The small lights can easily be placed on your jacket or hat. They will help people see you when you cycle while it is dark outside.
Step 1: The parts
1, A small metal binder clip
2. masking tape (other types of tape would work but I find masking tape easy to use)
Less common items:
1. LEDs (the yellow and red were my choice) A package of 20 assorted LEDs at Radioshack goes for about $3.00. But if you are serious about lowering your cost buy the LEDs online. There are many online suppliers. The Electronic Goldmine site (interesting site I plan to use soon) had various packages of LEDs. You want T1 type and I think 5mm size is good. I believe the red, amber and green are the cheapest.
2. Small batteries. These battery are used for travel clocks and lately they show up in those musical greeting cards. I bought an off-brand pack of 24 for about $3.00.
So depend on the quantities purchased you should be able to make the lights for less than a $1 each.
Note the positive lead of the LED is slightly longer than the negative lead. The positive and negative leads must be connected correctly for the LED to light.
Step 2: Assemble the parts
Each battery is 1.5 volts so two batteries are needed to light the LED.
The positive side (+) is typically labeled. See the picture below to help you identify the polarity of the battery ends. Note the positive lead will have the positive side of the battery touching it and the negative lead will have the negative side of the battery touching it.
Step 3: Complete the circuit
The finished light can be thought of as a sandwich. Starting on the outside is the binder clip, then a layer of masking tape, followed by LED leads, then batteries, and finally the other side of the binder clip.
The arrangement allows you to stick the light on your clothes.
I noticed that clip sometimes did not land on the parts correctly and the circuit failed to complete. Moving the clip around a bit helps locate it in the right spot.
The next step shows and optional way to finish the light.
Step 4: Optional arrangement
With this option the layers are:
outside of clip
one LED lead
second LED lead
other side of clip
Note the batteries need to placed so a positive side presses against the other's negative side.