The PC (Personal Computer) control AC appliance is used to control the 220V AC devices with the help of the PC. Personal computer used as a remote and the switching action is done with the help of the computer. This project is very useful to understand the logic of the SCADA (Supervisory Control and Data Accusation system). For better understanding the project is first divided into the two sections first one is block diagram and second is circuit diagram. Therefore first start with the help of block diagram. Block diagram of the PC (Personal Computer) Control AC Appliance is divided into the following section.
- Computer Serial Port
- Level Converter
- Relay Driver
Block diagram of the PC (Personal Computer) Control AC Appliance
Computer Serial port
The computer serial port is which is called serial communication is also used for the data transmission. When the data is written on the computer software is send through this serial port. Now the output of the serial port is send to the level converter.
The level converter is used to convert the voltage level of the computer to the digital voltage level. The digital hardware work the digital logic voltage and computer serial communication port work RS232 voltage level signal. So the voltage level is used to manage this voltages, after that the is send to the microcontroller.
The microcontroller is used to convert this serial input signal to the parallel signal. It also convert the signal for the processing the relay driver hardware so that load can be control. Therefore the output of the microcontroller is feed to the relay driver.
The relay driver is used to drive the relay and provide the proper power for the switching. It amplifies the voltage and current up to desirable level which drive the relay. The output of the relay driver is feed the relay.
The relay is used to control the AC appliances with the help of the digital logic signal which is get from the microcontroller. The relay is work as an isolator as well as a switch. The load is connected to the output of the relay.
Any AC appliances are work as a load in this project. The AC appliances like bulb, washing machine, fan, TV, cooler etc. can be used for their switching. The circuit diagram of the PC (Personal Computer) Control AC Appliance is divided into the following section.
- Computer Serial Port (RS232)
- Level Converter (MAX232)
- Microcontroller (AT889S51)
- Relay Driver (ULN2003)
- Relay (12V)
- Load (BULB)
Circuit Diagram of the PC (Personal Computer) Control AC Appliance
Computer Serial Port (RS232)
The 9 pin serial communication (DE9 type) port is used to interface the computer software and hardware. The communication port which is also called RS232 serial port is work on the -3Volt to +25Volt logic signal. The microcontroller is work on the TTL/CMOS logic which works on the 0 Volt to +5Volts. So that a voltage level converter is used to convert this voltage to make compatible with these voltage signal.
Level Converter (MAX232)
The level converter IC MAX232 is used to convert the TTL logic to the RS232 voltage level signal and RS232 voltage level signal to the TTL logic signal. It consist two transceivers so that at a time two transmitter and receiver can be connected at a time. Here we require only single transceiver. The computer is used as a transmitter and hardware is used a receiver. Now the output of the level converter is send to the microcontroller.
The AT89S51 microcontroller is used for the decision purpose device. It receives the ASCII signal and then sends to the port 2 on the output. The input signal is receive through the receiver pin (pin number 10) of the microcontroller and sends to the output on the port 2 (pin number 21 to 28). To check this signals on the port 2 a group of LED’S is also connected.
Relay Driver (ULN2003)
The relay driver IC ULN2003 is used to drive the relay from the microcontroller signal. It receive the low voltage signal from the microcontroller and amplifies it at the desirable level which drive the relay properly. The input is receive from pin number 1 to 4 and send it to the pin number 16 to 13 respectively. The relays are connected between pin number 13 to 16.
Rely (12 Volt)
The 12 Volt relay is used to control the AC appliances (bulb). The switching action is control from the computer input signal and according to that signal appliances are control. The relay also provides the isolation between the logic circuitry and AC signal.
Bulb (220 V, AC)
The bulb is used in this project as load. The switching action output is check on the bulb. So here with help of our PC (Personal Computer) we can control any AC Appliance’s.