2015-06-14 (Su) Vibrating Distance Sensor

A new flashlight was found which had desirable qualities for this project. The bezel was recessed so there was built-in protection for the ultrasonic sensor in case the project was set face down which is a natural thing to do with a flashlight. Instead of a two-pack these flashlights were available individually for less than the cost of the original lights. Additionally this model had room for two D-cells which isn't very important since not much internal space is used. Future models may use AA cells for extended life.

Measurements were taken to create an adapter for this light. This version was intended to be more complex and be able to use the flashlight's switch to cut power. Normally the switch operates by breaking the connection to the negative terminal of the power cells but this requires a conductive ring inside the flashlight which has been removed to make room for the distance sensor. Using the original switch was important since it integrated with the structure of the flashlight and replacing it would be troublesome although cheaper. A lever-arm microswitch will be built into the adapter design so the moving segment of the flashlight's switch will press the switch and supply power to the processor.

Outside diameter of flashlight

Inner diameter of flashlight

Sensor resting on lip of bezel

Thickness of PCB

Modeling was done to create an updated flashlight adapter. The diameter between the old adapter and new was smaller. Since the diameter was smaller there was not enough room for mounting screws to hold the ultrasonic sensor in place. This version will rely on a small amount of glue to hold the sensor in place but once the flashlight bezel is tightened it will be held firmly in place without glue. Glue is only there to keep it in place when the flashlight is open. Hot glue will likely be sufficient. Screw holes were removed by changing the code so adding ",true" when calling the distance sensor footprint will remove the holes. A post was added to the inside so a switch can be mounted which will be activated by the flashlight switch. It will likely be a lever arm microswitch.

Changes made to new flashlight adapter

A copy of the adapter was printed. The diameter was worrisome at first because it would not fit into the flashlight bezel easily. With some pressure however it fit securely and stayed in position by tension alone. The post for the switch mount could be positioned easily but the switches available were not well-suited to this application. Some switches were too large and some didn't feel reliable in this situation. Likely a magnet will be glued to the flashlight parts and a reed switch will be put inline with the power supply.

 Distance sensor positioned while resting on bezel

Distance sensor held in place

Files for Vibrating Distance Sensor:
The OpenSCAD files below are not necessary unless you want to change something

To Do:
  • Improve adapter for flaslight
    • Hold battery
    • Retract ultrasonic transducers
    • Thicker ring
  • Find and integrate switch
  • Write instructions

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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2015-06-01 (M)