LED
From uCtrl.net
Lights emitting diode.
Contents |
Information
A LED is a diode that emits lights, this happens when electrons jump from one shell to another emitting a small burst of light. The operating time is around 100 000 hours, at which point the luminous intensity has been reduced by 50%. LEDs are very power efficient, and are starting to make their way into lighting appliances.
Calculating resistor value
- Vf = LED voltage (1,2-4 V)
- V = Supply voltage
- If = Current through the LED. (e.g. 20 mA)
- R = resistor value in ohms.
R = (V-Vf)/If
LED-display
LCD-display and AVR
Every segment is controlled by a output, and the cathode is common. To be able to show different numbers on two or more displays at once they have to oscillate. One number is displayed at any all times, but they change so rapidly that we see them as constant numbers. Typically every 5 ms or faster. This is possible because each number has it's own common cathode.
Modules using LCD-displays: Light sensor.
Numbers and binary values
| Segment | Binary |
| 0 | 63 |
| 1 | 6 |
| 2 | 91 |
| 3 | 79 |
| 4 | 102 |
| 5 | 109 |
| 6 | 125 |
| 7 | 7 |
| 8 | 127 |
| 9 | 111 |
Images
 Two colored LED |
 Red LED lamp in bedroom |
LED display |
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