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IR LED
The main difference between LED and IR LED
is that IR LED emits Infrared Radiations, which we
cannot see by our visible eye. The second
difference is that IR LED takes a lot of current and damage
fastly than LED's. I will explain more about 38KHz IR transmission
and reception in Sensor's section. But we can use
IRLED with photo diode as a sensor, which makes
less prone to external light effects compared to
LDR+LED combination. As you know IR radiations are heat emitting
radiations,so be careful when you touch the IRLED's light emitting
portion. I got 5-7cm clearance when i used
IRLED+photo diode combination for edge
detection.That is if I height is greater than 7 cm no reflection will
come from ground, if it is less than 7cm then reflection will come
from ground and photo diode detects it.
NOTE: IR LED become heated fast. Remember that IR LED always
creates too much problems, most of the time it won't lit,that means
the voltage across IR LED should be>2V for it to
lit('lit' means produce IR radiations).
ANALYSIS: Here I connected the output of 7805 directly to
LED then voltage output of 7805 become 3.85V for
LED and 1.5V for IR LED(previously without
connecting any load it was 5.02V). If i connect a
330 ohm resistor series with IRLED and LED then voltage output
becomes 4.95V
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