Pre-Confirmation to our Project (Color Sensor)

COLOR SENSOR

·         The circuit can sense eight colours, i.e. blue, green and red (primary colours); magenta, yellow and cyan (secondary colours); and black and white

·  colour is required to be detected should be placed in front of the system

·    The light rays reflected from the object will fall on the three convex lenses which are fixed in front 

of the three LDRs.

·         convex lenses are used to converge light rays and helps to increase the sensitivity of LDRs.

·   When reflected light rays from the object fall on the gadget, the coloured filter glass plates determine which of the LDRs would get triggered

·    The circuit makes use of only ‘AND’ gates and ‘NOT’ gates.

·  When a primary coloured light ray falls on the system, the glass plate corresponding to that primary colour will allow that specific light to pass through. But the other two glass plates will not allow any light to pass through

·        Thus only one LDR will get triggered and the gate output corresponding to that LDR will become

logic1 to indicate which colour it is.

·      Similarly, when a secondary coloured light ray falls on the system, the two primary

 glass plates corres- ponding to the mixed colour will allow that light to pass through while the 

remaining one will not allow any light ray to pass through it.

·         As a result two of the LDRs get triggered and the gate output corresponding to

 these will become logic 1 and indicate which colour it is.

·         When all the LDRs get triggered or remain untriggered, you will observe white and black light indications respectively. Following points may be carefully noted :

1. Potmeters VR1, VR2 and VR3 may be used to adjust the sensitivity of the LDRs.

2. Common ends of the LDRs should be connected to positive supply.

3. Use good quality light filters.