Light-emitting diode

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(LEDs used "in reverse": as light sensors (moved from sensors))
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Light emitting diode
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A '''light emitting diode''' is the most popular kind of [[optoelectronics]].
  
 
To make the LED light up, you need a power supply (any voltage) and a resistor.
 
To make the LED light up, you need a power supply (any voltage) and a resistor.
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You then connect a 190 ohm resistance in series with the LED to make it work.
 
You then connect a 190 ohm resistance in series with the LED to make it work.
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== POV ==
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[[POV display]]
  
 
== sensor ==
 
== sensor ==

Revision as of 19:25, 26 July 2008

A light emitting diode is the most popular kind of optoelectronics.

To make the LED light up, you need a power supply (any voltage) and a resistor.

The resistance required is as follows: R = (U_power - U_led) / I_max

Example: a LED with voltage drop of Uled=1.2V and a max current of I_max=0,020A (20mA) to be powered by a 5V DC source needs:

R = (5-1.2)/.02 = 190 ohm

You then connect a 190 ohm resistance in series with the LED to make it work.

POV

POV display

sensor

A few people use LEDs in an unusual way: as sensors.


further reading

LEDs used normally: to emit light:

http://en.wikipedia.org/wiki/LED

LEDs used "in reverse": as light sensors:

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