WELCOME running message display
Light emitting diodes are advantageous due to their smaller size, low current consumption and catchy colors they emit. Here is a running message display circuit wherein the letters formed by LED arrangement light up progressively. Once all the letters of the message have been lit up the circuit gets reset. The circuit is built around Johnson decade counter CD4017BC (IC2). One of the IC CD4017BE’s features is its provision of ten fully decoded outputs, making the IC ideal for use in a whole range of sequencing operations. In the circuit only one of the outputs remains high and the other outputs switch to high state successively on the arrival of each clock pulse.
The timer E555 (IC1) is wired as a 1Hz a stable multivibrator which clocks the IC2 for sequencing operations. On reset, output pin 3 goes high and drives transistor T7 to ‘on’ state. The output of transistor T7 1s connected to letter ‘W’ of the LED word array (all LEDs of letter array are connected in parallel) and thus letter ‘W’ is illuminated. On arrival of first clock pulse, pin 3 goes low and pin 2 goes high. Transistor T6 conducts and letter ‘E’ lights up. The preceding letter ‘W’ also remains lighted because of forward biasing of transistor T7 via diode D21. In a similar fashion, on the arrival of each successive pulse, the other letters of the display are also illuminated and finally the complete word becomes visible. On the following clock pulse, pin 6 goes to logic 1 and resets the circuit, and the sequence repeats itself. The frequency of sequencing operations is controlled with the help of pot meter VRI.
The display can be fixed on Veroboard of suitable size and connect to ground of a common supply (of 6V to 9V) while the anodes of LEDs are to be connected to emitters of transistors T1 through T7 as shown in the circuit. The above circuit is very versatile and can be wired with a large number of LEDs to make an LED fashion jewelry of any design. With two circuits connected in a similar fashion, multiplexing of LEDs can be done to give a moving display effect.
Parts List of Running Message Display Projects:Small Project
- IC1 is NE555
- IC2 is CD4017BE
- T1 is 2N3053 (Transistor)
- T2 is 2N3053
- T3 is 2N3053
- T4 is 2N3053
- T5 is 2N3053
- T6 is 2N3053
- T7 is 2N3053
- R1 is 10KΩ 1/4 Watt (Resistor)
- R2 is 330 Ω 1/2 watt
- R3 is 330 Ω 1/2 watt
- R4 is 330 Ω 1/2 watt
- R5 is 330 Ω 1/2 watt
- R6 is 330 Ω 1/2 watt
- R7 is 330 Ω 1/2 watt
- R8 is 330 Ω 1/2 watt
- R9 is 10K Ω 1/4 watt
- Preset 100KΩ (for message speed control)
- C1 is 10μF 16volt (Filter Capacitor)
- C2 is 0.01μF (Disk Capacitor)
- D1 to D28 are IN4007 (Diodes)
- 21 LEDs for W (Letter) color as per required
- 13 LEDs for E (Letter)
- 9 LEDs for L (Letter)
- 10 LEDs for C (Letter)
- 16 LEDs for O (Letter)
- 17 LEDs for M (Letter)
- 13 LEDs for E (Letter) total Leds are 99 pcs.
- 9 Volt Power Supply (need) required as per dc 9volt adaptor.
How its Work?
when Power supply add after all worked finished all parts in pcb with perfact solder and without or missing parts, IC NE555 trigger pulse output from pin no. 3 goes into IC 2 CD4017BE and Ic2 is start output pulse by D22 diode IN 4007 through Resistor R2 330Ω to Base of T7 2N3053 and Tr send pulse via Emeter to Letter “W” throught Groung and W will be Glow, then second pulse from Ic 2 pin no. 2 also pulse out after pin3 from IC2 and same process for Letter “E” , then third pulse from Ic 2 pin no. 4 also pulse out after pin2 from IC2 via T5 2N3053 and same process for Letter “L” , then third pulse from Ic 2 pin no. 7 also pulse out after pin4 from IC2 via T4 2N3053 and same process for Letter “C“, then third pulse from Ic 2 pin no. 7 also pulse out after pin4 from IC2 via T4 2N3053 and same process for Letter “O“, then third pulse from Ic 2 pin no. 7 also pulse out after pin4 from IC2 via T4 2N3053 and same process for Letter “M“, then third pulse from Ic 2 pin no. 7 also pulse out after pin4 from IC2 via T4 2N3053 and same process for Letter “E” glow step by step.
IC2 CD4017BE can gives 10 outpt as per required, in this project 7 output set for W E L C O M E , IC2 have output pin siquense is pin 3,2,4,7,10,1,5,6,9,11. This Projects use only 7 Out put IC2 pin no. 3,2,4,7,10,1,5 and 8th output stop from IC2 so Pin no. 6 joint with pin no. 15 for Reset pulse, so 7 pulse will be operate one by one to Figure’s LED