3. intelligent Car Battery Charger

ABSTRACT

The life of a Lead acid battery is greatly affected by its charging and discharging current rates. The maximum life can be ensured for a battery if the battery charger design is strictly based on the charging profile given by the manufactures. Most of the lead acid battery (sealed and unsealed) charging cycle requires a constant current the constant voltage and trickle charging. In this Car battery charger several techniques are used to save the battery and extend its life. Battery monitor always displays the battery voltage. Voltage controller module detects battery low conditions and battery full charged conditions and controls the charging mechanism. The battery charger circuitry is implemented using PWM technologies, which enhances the charger efficiency and stabilize the charging process. The charging rate can be controlled automatically and manually. Audio and visual alarms indicate the various conditions. This Battery charger can be used to charge car battery with 100AH capacities

BLOCK DIAGRAM

2. Class Room announcement System

ABSTRACT

Nowadays the main design criteria for electronic product designing are maximum performance versus coat.  Class Room Announcement system is simple audio broadcasting make use of power line audio communication system. Communication system consists of one master unit (transmitter) and more than 2 slave units. The master unit is built with an AT 89s51 microcontroller .MU has a sound input (from mic unit) and class room selector unit. With the help a dedicated code MU can unicast or broadcast to its slave units. The SU  reproduces the sound signals transmitted by MU only when it is addressed by its own code assigned by the MU. Since the slave units are communicated with the master unit via power lines we can ensure high quality, security and low coast. Future expansion to this project  is  a message sending  mechanism for  text  messages  .

Block Diagram 

1.Power line audio communication system

ABSTRACT

The overall cost and performance of a communication system depends on the communication media.  In Power Line Communication System the power supply lines itself used as the media in addition to Power supply. So the Transmitter and Receiver units requires power its supply only. For power line communication systems the frequency of operation is limited to a range 50 kHz to 500 kHz in order to avoid the RF radiation from the power line. The input signal (50 Hz to 15 KHz) is amplified and AM/FM modulated with a carrier frequency around 445 KHz. The modulated signal output is band limited to 500 KHz and is send via signal coupler network to 230V KSEB supply. The Range (Distance between the Transmitter and Receiver units) can be expected up to 500 meters with Reasonable SNR if AM is used. The Range and SNR can be improved with FM .Receiver unit is a signal extractor network followed with AM/FM modulator  and amplifier .This Device can be used for a lot of applications like loudspeaker extension between rooms, FM/AM Bugs, calling alarms, Home security systems. Power line data communication is the future expansion for this device with small changes in the circuitry. 

Block Diagram