2015-10-05 (M) Wrist Mounted Chording Keyboard


TSAL6100 diodes were stocked and offered some light filtering by their tinted housing. These diodes were stocked while working on laser tag guns. They provide excellent long-range transmission which may be overkill for this project. Two diodes were installed into the transmitting and receiving tubes using a pair of 5mm LED mounts. Wires were not neatly arranged or soldered.

New diodes ready for testing

Diodes installed in emitter and receiver tubes

Testing was to test the limits and capabilities of the diodes. Normally these would be referred to as infrared light emitting diodes, or IR LEDs, but since one is used as a receiver, a photodiode, it made sense to use the more generic of just diode.


Testing showed that the emitter and receiver pair did work but far from perfectly.
  • Good on white paper
  • Great on mirror
  • Good on reflective tape
  • Medium on bare skin
  • Poor noise interference from ambient sources
Most promising from these results was the testing with reflective tape. Reflective tape was from a back pack which was added to increase night visibility. It is pliable, durable and suitable for clothing. A ring made from this reflective tape may be a good way to interact with the detector. 

The test was done by strobing the emitter diode slowly, 1.5x/sec, and using an analog input to read the receiver. A red LED was connected in parallel to the emitter and can be seen strobing in the video. A green LED was connected to an output which went high when the analog input went to full voltage. When the green LED flashed synchronously with the red LED a good connection was being made.

Materials arranged for test

Video demonstrating some of the tests

Downloadable Files:
To do:
  • Wrist mount
    • Terminal board
      • Input voltage
        • USB
    • Make base for keyboard
      • Spacers 
      • Magnet mounts
    • Integrate:
      • Enclosure for each controller
        • Potentiometer access
      • Activation switch
    • Debug 
    • Test
    • Refine
    • Repeat
  • Write instructions
    • Compress and link to all files
      • OpenSCAD files
      • STL models
      • Arduino code 
    • Make diagram with every part labeled 
    • Schematic for servo controller

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.
Completed projects from year 2. 

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2015-10-05 (M)

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