Automated Dual output Display
Saturday, April 30, 2011
Automated Dual output Display .This circuit lights up ten bulbs sequentially, 1st in one direc- tion and then within the opposite direction, thus presenting a nice visual impact. In this circuit, gates N1 and N2 form an oscillator. The output of this oscillator is employed as a clock for BCD up/down counter CD4510 (IC2). Depending on the logic state at its pin 10, the counter counts up or down. In the course of count up operation, pin 7 of IC2 outputs an active low pulse on reaching the ninth count. Similarly, during count-down operation, you again get a low-going pulse at pin 7. This terminal count output from pin 7, soon after inversion by gate N3, is connected to clock pin 14 of decade counter IC3 (CD4017) Automated Dual output Display . which is configured here as a toggle flip-flop by returning its Q2 output at pin 4 to reset pin 15. Thus output at pin 3 of IC3 goes to logic 1 and logic 0 state alternately at each and every terminal count of IC2. Initially, pin three (Q0) of IC3 is high as well as the counter is in count-up state. On reaching ninth count, pin three of IC3 goes low and as a result IC2 starts counting down. When the counter reaches 0 count, Q2 output of IC3 momentarily goes high to reset it, thus taking pin three to logic 1 state, as well as the cycle repeats. The BCD output of IC2 is connected to 1-of-10 decoder CD4028 (IC4). In the course of count-up operation of IC2, the outputs of IC4 go logic high sequentially from Q0 to Q9 and therefore trigger the triacs and lighting bulbs 1 through 10, 1 soon after the other. Thereafter, during count-down operation of IC2, the bulbs light within the reverse order, presenting a wonderful visual effect
