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.
This simple message display can be used to display any message such as warnings, wishes, address notifications etc. as it will automatically turn ON at night or in [[wysiwyg_imageupload::]]dark. This circuit is based on CD4060 IC, LDR and few more components so that we can be easily made and can be gifted to friends. Here total of 12 bright LED glow inside the four segments (I through IV as shown in fig below) of the message plate to display different message. We can use bright white LED’s or different color LED’s to indicate different words. In this circuit, different segments glow for different duration of time. IC CD4060 is 14 stage ripple carry binary counter, divider and an oscillator. Its built in oscillator is main feature of this IC, so it can be used in numerous applications like flasher, clock generator in timer circuits. The resistance of LDR is very high in darkness, which reduces to minimum when LDR is in light.
This article presents an interesting approach for sound activated display system. This system displays two different messages for odd and even number of [[wysiwyg_imageupload::]]sounds. When the sound is produced for the first time the first message is displayed on the LCD. At the second sound, a second message is displayed. The first message reappears at the third sound. Thus alternate messages are displayed every time a sound, say clap, is detected by the system. The project is build around the 8051 microcontroller (AT89C51) along with LCD and a condenser microphone.The circuit consists of four major modules, namely, a sound sensor, an amplifying circuit, a control circuit and a display module. A switching circuit is also employed after the amplifier. Any sound, say clap, is detected by a microphone (condenser mic) which acts as the sound sensor. This mic is connected to a two stage transistor amplifier. The mic output is thus amplified to a suitable level so that it can be detected at the TTL logic.