Here is a simple circuit that displays a “HAPPY NEW YEAR” message. The alphanumeric display can be fitted anywhere in your home .The circuit is built around [[wysiwyg_imageupload::]]555 ICs, twelve KLA511 common-anode alphanumeric displays(IC1 to IC12) and a few discrete components. IC 555 functions as timer circuit and message is displayed for two minutes which is pre-determined by making the 555 work into monostable multivibrator mode. In this mode, one state of 555 based timer has a fixed duration, while other state surfaces up only when an interrupt is witnessed.KLA511 displays are a popular category of alphanumeric LED displays that consume low power and can work for longer duration without generating excess amount of heat. Each KLA511 unit comprises of 7 LEDs and has a common-anode circuit arrangement which along with some passive components, gives optimized display outputs. Keep on reading to find out how the circuit is constructed and what makes it work.
The Global System for Mobile (GSM) communication is the Second Generation of mobile technology. Although the world is moving towards Third and [[wysiwyg_imageupload::]]Fourth generation but GSM has been the most successful and widespread technology in the communication sector. GSM technology paved a new way for mobile communication.This project explains the interfacing of a GSM Module with a PIC microcontroller. It also covers a way to dial a particular GSM mobile number as well as send a message to it using AT Commands with the help of PIC18F4550.As explained earlier (refer GSM interfacing with 8051), a line converter MAX232 is employed to convert the RS232 logic data of GSM Module to TTL logic so that it can be processed by the microcontroller. In this project, instead of RS232 logic data, TTL logic output has been taken and thus PIC18F4550 has been directly connected with GSM Modem without any line converter in between. The following diagram shows the TTL input and output of GSM modem used.