Blending colored light beams is absolutely amazing and fascinating!  By hacking three (extremely cheap) Ikea spotlights into red, green and blue light sources, you can make a fascinating science experiment set-up or museum exhibit.

There are two things about this experiment / activity that I really like:
- It's attractive and educational for all audiences: for toddlers and grandparents, college students and high school kids.
- The lamps give a great opportunity for kids to explore and wonder, without the direct need to "produce the right answer".  

In the video, three 10 year old Dutch girls explore the lamps and the way the colors mix. They unravel the mystery of the yellow shadow by themselves, by covering the lamps one by one. I only interfere by asking questions about what they observe. The conversation in the video between the kids and me is in dutch. I'll add english subtitles later on...

Video doesn't play? Watch it here.

The Magicolor Shadow Lamp is not targeted to a specific audience. It can be used in a lot of different, formal and informal settings.

I suggest to offer the Magicolor Shadow Lamp to pupils in groups of two or three. That way they can help each other handling the lamps and discussing and analyzing their observations. Which is, as far as I'm concerned, the most important learning objective of this device.  

Educational goals / learning objectives
The Magicolor Shadow lamp can be used to accomplish numerous educational goals. Besides the "obvious" learning objectives in the scientific subjects (see below), a number of more general skills can be reached:
  • Pupils get the opportunity to explore a phenomena connected to light and/or color, initially in a way of their own (when using the lamps during a class, focus on one phenomena at a time).
  • Pupils learn to closely observe an "scientific" event.
  • Pupils analyse the properties of colored and white light by manipulating different light sources and combining them. Analysis is facilitated by letting the pupils work in small groups (3 pupils). 
  • Pupils structure and reflect on their findings by verbalizing their thoughts to each other and preferably also to a teacher.
  • By letting the pupils have a presentation of their findings, in which they use the lamps again, they learn to structure information, cooperate in a group and present themselves to an audience. The lamp now functions as a tool to demonstrate a phenomenon.

The lamp can be used to explore a number of scientific phenomena :
  • How white light is made up of primary colors red, green and blue
  • How red, green or blue light can blend into other colors (yellow, cyan, etc.)
  • How blending colors of light differs from blending colors of paint (additive blending vs subtractive blending) 
  • How shadows appear, and how the shape and brightness of a shadow changes when the light source is moved to and from an object.
  • [add your own here]

Hacking the Ikea lamps into red, green and blue spotlights takes about one afternoon, and will cost you around €35 / US$50. It's a bargain, really, for a setup that causes so much fun, wonder and amazement.

Step 1: Tools and Materials

The stuff you need for making three rgb-spotlights is pretty straightforward. I used:

  • Three Ikea Jansjö spotlights (Ikea US, Ikea NL). I bought them for €5 each as a discount item. Regular price in NL is €10,-
  • Leds: red, green and blue. I used 5mm superflux leds because I already had them. Beside the leds, you also need the specifications of the leds, which are easy to find on the internet. More generally speaking: You need superbright leds with a flux of around 4 lumen for red and green, and 2 lumen for the blue led. Red and green leds are around €0,50 / US$ 0,70. Blue leds cost around €1,50 / US$ 2,-
  • Resistors to adjust the current through the leds. I used 22 Ohm for the red LED, and 10 Ohms for the green and blue LEDs. More on calculating the resistor-value in step 3.
  • A plastic sheet, 2mm or so thick
Total costs shouldn't exceed €35 / US$50
Leds and resistors can be bought at Conrad, Farnell or RadioShack

If you want to be able to dim the lamps (step 8 and further), for each lamp is needed:
- 2x capacitors 10 nF
- 1x transistor BC547(B)
- 1x transistor BC557(B)
- Resistor 5k6 (or 4k6, if you want to dim the leds to zero)
- Resistor 10k
- Resistor 330k
- Potentiometer 50k

- Jumper wire
- Nuts, bolts and spacers to mount the pcb in the casing.

I haven't finished building the dimmers yet. The prototype circuit in step 8 does work, however.

  • Soldering iron and solder
  • Fretsaw
  • File: a small one with sharp corners (I used a file with a triangular cross section)
  • Drill and drillbits: 1.5mm and 12mm
  • Screwdriver (philips screw)
  • Straight screwdriver or blunt knife to lift the lens cap from the spotlights.

<p>Can you add specific links for the LEDs and other items that you got?</p>
<p>I used these LED's: <a href="http://www.farnell.com/datasheets/1677197.pdf" rel="nofollow">http://www.farnell.com/datasheets/1677197.pdf</a></p><p>The other components are commonly available. If you starting with electronics, you might want to get assortment kits with resistors and capacitors like these:</p><p><a href="http://www.vellemanusa.com/products/view/?id=500317" rel="nofollow">http://www.vellemanusa.com/products/view/?id=50031...</a> (resistors) and</p><p>http://www.vellemanusa.com/products/view/?id=521756 (capacitors).</p>
<p>Alright! Thanks for the links! </p>
This is really awesome!
This is really awesome!
I love that dimming circuit.
Me too, and it works great! Extra fun: when you attach a loudspeaker instead of a LED, it becomes a totally funny mini-organ (the frequency range of of the pulses is about 300 - 4000 Hz: audible! :-))
Fascinating! <br>It is so coool,dude!~
Thanks :-)

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