IJSRP, Volume 5, Issue 12, December 2015 Edition [ISSN 2250-3153]
Auwal Mustapha Imam
This paper presents the design of a Digital Clock that displays 24-hours, minutes and seconds. A time-based oscillator containing a 555 timer Integrated Circuit (IC) in an astable mode with a frequency of 1Hz provides the clock pulses for the seconds display. On each of the Dual Seven-Segment (7-Segment) displays for hours, minutes and seconds, Binary Coded Decimal (BCD) counters converts each clock pulse received into a 4 bit 8421 synchronous logic output. Display decoders/drivers connected to each 7-Segment display decodes the 4-bit 8421 logic and converts it to a 7-Segment display codes. The dual-7-Segment displays of each of the hours, minutes and seconds output the figures 0 to 9 according to the set time. The clock is designed to work with the stabilized 9V DC voltage power supply.