Avid trekkies may recognize the configuration from TNG episodes where flashlight type devices referred to as "palm beacons" were used. I've included a couple of screen shots from a scene in TNG episode "Disaster" where Riker is using one. I found the design to appear functionally efficient and to have versatility potential thus I decided to mimic it.
Mission Objective
To create a multipurpose LED lighting device that is compact, lightweight, portable, has a construction topology that makes it comfortable for hand-held use and multi-stable for hands-free use, and has high intensity light output. Accomplish this by using a combination of repurposed materials, and readily available low-cost materials.
Features
- Dimmable oscillator driver circuit for the LED array.
- Optional circuit to trickle-charge the battery from a conventional wired phone line. (yes they still exsist)
Required skills checklist:
Recommended skills checklist:
| Materials List: Housing Construction: | Required Tools: |
Make it so Mr. LaForge!
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Signing UpStep 1: Make the Reflector
Both the reflector and the radiused back cover are made from a single toilet paper tube split in half lengthwise. The tube needs to be undamaged, round, and have square ends. Use this technique to ensure that you end up with two equal halves, and that the cut edges are parallel.
1. Use a square head protractor set at 90*, or a combination square to draw a line the length of the tube square to one end of the tube at any point around the circumference of the tube.
2. On a peice of paper measure from one edge half the diameter (radius) of the tube and draw a line parellel to the edge.
3. Stand the tube on one end and align the line you drew on the tube with the line you drew on the paper, then keeping the marks aligned rotate the tube until the outside diameter of it is flush with the edge of the paper. Now while holding the tube in place make a mark where the other side of the tube intersects with the line on the paper, this will ensure that the second line is 180* from the first.
4. Use your protractor or square to draw a line the length of the tube square to the end of the tube at the 180* mark.
5. With a sharp pair of scissors carefully cut along both lines to split the tube into equal halves.
6. Choose one half to use as the reflector and set the other aside for later use as the back cover.
Reflections of... a String of LED's
1. Cut a piece of aluminum tape the length of the reflector.
2. Before removing the release paper from the tape curl the piece to match the reflector, place the piece in the reflector and center it side-to-side. There should be exposed cardboard on both sides as the width of the tape isn't enough to cover all of the concave surface area. Once the tape is positioned with equal cardboard exposure on both sides make reference marks on the cardboard along the edges of the tape.
3. Remove the release paper from the piece of tape, carefully align it with the reference marks and stick it down trying to avoid wrinkles, then smooth it out (see Figure 4) .
4. Again using the paper used to locate the 180* mark on the tube, now use it to find and mark the center between the 180* edges on each end of the reflector.
5. Center a craft stick on these marks and mark the aluminum tape along the edges of the craft stick (see Figure 5).
6. Score the tape on these lines with your utility knife being careful not to cut the cardboard.
7. Remove the center strip of tape exposing bare cardboard to later align and glue the LED array (see Figure 6).
8. Using your utility knife make a square cut on one end of 2 craft sticks and then cut them the length of the reflector.
9. Glue the face of one craft stick aligned fush to the edge and ends of each side of the concave side (inside) of the reflector, then use clothespins or small spring clamps to hold the sticks in place for a few minutes until the glue dries (see Figure 7).
10. Stand one end of the reflector on the face of a craft stick and align it with the ends of the reflector edge sticks (see Figure 8), then holding it in place scribe lines where the edge sticks intersect the face of other stick (see Figure 9). Use your utility knife to make these miter cuts on the scribed lines (see Figure 10). Then repeat this process for the other end of the reflector.
11. Apply a bead of all purpose glue to the mitered ends of one of the pieces you just cut and glue it between the reflector edge sticks flush to the ends and edges. Use strips of scotch tape as clamps to hold the piece in place for a few minutes until the glue dries (see Figure 11). Repeat this process for the other end of the reflector.
12. Cut strips of aluminum tape and cover the inside face of the craft sticks that form the reflector frame.
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I've never seen that type of oscillator before and I'm having a hard time wrapping my mind around it. Is there a technical name for it that I could google to learn more?
The oscillator circuit is similar to what has become known as a "Joule Thief". It's just a simple circuit that meets the most basic requirements to oscillate, feedback & gain greater than 1. For this project the function of the oscillator is to boost the voltage above 15V which is necessary to light the 5 LED's in series. I added a potentiometer, and chose the resistance values so that with a fresh 9V battery @ the dimmest setting the total (measured) current draw is about 13mA, & @ the brightest setting it's about 70mA. An advantage of this configuration is that even as the batteries voltage degrades the circuit keeps boosting the voltage allowing more of the batteries potential to be used when compared to a straight DC circuit.