Introduction: Rainbow Stick and a Crystal Ball

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

Step 2: Crystal Ball

We found an interesting geode in a rock shop. Typically geodes are hollow rock spheres that are opaque on the outside and quartz crystal on the inside. This geode had lost it's outer shell and remained intact except for a small hole about the size of an LED. I stuck one of my light pens in there and the sucker lit up like the Moon Rising in A.I.

So, I put 3 batteries together, wired 1 red and 1 blue LED in parallel (hoping to get purple), stuck them in the geode and set the whole thing in a bamboo cup made to hold an artist's paint brushes. For the time being, I twist the wires together to activate/deactivate the light, but a small switch drilled through the side or bottom of the cup will complete the lamp.

I think it looks quite nice.

Comments

author

These are both really cool projects!

author
GorillazMiko (author)2008-06-21

Awesome.

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!

+5/5 stars.
(added to favorites)

author

find a cheap place for leds?

author
funnylily23 (author)IkilledKenny2012-08-08

i know right

author
funnylily23 (author)2012-08-08

I love the crystal ball but how do you find the ball

author
unklstuart (author)funnylily232012-08-08

Thanks. That is a geode they I bought at a rock shop.

author
funnylily23 (author)unklstuart2012-08-08

thanks

author
kcls (author)2010-04-03

I love the rainbow stick... nice job!

author
bybabylove (author)2009-02-26

this is a very good idea 4 my science project and its goo it got me a A+ on my report card

author
Carlos Marmo (author)2008-10-30

Wonderful Work! Congratulations!

author
tudgeanator (author)2008-08-28

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!

author
sponges (author)2008-06-20

Awesome. The crystal ball looks like a prop from Star Trek TOS XD
"It's a being of pure energy!"

author
Plasmana (author)2008-06-20

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...
https://www.instructables.com/id/Spinning-rainbow-light-wheel/

4 star rating.

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