IR Beam Alarm. Sensor Circuit.2


This is a highly sensitive broken beam alarm active both day and night. It uses invisible Infrared rays to inhibit the working of alarm generator. When the IR beam breaks, by a moving person, alarm will be activated. Ideal circuit as door protector.

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Invisible Burglar Alarm. Beginners Trial 2


You can easily make this Invisible Burglar alarm using Infrared LED and a Phototransistor. When there is no obstruction in the path of IR rays, alarm will be silent. When somebody crosses the IR beam, alarm sounds. If the IR LED and Phototransistor are enclosed in black tubes and aligned perfectly, the range of the circuit is around 1 meter.
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Design your Circuit. Part IV – IR Transmitter


Most of the consumer electronic devices use Infrared remote control for easy operation. The Carrier frequency of such remote control may be 36 kHz or 38 kHz. The Control codes are sent to the receiver of the device in Serial Format. This format is Modulated to the carrier frequency by the On / Off method. In the Remote, the IR signals are generated using an IR LED which emits Modulated IR rays. This part explains the details of IR transmission protocol and the design of IR Transmitter.

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Trick to See Infrared


Have you seen Infrared rays so far? It is difficult to see because it is beyond the spectral response of our eye. Our photosensitive cells in the retina detect only the visible light in the range 450-750 nm. But many animals can see infrared spectrum lying above 900nm.Then what we can do to check whether, the Infrared LED in our project is working or not. A Digital camera can solve the problem. See how it detects the infrared.

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Optoelectronic Devices


Optoelectronic devices are used to activate or deactivate an electronic circuit based on the intensity of light. Besides this general purpose, optoelectronics devices are used in telecommunication, surveillance systems, capturing solar energy etc. Solid state optoelectronic components are used as sensors for detecting visible light, Infrared rays Laser, Ultraviolet rays etc. The note given here explains the different types of optoelectronics devices and their applications.

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