The Coolest (and smallest) 9V LED Flashlight ever

In this tutorial describes the step by step process to build a very efficient, small, simple, long-lasting and cool LED flashlight. This is a very simple project, so I encourage anyone to attempt it. Here goes...

1. The Parts

What you will need:

1. Rugged plastic 9v battery clip (also called a PP3 clip)
   
2. Push button switch (aka a Tact switch)
3. Jumbo (10mm) LED or a really bright 5mm LED (choose super- or ultra bright)
   
4. The proper resistor(s) for your LED (I'll show the calculation)
   
5. 9 volt battery, of course
   
6. Some hot glue and a glue gun
   
7. Lastly, a soldering iron with some solder

The 9V battery clip, LED(s) and resistor(s) can all be purchased at almost any electronics store like RadioShack. My push button switch came out of an old (broken) VCR - check out some old junk and broken electronics. They usally have buttons that click, and you will probably find some satisfactory switches inside. You could always buy them new if you wanted to (see digikey.com). If you are going to get your switches out of something old, though, you will need to use a "desoldering iron" to remove it. A simple solder sucker works just as well.

Figure 1 : Before and after

2. What LED and resistor(s) to use

For my design, I used a large (10mm) red LED, because it would be very useful to use it on campouts (the red won't ruin your night vision). O and also, because I had it on hand. If you are making a light that you can actually hope to use, then I suggest using a stronger LED that has a higher lumen or millicandella rating (several thousand millicandella (mcd) would be better). These LEDs are not as bright as Power LEDs (see my other tutorial here), but they are cheaper too. I had some strong LEDs here that have 10,000 mcd! Now that's bright! Remember that you should use a resistor in series with a LED, to limit the current and thus protect the LED. But how can we calculate which one to use? You could do it yourself, but then I would have to explain the steps. Rather go to this site and have it done for you.

Figure 2 : Disassembled

3. Putting it all together

Now that you have all the parts you need, it's time to get building (aka the fun stuff).

The easiest, and probably quickest, way to go about this, would be to use the glue to fix the switch, LED, and resistor in place before doing any soldering. If you did this, you can cut the PP3 clip wires to just the right length. Your friends will be impressed with your soldering work. Now, do the next steps WITHOUT the battery clip on to the battery terminals.

Use a wire stripper (I used my teeth) to strip a little bit of plastic off of the ends of the wires, after you have cut them to the perfect length. Next, dip them in flux and tin the wires with some solder. This will make it easier to attach when you're making the connections. The flux will make the solder spread nicely and evenly all over the wire.

Look at the LED. It will have two leads coming out of it. One will be shorter than the other. That one is the negative terminal, the other one is positive. Sometimes the plastic of the LED will be flat on one side. This is the negative side.

The rest is rather logical. Connect the red wire to the positive lead of the LED. Connect the black wire to one of the four legs coming out of the switch. Solder the resistor to the leg that is diagonally across the switch (from where you connected the black wire). Then connect the remaining end of the resistor to your LED. Check to make sure you connected everything correctly. And then cut off the extra two legs on the button switch that you didn't use.

Put on some more glue to make sure everything is on properly. I added some red tape around the battery for the looks.

Thats it! Finished! And you have just made yourself one heck of a great beginners LED flashlight!

Figure 3 : It's alive!!!