RJ9 (4P4C) to 3.5mm Stereo plug frame

thingiverse

We required a handset jack (RJ9 4P4C) to 3.5 mm stereo plug conversion. We secured the connection using superglue and crimping the sleeve on the 3.5 mm plug, soldered the connections together, and applied heatshrink tubing to solidify the mechanical attachment. For a second installation at another location, we updated the design: we rounded off sharp edges, reshaped the plug mounting peg, and created a trough under the RJ9 while relocating the wire exit, resulting in a sleeker appearance. The first rendered image above depicts Version 2.1, which served as our initial reference. In contrast, the older version used in the assembly photos showcases the initial design approach. Important note: When repurposing old Nitsuko 124i/384i handsets, be sure to verify the wiring configuration of the RJ9 connector. Its non-standard coloring and pinout layout may cause confusion during installation.