COLOR DETECTOR

[shriek]

Anyone here know a COLOR DETECTOR CIRCUIT?
the project i'm working on is a snooker scoring system, it's not a typical snooker game.. it only has 2 sets of colored balls and 1 for the cue ball, it really doesn't matter what color but i'm thinking the first set will be black and the other-red then white for the cue...
The color sensor/detector will be placed inside the corner holes(it will be dark) It will detect which color fell on it, then a program will monitor the whole game and do the scoring, so the circuit will also be interfaced to a computer and a display to show the scores... any ideas?(pleeease )

 

[Lou1]

Hi

I think you'll need three detectors: one barrier type, detecting any ball including the black one and two reflective type. One will have a red LED as a source and will react to white and red balls, the other will have a green LED as a source and will only react to the white ball. By combining the informations from the three sensors, the program will be able to determine the color of the ball.
Lou

 

[Alun]

That would work, but you only really need 1 detector.

When the the ball falls on a switch the circuit could be activated.

First you turn on a red LED and then a green LED, measure the reflected light on each occasion.

The black won't reflect much of either colour.

The white will reflect both.

The red will only reflect red.

Two high brightness LEDs could be used for the light source and a general purpose photo-transistor detector will do as a detector. Don't use the black photo transistors as their only sensitive to infra-red light. Most photo-transistors respond better to longer wavelengths (is will be more sensitive to red than green) so you will have to make the red LED a bit dimmer than the green you could just use a larger value series resistor.

Alternatively you could have two sensors, one with red and the other with green coloured filter, and operate the red and green LEDs simultaneously.

You could also try using high brightness LEDs as sensors, an LED will generate a small voltage when illuminated by the same coloured light that it emits, so use a red LED to detect red and a green one for green.

 

[AJB2K3]

A simple to build one was made or lego mindstorms. goggle for lego color sensor
it uses 4 led (transmitters) and one reciver.
the leds are Red Green Blue and are mounted around the detector.
each led is pulsed in sequence and the programming works out which is the corect color for the value.
http://www.philohome.com/sensors/colorsensor.htm

 

[MP1]

Here is also a link that might help you in measuring light with regard to color frequency.

http://www.sensorsmag.com/articles/0500/26/main.shtml

MP

 

[Kevin Weddle]

How I think it works. Use three color sensistve light receivers. The intensity modulates with the three oscillators connected to the three light receivers. You can combine the three signals on one line. Then the waveform produced carries all three basic colors and their intensity.

 

[AJB2K3]

How I think it works. Use three color sensistve light receivers. The intensity modulates with the three oscillators connected to the three light receivers. You can combine the three signals on one line. Then the waveform produced carries all three basic colors and their intensity.

i think the link i posted is simpler
because the CPU will have 3 variable.
the sensor has a red/blue/green led
and a red/blue/green variable
but one reciver.
when the blue led is lit, the ldr's reeding is added to Var blue,
when the Green led is lit, the ldr's reeding is added to Var green,
when the Red led is lit, the ldr's reeding is added to Var Red.
the the cpu just checks a look up table, if the values fall into a certain table you got you color.