i have this project that needs to determine the color of a paper... what sensor could you suggest that i could use in this said project... the paper is not so thin and cnt be easily reflected by a light...
can i use LED's...? but how could i use this LED...
yes you can use Bright leds and phototransistor.
put them in a way that the light will bereflected back to the phototransistor. You have to put them in a box so that there will be no light except the reflected one.
the output of the phototransistor may be amplified (if needed) and then a comparator can be used whose one input is the sensor and the other a preset voltage.
Change the value of the voltage using a variable resistor to set it to the desired color value.
Note the voltage of the reflected light will depend on the color of the paper.
You could use LEDs of different color to shine in turn (not together) on the sample paper.
An ADC will convert the response of a light sensor, for each color, to values between 01 and 255.
The combination of those values will identify one paper "color".
As far as I know, the disadvantage is that every time you repeat this circuit (build a new one), you have to teach what are the different values for a certain "color".