Hi all, i need to sense the colour of 3 leds: red, green and yellow, lighting up once at a time. I've thougt to use an Osram light sensor like SFH5711, and to value the output current, to distinguish which led was lighted up. Do you have any other ideas ?
thanks in advance
mauri
Sure, use some red green and yellow leds to sense the light. LED's will output somewhere around the same voltage they take to excite when exposed to light at the same wavelength.
Some stuff already exists on the web on using leds to sense light and color.
It is very low current - but something you can easily measure with a
10 megohm voltmeter in sunlight. LED's, or at least the common 5mm diameter size have a relatively narrow angle of acceptance from 5-20 degrees depending on the lens.White leds are most sensitive to blue violet light, but do catch other colors.
Use colored LEDs as the sensors?
John
You could use a TAOS TSC230.
snipped-for-privacy@yahoo.it hath wroth:
You can use multiple LED's or color filters to sense color. That's the way some older hardware store paint color matching systems work. However, methinks it would be easier to use a cheapo CCD or CMOS color camera and determine the color from the resultant digital or NTSC data.
Perhaps forget the colour.. Just go for "light or no light"... Cap the LED's with phototransistors. Maybe use tiny SMD phototransistors so as not to obscure the LED's too much.. Or...resort to current or voltage sensing per LED.
D from BC
On a sunny day (Mon, 08 Oct 2007 13:34:08 -0700) it happened snipped-for-privacy@yahoo.it wrote in :
Color webcam? grin:-)
I have used the TAOS TSC230, as previous poster mentioned, it works very well.
Lyn
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