Monday, 30 September 2013

LED Light Pipe–Experimentation

During the weekend, I had an idea to make a fun toy for my daughter. The toy is basically a light pipe that transports light from a 20,000 mcd white LED through a bundle of clear nylon filament (fishing line) so that the tips of the filament fluoresce.

This is an incredibly simple project and one that only uses a handful of parts:

  • a 5mm 20,000 mcd white LED;
  • about a meter of fishing line (I used 20kg clear fishing line);
  • 5mm heat shrink tubing (mine was about 10cm in length);
  • some electrical tape; and
  • 6v battery

The legs of the LED are bent so that they can make contact with the battery terminals. The 5mm shrink tube is slipped over the LED and carefully heated so that only the part in contact with the LED is shrunk (the other end needs to be open so that you can feed the bundle of fishing line in).

Make a loop of fishing line so that the bundle is approximately 5mm in diameter. Stretch the loop out so that it is about 12cm long.

Cut the fishing line loop at both ends so that you end up with a bundle of cut lengths of line.

Feed the fishing line bundle into the open end of the heat shrink tube so that the tube is almost full (you may need more line for this).

light brush

Heat the heat shrink tube along it’s length so that it tightly grips the filaments.

Connect the LED to the battery and you have a light-brush. My daughter used the brush outside in the dark (and later in her bedroom) to make light patterns.

The LED is held onto the battery with some electrical tape and I made it so that the negative was not connecting unless it is held tight.

I’m going to make another one of these with a plastic tube to house the battery and with a simple touch terminal on the side so that the LED is lit when the tube is held.

Photographs of this will follow.

Sunday, 15 September 2013

Etcher – Instrument Panel design – Part 3

Today I attempted to put the etcher into practice and make the instrument panel for the device. I say “attempted” because, it didn’t work very well.


I transferred the image onto the brass plate, mixed a saline solution and gave it a whirl.


The negative charge was connected to the bath by way of another brass plate off-cut.

I painted the back of the work-piece with black enamel paint and connected a piece of wire to the work-piece with some electrical tape.


After some time in the bath (about 40 minutes) nothing much had happened. The transfer was able to be peeled off the work-piece, so I guess it didn’t adhere properly. Also, the enamel paint peeled off the back of the work-piece … so not much of a resist.

I next tried soldering the wire onto the work-piece and using duct-tape as a resist on the back of the work-piece.

To make sure that the work-piece was held off the bottom of the bath, I put in some marbles.


Again, the transfer peeled off, and  the tape started to come off the back of the work-piece.


Disappointing result.

There is a deposit on the negative plate, so obviously something was happening … maybe just not enough.

There are a couple of possibilities:

  1. My use of a 6.8 volt AC adapter may not be enough to make the reaction work properly;
  2. The paper that I am using to print the design on may not be suitable;
  3. I may not have cleaned the paper off the design enough (to leave only the laser toner on the plate);
  4. Something else that I haven’t worked out yet.

I have done this before with steel and a 12 Volt power supply (a car battery charger). So maybe I need to go back to steel and/or the 12 Volt power supply to see if I can get it working that way.

Oh well. I may not have got the results that I planned, but I am not giving up just yet.

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