Difference between revisions of "Light-emitting diode"
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*[http://www.robotroom.com/ReversedLED.html Making an Amplified Color Sensor from an LED and an Op Amp] | *[http://www.robotroom.com/ReversedLED.html Making an Amplified Color Sensor from an LED and an Op Amp] | ||
* [http://www.redrok.com/electron.htm#led1 LED1 LED Sensor Relay Tracker Schematic] | * [http://www.redrok.com/electron.htm#led1 LED1 LED Sensor Relay Tracker Schematic] | ||
| + | * [http://electronics.stackexchange.com/questions/19051/what-are-the-relevant-parameters-for-a-reverse-biased-led-light-sensor "What are the relevant parameters for a reverse-biased LED light sensor?"] | ||
Revision as of 21:42, 4 October 2011
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.
Contents
POV
throwies
Several other wiki discuss how to turn LEDs into "throwies":
- Cybords wiki: Throwie Talkie: A Talkie is a Throwie that has been hacked to blink graffiti messages in Morse code.
- TagRecord.com Wiki: Led throwies
- the mayowiki: Throwies
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:
