In this Instructable, I will be showing you how to make an adjustable speed pocket fan out of some cheap and easy to find materials. I know that this has been done before, but it doesn't look like anyone has done it this simply. Many designs use a 555 timer to control the speed, but this one simply uses a variable voltage regulator for speed control. Also, this one costs less than 10 dollars depending on the materials you are able to recycle.
This fan is very small, and actually has a pretty good output as well. It will run for several hours on it's battery.
Step 1: Tools and Materials
There are a few simple materials you will need to make this fan (all links open in new tab).
1) A 12v computer fan of any shape and size, I used a small DC Fine Ace fan but really any computer fan will work, this is just what I happened to have on hand.
2) A small 12v battery, I used this one. I like this one because it is tiny and has a pretty good output and capacity. It is also really cheap, which means you can buy a bunch of them and swap them out. All around, they are great.
3) A 2k potentiometer. You might have one of these on hand, but if not, they are easy to find and very cheap.
4) A small switch. You probably have one of these on hand, but otherwise, go ahead and pick one up.
5) An LM317 Adjustable Voltage Regulator. You probably don't have one of these on hand, but they are pretty cheap from SparkFun.
6) Some wire, preferably solid core.
7) A plug for the battery. I ripped one out of an old broken RC helicopter, but if you don't have one, you can simply use some header pins.
8) A 330 ohm and a 1k ohm resistor. If you don't have any on hand, I recommend this.
9) An LED. I used a red one that I had on hand because it gave off a soft warm glow.
The only tools you will need are a soldering iron, a hot glue gun, and a wire stripper.
Step 2: Circuit Assembly
Use the pictures to guide you through the process. Note that I am hot glueing all of the components down to the fan as I go. Don't worry about wiring yet, we will do that in the next step.
Step 3: Circuit Wiring
Step 4: Solder and Hot Glue
Make sure all of your connections are well soldered before hot gluing.
Step 5: Done!
That's it, you're done! Now, simply plug your battery into the connector. Flipping the switch will turn the fan on, and also light the red indicator LED showing that it is working. Use the potentiometer to adjust the speed of the fan.
If you have any questions, feel free to send me an email. My address is firstname.lastname@example.org
If you would like to see more of my projects, check out www.haxtothemax.com.