So I have a small amplifier that plugs into a 12V source and a standard 3.5mm headphone jack and plays pretty good sound to a 8ohm speaker. I am wondering if I can connect the 3.5mm headphone jack to an electret microphone and play the sound from the microphone out of the speaker. I guess I am wondering what kind of voltage the mp3 player outputs. Since that work great with the amp I guess I am wondering how to get an electret microphone to the leverl where I could input it into the same amplifier.

  • \$\begingroup\$ Microphone needs to be biased for proper operation. So you cannot directly connect a mic to your 3.5mm jack \$\endgroup\$
    – nidhin
    Jun 28, 2014 at 7:05
  • \$\begingroup\$ Related: I used it the other way around. I plugged headphones into a microphone jack. It worked, it wasn't perfect but it did the job as a maleshift solution. \$\endgroup\$
    – WalyKu
    Jun 28, 2014 at 11:39

2 Answers 2


The Op's question reminds of a tricky question paper :) . What I construde is;

  • 1) 3.5mm Jack= O/P (looks like an I/p).
  • 2) He wants to insert electret microphone into this jack .

But If he is listening to something with MP3 then the Jack is not an output device , he probably has an additional speaker somewhere ?? .If this is true then Jack is an I/P connector. The electret mic cannot be inserted directly, you need biasing as below . enter image description here

It would be better to add a pre-amplification stage as below;

enter image description here
from: here

When you plug into the microphone , slowly adjust the gain of your opamp and O/P volume of your amplifier such that feedback is eleminated.

  • \$\begingroup\$ What is R8 for? \$\endgroup\$
    – sherrellbc
    Jun 28, 2014 at 13:20
  • \$\begingroup\$ @sherrellbc, Thanks for pointing out that it probably might be a careless mistake . I have rectified it along with other site link. \$\endgroup\$
    – Adi
    Jun 28, 2014 at 13:34
  • \$\begingroup\$ Is it assumed that the mic in this schematic includes a decoupling capacitor at its output? Also, I have never seen a mic amplifier like this. Typically they are just common-emitted amplifiers. What is the purpose of C1 and `R3? It appears to be some kind of high-pass filter for the feedback loop? \$\endgroup\$
    – sherrellbc
    Jun 28, 2014 at 14:22
  • \$\begingroup\$ @sherrellbc, R3 and R4 sets the gain and C1 is there for providing ac ground to audio signal for this single supply preamp. \$\endgroup\$
    – Adi
    Jun 28, 2014 at 18:11

I am wondering if I can connect the 3.5mm headphone jack to an electret microphone and play the sound from the microphone out of the speaker.

No you can't. The headphone jack is an output; a microphone requires to be connected to an input so that it can be amplified.

  • \$\begingroup\$ While the wording of the question is not great, I think the OP may be referring to the 3.5mm headphone jack as being the input connector for an amplifier. \$\endgroup\$
    – PeterJ
    Jun 28, 2014 at 10:21
  • \$\begingroup\$ @PeterJ you may indeed be right. Time will tell. \$\endgroup\$
    – Andy aka
    Jun 28, 2014 at 10:29

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