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I m using IR sensor ir tx and photodiode for rx for my line follower bot it's working in normal light and night time but when put in sun light it's not working all sensor showing high ouyput. Also I find out that sun light have high wavelength so that photo diode shows always high signal. Is that any other way to work line follower in day light time?

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You guessed it, sunlight has a lot of IR which is blinding your sensor. There are two common solutions for this problem:

  1. Put a small cap on the sensor to provide a shadow.

  2. Modulate your IR signal so that your sensor can detect an IR variation rather than fixed IR level.

For #2, you may want to look for components of IR remotes. There are IR receivers which have signal demodulation built in and there is plenty of IR transmitter circuits which modulate the signal for you. Common modulation frequencies are 38 and 48 kHz.

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  • \$\begingroup\$ I went for #2 it working but i got another problem in it for my line follower bot i m using two sensor left side & right side.one's IR rays interfere with other sensor signal suppose if left side IR led transmit right side (IR RX)get activated vice versa in certain cases. \$\endgroup\$ – sarfaraaz Apr 14 '16 at 20:24
  • \$\begingroup\$ So that i reduced tx range of ir led by adding 1k resistor instead of 470E at tx ir led side but in some rare case it behave same.Is there any other way to solve this or should i change ir led with minimum tx angle \$\endgroup\$ – sarfaraaz Apr 14 '16 at 20:33

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