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thank you friend.... the color of line is black/white only... LM324 works properly but when connected with ldr and led,,,, the Ldr is not detecting the light from Led though it is placed nearer(2cm) .... ok i wish to try with IR sensors... thank u
I found that the problem is on LDR only.... it is not capable to absorb light from normal LED... what can I do now...? Is it advisiable to try with other color LEDs??? Will LDR responds to IR led..????.
I would use a CdS cell (also known as a photocell). A circuit like this can be very simple, and I've heard it has been done before. Any color that is dark, such as a black line, will increase the resistance of the CdS cell. Anycolor that is light will decrease the resistance. You should be able to find a circuit that wil let you adjust the sensitivity of your CdS cell for a certain color. Search for something like this.