Here's my first instructable for a LED safety light. I decided to make it after wanting to make some lights for my bike and after seeing some guides on LED wiring. First I was going to make a 4 LED light but ended up making it 8 for better illumination. Constructive criticism is welcomed.
Step 1: I. Materials.
1. Hot Glue Gun, or Soldering Iron
2. A Needle/ Safety Pin ( to heat up to make a small hole)
1. Mini m&m Container
2. 8 LEDS (color is your choice) 3.2v @ 25 ohms (estimate) bought as a multi-pack at RS
3. 4 100 ohm resistors
4. A piece of 3 inch wire
5. Toggle Switch (or equivalent)
6. 1 9v battery
7. 1 9v snap connector
Step 2: Ii. Wiring the LED's
I made the holes on the lid of the m&m container with a heated up safety pin. Then followed this guide from a LED calculator website. You should do two at a time and go from there adding as many LED's you want, as long as they're a pair you only need to add an additional 100 ohm resistor. I used hot glue to insulate the wires under the cap, becareful to make sure it'll still close.
Step 3: Iii. Installing Battery and Switch
You can see a picture of the 4 resistors I used to in making this light.
You stick the battery with the snap connector into the tube (it's a tight fit but it'll work) with the wires sticking out. Make a hole (note) and stick the positive wire through it. Connect it to the "off" part of the switch. Then connect the peice of single wire from the bundled resistors (note 2) to the "on" part of the switch (out the hole).
Step 4: Iv. Finishing.
Here is the final product. The little light is pretty bright, a perfect light for a back bike light.
Yeah the big toggle switch looks funny, it's the only one I had. Let me know if you had any questions. I hope you liked this instructable.