. In the case of the nano and similar FM radios that use the headphones as antennas, they use filters to couple the captured RF from the headphones into the FM receiver. The filters usually consist of inductors and capacitors and permit only the RF energy to enter the FM receiver, while blocking the speaker output from the audio driver. The audio driver may have similar filters that block out the FM energy from the audio driver. The speakers are natural filters - they won't react to signals much above 20kHz, and the radio RF is too small to make a difference even if they did perform at 95MHz." I go out on a limb here and bet that ground will carry most of it, and would be the wiser choice to reduce interference


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The headphone jack on an iPhone 4S does not supply power.

It has 3 contacts. It supplies left/right audio and a control signal

and has a ground.

It does not supply power in the "power supply" sense of the term.

One cannot power other equipment from the headphone jack.

It does supply a certain amount of power - audio power - measured

in milliwatts, I believe. But that cannot be used to power another mp3 player

(for instance) with operating power. But the audio signal can and will

drive an amplifier that gets it's own operating power from it's own

internal power supply.

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The headphone jack does indeed supply power:


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" The HiJack energy harvester can supply 7.4 mW to a load with 47% power conversion efficiency when driven by a 22 kHz tone from the output from a single audio channel on the iPhone 3GS headset port"

So tell me how the headphone jack on iPhones can't supply power? The question wasn't "can the headphone jack power a mp3 player".

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Seth Ludeman check on this question


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geva zal eeuwig dankbaar zijn.

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