Digital Clock Without Microcontroller
This circuit is designed to display the time in hours and minutes format, and is wired such that it functions in 24-hour mode. For this purpose, this circuit make use of six 74LS90 decade counters (in figure,IC1 through IC6), four 74LS247 BCD to 7-segment decoders/drivers (IC7 through IC10) and four LT S542 common anode displays (DIS1 through DIS4). In addition, passive components like few resistors, capacitors and push-to-on switches are employed. A 1Hz clock is used to supply the input to the IC1 through pin 14, (1 Hz clock generator circuit is shown in button of article). The output obtained from both of the above mentioned circuits become more accurate with the fact that both circuit take advantage of 32.768kHz quartz crystal.
