A light-emitting diode (LED) is a specially manufactured diode that is designed in such a manner to glow, or emit light from it, when it is forward-biased. When it is reverse-biased, it will act just like any common diode; it will neither emit light nor it will allow considerable amount of current flow. LEDs can be designed to emit any color of the visible light spectrum we want, including “white” light. Red is found to be the most common color. For certain physical reasons, semiconductor material is especially efficient and sensitive to near-visible light in the infrared region. Consequently, many photoelectric eyes used for presence detection and industrial control functions operate in the infrared region.
Showing posts with label led diode. Show all posts
Showing posts with label led diode. Show all posts
LED Flasher Circuit Using 555 Timer IC
This is a simple LED flasher project that uses a common 555 timer IC for its operation. It is configured as an astable mode which means that its output is a square wave oscillator. Two LEDs are connected to its output in such a way that when one LED is ON, the other LED will turn OFF. It uses only 10 simple parts that are easily available at any electronic shops.
Capacitor C2 charges exponentially through resistors R1, R2 and the resistance of the trimpot. When C2 has charged to about 2/3 VCC it stops charging and it discharges to about 1/3 VCC through R2 and the trimpot resistance via pin 7. This is the standard operation of a 555 timer. When a Vcc of 5 V to 15 V DC is applied to the circuit, the LED will start to flash. The frequency of the flashing can be changed by varying the resistance of the potentiometer or trimpot.
Parts List
The parts list of the simple LED project is as shown below.
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