Color sensor using phototransistor... Help required

[solz7]

Hi all,
am doin a small project color sensor using PIC 16F877a. I used LDR but its not sensing the different colors that are reflected from 3 leds RED BLUE GREEN. So I changed to phototransistor. Now i need a circuit for the same. Because all my works are in vain. I am givin the circuit that i used with LDR.

img220.imageshack.us/img220/7573/colorsensorusingldr.jpg

 

[sunny1986]

HI... U CAN USE A IC FOR COLOR SENSING i.e Agilent HDJD-S722-QR999 Color Sensor that sense color and give u a particular voltage than use adc to convert analog to digital and then connect to microcontroller

if ic is costly then use three led for three different color for example u want to detect red color simply use red led at place of ldr
as red led pass more current on red light fall on it........use same theory for all

 

[solz7]

tnx 4 ur interest sunny....
the thing is i hav to use a phototransistor and PIC for compulsory...
plz help on that...

 

[sunny1986]

......may be phototransistor gives output at all frequency rather than single one so it may not be use for color sensing.......

 

[solz7]

wot bout photodiode or LDR....????

 

[sunny1986]

THEY BOTH ARE ALSO SAME WORK AS PHOTRANSISTOR..............READ AN ARTICLE ON Color Sensor from a Reversed LED and Op Amp - Robot Room .......U CAN USE REVERSE LED FOR COLOR DETECTION

MOD: Dont use all capital letters unless necessary

 

[ammarabbasi]

This may help you !