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Okay... There are plenty of Instructables here that explain how to build LED circuits, so we will not be reviewing that except to provide a few links.

My 'ible on Light Pens covers it as well as this tutorial on my web site.

Also see LEDs-for-Beginners. And search for LED to find many others.

Here are 2 recent creations.

The first is a light stick I built for the Maker Faire. It is a great light drawing device that will make a big picture quickly. See our Best of Maker Faire Light Doodles here.

The second uses a geode we found in a rock shop which makes an unusual home display.

Step 1: Rainbow Stick

This device is an extension of our light drawing pens. I strapped 6 different colored LEDs to a 2 foot long stick with 3 AAA batteries and a switch postioned to easily turn off and on with your thumb.

The 3 AAA batteries are wired in series for a total of 4.5 volts.

The LEDs are wired in parallel to the power source and the switch is inline so they all light at once.

Since each LED has a different forward voltage and maximum current load, I wired a different size current limiting resistor to each. Here are the specs.

Power source is 4.5 volts

LED...................| Forward Voltage | Forward Current | Resistance

Super Blue.......| 4.0 volts................| 25ma..................| 20 ohms
Deep Red.........| 2.5 volts................| 25ma..................| 80 ohms
Yellow Green...| 2.5 volts................| 25ma..................| 80 ohms
Super Orange..| 2.5 volts................| 25ma..................| 80 ohms
Light Green......| 4.0 volts................| 30ma..................| 18 ohms
<p>These are both really cool projects! </p>
<em>Awesome</em>.<br/><br/>Your Instructables are always awesome, keep up the great work! I want to build one, and I have LED's -- a lot of them now. Thanks for the Instructable!<br/><br/>+5/5 stars.<br/>(added to favorites)<br/>
find a cheap place for leds?
i know right
I love the crystal ball but how do you find the ball <br>
Thanks. That is a geode they I bought at a rock shop.
thanks
I love the rainbow stick... nice job!<br />
this is a very good idea 4 my science project and its goo it got me a A+ on my report card
Wonderful Work! Congratulations!
Awesome. I have an idea! You could put loads of LED's really close to each other on the end of a big paintbrush and use that to 'fill' the pictures in!
Awesome. The crystal ball looks like a prop from Star Trek TOS XD<br/>&quot;It's a being of <em>pure energy</em>!&quot;<br/>
Wow! I love your rainbow stick, great work! I want to build one, but unfortunately I used all of my LED's to make this project, I will have to buy more LED...<br/><a href="http://www.instructables.com/id/Spinning-rainbow-light-wheel/">http://www.instructables.com/id/Spinning-rainbow-light-wheel/</a><br/><br/>4 star rating.<br/>

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More by unklstuart:Backyard Bird Photography Rainbow Stick and a Crystal Ball LED Light Drawing Pens: Tools for drawing light doodles 
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