Design Open Source User Adapter

[SmittyHalibut]

Design a simple schematic and board layout for a generic User adapter that can be configured by the user for various different headsets.

Keep it simple, make it a good DIY project.

CC-BY, credit to OHIS. But allow commercial use and extension (read: not -NC and not -SA)

[SmittyHalibut]

Left to do:

• Finish up any more artwork on the main board?
  • CC-BY graphic?
  • Label the existing QR code
  • Add a version number tag to the board.
• Layout a top board
  • With hole for PTT button
  • Possibly with cut-out for RJ-45, if stand-offs are short enough.
• Layout an SMT version, or maybe add SMT outlines to the same board.
• Fill in BOM with Digikey/Mouser links, and LCSC links for the SMT options.

[SmittyHalibut]

Done:

• Ordered prototype boards.
• Ordered parts for 120 builds, to make 100 kits plus some prototypes for testing.
• The RJ-45 have tabs on the top that I didn't want exposed, so I went with a solid board on top, which requires 14mm spacers (13.4mm tall connector). I exposed the copper, put a solid box on the solder mask layer, so the tabs on the RJ-45 would connect with the board on the top layer. (It'll connect through the brass standoffs and screws too.)

Vertical stack up:

From top to bottom:

• M3 6mm screw
• 1.6mm: Top board
• 14mm: Brass standoff
  • 4.4mm of top screw: 6mm - 1.6mm
  • 3.8mm of bottom screw: 10mm - 1.6mm - 3mm - 1.6mm
• 1.6mm: Main board
• 3mm: ABS standoff
• 1.6mm: Bottom board
• M3 10mm screw

Spacing between the boards is 14mm:

• RJ-45 is 13.46mm tall
• Pin headers with jumpers are <10mm tall (measured 9.2mm, rounding up for slack.)
• 3.5mm sockets are 5mm tall.
• 2N3904 (page 8) is <10mm
• Capacitors (pages 5 and 22) are <6mm
• Resistors are very short.

Top surface of top board is 14+1.6mm = 15.6mm tall. The PTT button is 15mm tall, and the cap makes it 1mm taller, so 16mm tall. It will stick out through the top board by 0.4mm. Button travel is 0.25mm, so it will be MOSTLY flush with the top surface the whole time.

Just in case, I also just purchased some 16mm tall buttons to see whether they'll be a better choice.

[SmittyHalibut]

Oh! Also, check out https://open-headset-interconnect-standard.github.io/user-adapter/bom/ibom.html

[SmittyHalibut]

Notes from testing v1.0a prototypes:

• Artwork is wrong. Phones and Mic are swapped.
• Add a trim-pot to adjust the Mic level. The Radio Sport (electret) was just about right, but Heil Dynamic with the mic pre-amp was a bit hot.

[SmittyHalibut]

• v1.2 published, and ordered by Halibut Electronics.
• v1.3 changes added by Derek Rowland.
• Documentation for both added to repo.

This is done! Any future changes will be separate tickets.