General Aviation Headset to USB Adapter Enclosure

General aviation headset microphones can't directly be used on a computer for two reasons:

• They need amplification
• The 3/16-inch phone connector for the microphone (PJ-068) isn't commonly found in other applications

My David Clark H10-13X also has electronic noise cancellation which needs 9 V to work.

This adapter takes care of both and puts it all in a user friendly package.

I printed both the jig and enclosure in ABS for its better temperature resistance compared to PLA, e.g. for transporting in a car; if printing ABS isn't an option for you PETG is likely the better choice for open air printing.

Bill of Materials

• Switchcraft 12B 1/4" Stereo Headphone Jack
• Switchcraft S12B 3/16" Microphone Jack
• USB 2.0 cable
• CKCS BS01 MT-3608 DC to DC Boost Converter (i.e. an 11.2 x 22.2 mm PCB that can do 5 to 9 Volts DC boost)
• 20 mm x 20 mm LM386 electret microphone amplifier board (preferably with an adjustment potentiometer)
• Sabrent USB sound card
• 3 mm wide or smaller “zip” cable tie
• 4 x M2x4x3.2 mm threaded brass inserts
• 4 x M2x8 flat head cap screw (FHCS)
• 2-pin JST XH vertical PCB header
• 9 Volt battery clip (caution: typical wiring color coding on these is meant for the receiving side, so reversed for this supply-side application.)
• Dummy 9 V battery / clip holder (Printables # 260207)
• Soldering supplies, multimeter, wire, shrink tubing, etc.

Build instructions

1. Print both the soldering jig and enclosure
2. Pry open the USB sound card enclosure
3. Desolder the USB A connector from the sound card PCB 
4. Set the DC Boost Converter to output 9 Volts
5. Clip the PCBs onto the jig
6. Lightly screw in the panel mount connectors
7. Solder and crimp the wiring (see below)
8. Check for shorts - especially on the sound card given its tiny USB pads and close-by grounds
9. Confirm that your setup works using a computer
   • Check your audio device settings for things like automatic gain control or mic boost, disable for testing
   • Adjust the amplifier potentiometer
10. Unscrew the panel mount connectors
11. Unclip the PCBs
12. Install the threaded inserts onto the enclosure
13. Screw in the panel mount connectors
14. Install the PCBs and connectors in the enclosure
15. Screw on the lid
16. File a notch in the headset battery compartment door
17. Install the dummy battery
18. Clip the 9V ANR power wire onto the headset cable and connect to the adapter

Wiring

• USB
  • Vcc (red) to the boost converter input and sound card
  • D- (white) to sound card
  • D+ (green) to sound card
  • Ground (black) to boost converter input and sound card
• 9 V Booster to
  • Amplifier VCC
  • JST XH
• Microphone Jack
  • Ring to Amplifier Mic + (red)
  • Sleeve to Amplifier Mic - (black)
• Amplifier Mic out
  • Amplifier Out + to Sound Card Mic Tip (red)
  • Amplifier Out - to Sound Card Mic Sleeve (black)
• Headphone Jack to Sound Card Headphone Jack
  • Tip to Tip (blue)
  • Ring to Ring (red)
  • Sleeve to Sleeve (green)
• 9 V JST to Battery Clip Holder
  • Check polarity!
  • Optional: there is room for a cable to cable crimp connector inside the dummy battery, I used a JST SM but several types would be suitable, otherwise solder the battery clip's wire to a length of wire