My second attempt at a breadboard adapter for using Thonkiconn-style 3.5mm mono jacks. These jacks can plug directly into a breadboard but they’re not very secure, so a breadboard adapter with more pins is a nice way to secure it. Also I tend to forget which pin is which when using other adapters that I’ve found.

This is based on little-scale’s similar board but I wanted a smaller board and labels for the connections.

There is a project page on github for this with kicad source files, pdf schematics, gerbers, etc. It’s for the newer version (V3) but is nearly identical.

BOM:

• 2 Thonkiconn jacks (QingPu WQP-PJ398SM or WQP-PJ301M-12, or compatible)
• 2 2x3 pin male headers

Changes from v2c to v2d:

• Everything is a little closer together.
• The board’s edges are a lot closer to everything.
• Because of those other changes, the board is a little smaller/cheaper.

Things to change/fix in future versions:

• Make the traces wider – I’m pretty sure they’re OK as-is, but why not make them wider since I have the room. (fixed in V3)
• Move the traces to the bottom of the board – Again, it’s OK enough as-is, but if they were on the bottom, then the labels wouldn’t be on top of them, warping the letters a little. (fixed in V3)

Render of the newer version:

(which is almost identical to this version)

Update 2020/04/17: This board has been tested and works great.