Ochala, I. and Momoh, O. Y. and Gbaorun, F.
In this paper, we present the design and construction of a four-hourly digital alarm clock meant for regulating activities of persons in government parastatals, companies, higher institutions and industries. It was constructed using eight 7490 decade counters, eight 7447 decoders, eight seven-segment displays, two 555-timers and two comparators. Results of experimental tests have shown that it has an operating frequency of 1Hz, an alarm interval of 4 hours, alarm duration of 59.4 minutes and works in synchronization with any conventional time-piece. The last three of its characteristics have been found to be greatly resistance dependent and are optimized at a resistance, Rv of 4.8K.
