14-08-2012, 01:01 PM
PRE PAID ENERGY METER
PRE PAID ENERGY_program[1].docx (Size: 702.5 KB / Downloads: 626)
IC 8870 , DTMF DECODER IC.
IC 8870 PROVIDE A GSM INTERFACE WITH THIS CIRCUIT. DUE TO THIS IC WE DECODE THE CALL THE PROVIDE A BALANCE IN THE ENERGY METER AUTOMATICALLY.
IC 74154 IS A BCD TO DECIMAL DECODER ATTACH WITH THE MICROCONTROLLER TO INTERFACE WITH THE DTMF DECODER
5 VOLT REGULATED POWER SUPPLY TO PROVIDE A REGULATED VOLTAGE TO THE MICROCONTROLLER UNIT.
24C02 MEMORY ( 8 PIN).
• In this project we use one 5 volt regulated power supply.
With the help of the 7805 regulator we provide a 5 volt regulated
power supply. Output of the regulated power supply is displayed
by the resistance and led in series. . IC 8870 is here as a dtmf
decoder ic. This ic decode the output and converted into bcd
signal. Pin no 2 and 3 is connected to the resistor and capacitor
network. With the help of this circuit we insert a dtmf input in the
decoder. Here we attach a handsfree from the mobile phone. Pin
no 7 and 8 is connected to the external crystal. With the help of
this crystal we decode the signal. This crystal is a fixed value of
the 3.58 Mhz. Output is available on the pin no 11,12,13,14 . his
output is bcd output from the circuit. One led with resistor is
connected with the pin no 15 .This signal is a ack of decoded signal. If the signal is decoded then this led is on. This signal further connected to the base of the npn transistor and provide a signal to enable pins of the ic 74514. IC 74154 is a bcd to decimal decoder. Output of the 74154 is further connected to the microcontroller directly. IC 74154 is 4 to 16 line decoder ic. Here we use only two output of the 74154 because we insert only two value from the gsm phone. Output of the 74154 is connected to the microcontroller directly. Here we use ic 89s51 as a main controller. Pin no 40 of the ic is connected to the positive supply. Pin no 20 is connected to the ground pin. Pin o 18 and 19 is connected to the external crystal oscillator. Pin no 39 to pin no 32 is connected to the lcd data pins. Here we use 8 bit data from the controller to provide a data to the lcd. LCD control pins RS, RW, enable is connected to the pin no 26,27,28.
Memory is connected to the pin no 23,24 of the ic. Pin no 23 and 24 is connected to the non voltaic memory. Pin no 8 is connected to the positive supply. Pin no 7 is connected to the ground. . Use of memory is to retail all the data of variable, which store the data of balance and unit value. When light is off then data is to be saved into non volatic memory.
When we press the start switch then if the balance is available then output is
available on the pin no 23. On this pin we connect a relay coil. Relay switch on the load circuit. If the load is connected then load provide a feedback by the feedback transformer circuit. This feedback is when connected to the controller then controller decrement the amount. Here we not showing the actual load cutting amount, we just show the concept. If the amount is below 5 R/s.
VOLT REGULATED POWER SUPPLY CIRCUIT.
In this project firstly we use one step down transformer. Step down transformer step down the voltage from 220 volt Ac to 12 volt Ac. This Ac voltage is further converted into DC with the help of rectifier circuit. In rectifier circuit we use four diode. All the diodes are arranges as a bridge rectifier circuit. Output of this rectifier is pulsating Dc. To convert this pulsating DC into smooth dc we use one capacitor as a filter components. Capacitor converts the pulsating Dc into smooth DC with the help of its charging and discharging effect.