- Controller can power up to 360 watts of LED lighting - between 3 and 100+ power LED's
- Analog dial or slider for Red, Green and Blue - create an infinite number of light colors!
- easy to make a room light or a spot light by switching lenses / covers
- very fine analog control for precise color matching (or white matching)
- Includes current-limiting protection circuit
- Simple 7-component thru-hole circuit - No microcontrollers or programming!
- Controller cost: $25
- 50-watt, 15-LED lamp cost: $50
- Efficient: 50 watts of LED light equals 100 to 150 watts of incandescent light.
- Efficient: 80-90% controller efficiency
- Controller can be used with a variety of power sources
- Recycled materials & electronics: 20-40%
I've included a lot of detail in this instructable that applies to any power-LED project, and i've got several other power-LED instructables too, check those out for other notes & ideas.
why not digital?? this controller was specially designed to be as simple as possible by using analog-only. it turns out that it works really well. yes, a digital PWM controller is "better", but it requires "chips" and is thus more complicated to build. i've included a circuit for a digital PWM controller here.
This article is brought to you by MonkeyLectric and the Monkey Light bike light.
Step 1: How does color mixing work?
lets start with your eye, which is an incredibly complex and sophisticated image sensor. how does your eye see an image? your eye has millions of individual sensor cells, a bit like the pixels in a digital camera sensor. your eye has 2 major types of cells: rods and cones. there are about 100 million rods, they are very sensitive to light but only see black and white images - they are your night vision. there are also about 5 million cones, which come in three types. each of the three types of cones sees different colors. you can think of the three types of cone sensors as 'red cones', 'green cones' and 'blue cones', although this is a bit of a simplification of how it really works.
so, how do we see colors? every color you can see is a result of how your brain interprets the signals it gets from the three types of cones. if you look at something and only your 'red cones' see it, then your brain sees red. if you look at something and both your 'red cones' and 'green cones' see it, then your brain interprets yellow. every color you can see is the result of how the brain interprets the different strength of signal from the three types of cones.
how does that help us? it means that using only three different colored lights (red, green and blue), we can easily fool the brain into thinking it is seeing any possible color. lets say we have a real yellow light: this light activates both the red and the green cone sensors in a specific proportion. but we can also activate the red sensor with a red light and the green sensor with a green light. if we activate the two sensors in the same proportion that the yellow light would have, then our brain can't tell the difference from a real yellow light and we see that red plus green equals yellow. we've fooled our brain!
it turns out that this is a very popular trick. every color television and computer screen ever made uses this exact principle! also most printers, cameras, and other imaging devices are based on this principle. if you have an older 'tube' screen or a plasma screen - look closely at it while it is displaying images and you can see all the small red, green and blue pixels (a magnifying glass helps).
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