Parts: 3.5mm stereo audio jacks

3.5mm stereo connectors for headphones and microphones are almost mandatory for audio projects. X1 (left) is a simple plug with connections for the audio channels (pin 2,3), and ground (pin 1). X2 (right) has pass-through contacts (pin 2,3) that divert audio to an internal speaker when headphones aren’t connected.

Here’s a breakdown of the audio connectors illustrated above. We found footprints for these parts, and several other SMD audio connectors, in the con-cuistack part library on the Cadsoft download page.

X1 3.5mm stereo audio jack (Mouser #161-3334-E, $1.16) This is a simple stereo audio jack with no internal pass-through. Fits footprint SJ-3523 in the con-cuistack library.

X2 3.5mm stereo audio jack with internal pass-through (Mouser #161-3335, $1.25) This is our favorite audio jack, but it looks like it’s going to be discontinued soon. Can anyone recommend an equivalent? Fits footprint SJ-3515 in the con-cuistack part library.

Don’t forget to check out our previous parts posts.


  1. starfight says:

    i need one of those… or 2…

  2. bearsinthesea says:

    I just bought a jack for my thingamakit, and the best feature was it had a metal screw-on collar and lock washer so it could be easily mounted on a box.

  3. CalcProgrammer1 says:

    I usually buy the ones at RadioShack, I don’t use surface mount stuff often. The RadioShack ones have screw-on collars so I used them to build a switch box for my speakers (hook up multiple audio sources to one set of speakers). I recently desoldered all the components off of a broken set of PC speakers, got a ton of capacitors, a few amp chips, and a few 3.5mm jacks.

  4. zach says:

    Not being an audiophile, can someone explain the point of a passthrough? It just seems superfluous…

  5. andrew says:

    has a lot more useful info

  6. Anyone know where I can get jacks and cables with 4 sections?

    the iPod as well as the Zune and other devices (like the DVD player in my car) use a 4 section jack to carry stereo audio+composite video….

    so far the only 4 section cables I’ve found are expensive break out cables that convert a 4 section end into normal RCA Audio and Video jacks at the other end.

    Having a single small cable with a 3.5mm plug on either end would be quite useful for a lot of projects, and especially those where you want to grab AV data from your portable media device.

    I’ve looked for these things for months but not found any resource that is terribly useful or economical for a hardware hacker. I figured this article is a perfect opportunity to as the h.a.d. community.

  7. along with my last post here is the pinout for 4 section connectors on the iPod, Zune, Camcorders and other devices:

  8. aonomus says:

    It would be nice to have part #’s on digikey/mouser for the popular ones, through hole parts that match the standard 0.1″ grid of holes in a perfboard/breadboard.

    Also part numbers for ones with screw collars, both metal jack body and plastic jack body (ie: sleeve isolated from case ground, and sleeve connected to case ground).

  9. PUNiSH3R says:

    Four conductor plugs:

    Available from

    Part # 171-7435-EX 3.5mm 4 Conductor Plug

    Part # 171-7425-E 2.5mm 4 Conductor Plug|0||P_SField|0

  10. Ken says:


    It’s so your device can behave differently when there’s something plugged into the jack. For example, automatically muting speaker output if you plug in headphones.

  11. PUNiSH3R, Thank you very much for that ^_^

  12. ryan says:

    they aren’t audiophile grade or anything, but they are inexpensive and they work. :)

  13. lwr says:

    As well as audio and power connectors, I’ve been known to use these as low profile RS232 connectors (3 sections = Tx, Rx and Gnd).

    Anyone else used these for something novel?

  14. cde says:

    4 Conductor 3.5mm jack to 3 rca cables are available at your local dollar store.

  15. MicrosoftBOB says:
  16. MicrosoftBOB says:

    Looks like it’s the same footprint, and even manufacturer too!

  17. @lwr – using this as a mini RS232 connector is an awesome idea, I can’t believe I didn’t thing of that, and I’m even working on a few projects where I needed a small sized RS232 connector!

    @cde – yes I know that 4 conductor to RCA are available in a lot of places (not my dollar store, though, already checked) but that’s not what I was looking for.

    4 conductor to 4 conductor patch cables seem rare as do 4 conductor jacks for projects, as do solder-able 4 conductor plug ends for custom cables.

  18. cde says:

    @ Twisted, you can check car audio/video places. I dd’d a 4 conductor plug to 3 rca JACKS, with weather proof cap from one once. You can go in and see if they have that.

  19. andygondorf says:

    I’ve used the passthrough contacts connected to a relay as an easy and unconventional motorcycle immobiliser.

    Stick the socket in an unobtrusive place on your bike/car dashboard, wire it into the ignition somewhere appropriate and the vehicle won’t move without a headphone plug inserted.

    Not hi-tech, but also not an easy to recognise system for most car thieves, therefore not easy to defeat.

  20. lwr says:

    That’s a neat idea. If you wanted to make it harder to defeat, I guess you could run some kind of serial protocol over it and query an encryption key embedded in a micro in a headphone jack.

    Or (analog and maybe more simple) put 3 resistors between the 3 jack contacts and use an op-amp circuit to detect that the resistor values are the correct ones for your particular key.

  21. Mike Lachance says:

    I have been looking all round and I can find it. I am wondering where I can get a 3.5mm phone jack (stereo) double open circuit/isolated switching “make” circuit.

    Refer to: (drawing XX)

    Thank you

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