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4 circuit TRRS 3.5mm plugs - how to wire?

Discussion in 'Homebrew and Kit Projects' started by KC8QVO, Feb 29, 2012.

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  1. KC8QVO

    KC8QVO Ham Member QRZ Page

    I got a bag of 4 circuit TRRS 3.5mm coaxial plugs from Mouser and I am a bit unsure of how to wire them. The plugs have the standard ground/sleeve that also acts as a strain relief when crimped over the wire, but they don't have the standard solder terminals inside. The terminal for the last ring is a very thin rectangular protrusion and the tip and first ring are "pins", one inside the other with dilectric in between. The amount of the metal exposed is very small and not easily soldered to.

    Any ideas on how to use these?
  2. KK4FUS

    KK4FUS Ham Member QRZ Page

    Are you talking about these, or something worse?

  3. W9GB

    W9GB Ham Member QRZ Page

    Steve -

    Did you know that Mouser sells these connectors as "pigtails"? (part of pre-made cable assemblies).

    Kobiconn makes these in 3 and 6 foot lengths with 3.5 mm TRRS already soldered : Mouser, part number: 172-7447-E
    Cables (Cable Assemblies) 3.5MM 4 COND R/A PLG 72" BLACK/STRIP/TIN $4.77 each

    73, greg
    Last edited: Feb 29, 2012
  4. KF5FEI

    KF5FEI Ham Member QRZ Page

    On the pigtails and pre-built cables, you have to watch which one they connect as common or shield. Some devices (like the iPhone) don't use the ring closest to the housing as ground. And some of the radios (like the FT-60) don't have room for a connector with a large diameter flange -- I had to taper down the molded plastic on one with a deburring wheel to get it to plug into the radio all the way.
  5. KC8QVO

    KC8QVO Ham Member QRZ Page

    That is pretty much what I have.
  6. KE3WD

    KE3WD Ham Member QRZ Page

    Cut the wires and strip to exact lengths needed.

    Twist stranded wires, then TIN each one with solder first.

    Sometimes helps to also TIN the connection points as well.

    Tiny iron tip, good amount of heat so you can get in and get out, place a tinned wire on top of a tinned contact and apply heat with tip of iron on top. Just long enough to let the two tinned solders flow. Get in and get out. Keep holding in place until the joint hardens. Move on to the next one, etc.

    Magnifier can be a big help here.

  7. KK4FUS

    KK4FUS Ham Member QRZ Page

    It's not that hard to solder once you have proper tools and some soldering skills.

    First, tin the contact pads. You have to do it very quickly so:
    a) the plastic insulator won't have time to melt;
    b) you will have a layer of flux remaining on the pad.

    Then strip and tin your wires. Again, the quicker the better, for the same 2 reasons as above.

    Trim the wires to make the exposed conductor the same size as the contact pad.

    Now solder the wires onto the pads. Once again, the keyword is "quick". One single touch of the iron, just long enough to melt the solder completely. Hold the wire steady while the solder is hot.

    Oh, and the most important thing.
    Don't forget to put the connector cover onto the cable before you solder it if the other end of the cable is already wired! It gets me every time. :mad:

    P.S. About the "right tools"... Your soldering iron must have a fine tip. Temperature adjustment is highly recommended. The solder should be rosin core type, reasonably thin (1/32" or so in diameter).

    When you gain enough experience, you will be able to solder TSSOP chips using a 3-pound 200W soldering gun with a 1/4" wide tip. Until then, you should start learning with proper tools.
    Last edited: Mar 1, 2012
  8. KF5FEI

    KF5FEI Ham Member QRZ Page

    That is step 5 -- cut the cable off the connector, slip the cover on the cable, and repeat steps 1-4.:p
  9. K8ERV

    K8ERV Ham Member QRZ Page

    My camcorder and new Chinese Wonder HT are like that. The ground is the ring next to the shell.

    Does any one know why?

    TOM K8ERV Montrose Colo
  10. AF6LJ

    AF6LJ Premium Subscriber QRZ Page

    That's simple Tom;
    To keep you buying accessories from them.
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