Hello.
I'm in need for an advice for a project, that i'm not quite sure on how to start with...
I have just seen a cupboard in a shop today, with shelves made of clear plastic. The clear plastic shelves had LED's drilled in the back, so that there was a bluish form of light from them (really cool looking - and it was an QUITE expensive cupboard 
)
Now i want to make one - but only with my own kind of feature incorporated, and that involves an Arduino of course... 
I would like to make a similar cupboard (i have one already, just like in the shop - but without the LED's), and i want the shelves to change color, according to the average color of the room. Sometimes it's greenish, because of the sun shines of the trees outside, and sometimes its kind of red, because of the sun shining on the house next door. So that would involve some kind of color detection, i guess!!
BUT... the kind of color detectors i have seen, needs to have a internal LED glowing, and it only detects color 1-2 mm away from the sensor. So what kind of sensor do i need, to make a reading of the average color in the room (according to the placement of the sensor, of course). Do i really need a camera of some sort, because then its probably too complex to handle.
Any advise??? :~
Colour wheel on a servo and a phototransistor?
Besides emitting light Leds can also be used as light detectors. As such a led is most sensitive to the colour of light it emits.
Using 3 leds (or one RGB), you might be able to create a basic color sensor.
As such a led is most sensitive to the colour of light it emits.
No ... solid state physics shows that a photon of a higher energy that the energy gap in the semiconductor will always register so an LED is like a low pass filter. In other words a red LED is always going to detect blue light.
Anyway the project idea is flawed. The eye perceives the illuminating colour as being white and adjusts all the other colours accordingly. Therefore the shelf will always look the same colour and that will always be seen as white.
Hi,
Look at the TAOS color sensors. Way cool.. http://www.taosinc.com/Productfamily.aspx?id=5&SD=cs
---------------------( COPY )--------------------------
The TCS3200 and TCS3210 programmable color light-to-frequency converters that combine configurable silicon photodiodes and a current-to-frequency converter on a single monolithic CMOS integrated circuit.
The output is a square wave (50% duty cycle) with frequency directly proportional to light intensity (irradiance). The full-scale output frequency can be scaled by one of three preset values via two control input pins.
Digital inputs and digital output allow direct interface to a microcontroller or other logic circuitry.
In the TCS3200, the light-to-frequency converter reads an 8 x 8 array of photodiodes. Sixteen photodiodes have
blue filters, 16 photodiodes have green filters, 16 photodiodes have red filters, and 16 photodiodes are clear
with no filters.
-----------------( END COPY )----------------------
I am supposed to get some of these from a source in China (The earlier TCS230D which is a 4x4 array) which I could sell for, um, $5 I guess.
Not enough time to play with these toys!!
I finally got some of those TCS3200 color sensors for a good price:
http://arduino-direct.com/sunshop/index.php?l=product_detail&p=179
DISCLAIMER: These are in my own shop...