Hall Sensor. Design note 8

Hall sensor is a device that generates output current based on the magnetic field in its proximity. When a current carrying conductor is placed in a magnetic field, a voltage is generated perpendicular to the current and the field. This phenomenon is called as Hall Effect. The Hall sensor has a thin semiconducting material called Hall element. A current is passed through the Hall element in a direction perpendicular to the output connections. In the absence of a magnetic field, current distribution is equal without any potential difference across the output. When a perpendicular magnetic field is applied, a force called Lorentz force disturbs the current distribution and a potential difference develops across the output. The output voltage is called as Hall voltage (VH ). Lorentz force is the force acting on the moving charge carriers in a magnetic field.
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PIR Light Switch.Design note 7


PIR Based Light switches are now available to use as Motion detectors. When somebody passes through its detection area, the load such as light or electric alarm turns on. The delay time can be adjusted from 30 seconds to 3 minutes. After the delay time, the load turns off. The sensitivity can also be adjusted up to 10 meters. The unit consists of a PIR sensor module and a Tric controlled circuit for AC operation. It uses a transformerless power supply to make the unit compact. Load can be any AC device like bulb, Tubelight, CFL or an AC bell. It also has an LDR based circuit for actvating the circuit only at night. It is very easy to fix the unit and only two wires are needed for connection.It costs Rs. 350 to 550 depending on the make.
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RF Wireless Module. Design Note 6

433 MHz Wireless moduleRF Wireless Module pair 433 are excellent Transmitter ( Tx) and Receiver ( Rx ) transmitting signals  in the UHF band  at 433 MHz . These modules can be used to transmit and receive data, voice or other signals like IR pulses to remote places. The Wireless modules works off 5 volt DC and a regulated power supply is required. It is useful in various Microcontroller applications.
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