Circuit Project DescriptionThe circuit was designed based on the operation of a digital Sam clock with a programmed ringer attached to its output and made to function using a relay.Terminology 4511 – a BCD to 7-segment decoder driver used to convert the logic states at the outputs of a binary coded decimal (BCD) into signals that will drive a 7-segment display4028 – a BCD to decimal/octal decoder with four inputs that provide a decimal decoded output while a 3-bit binary input provides a decoded octal output used for memory selection control, readout decoding, code conversion, demultiplexing, and address decoding with features such as low outputs on all illegal input combinations, positive logic design, 3V to 18V supply voltage range, and capability of driving one low-power Schottky TTL load over the rated temperature range4081 – a quad dual input AND gate in a 14-pin package generally characterized with small fluctuation, very high impedance, outputs that can sink and source, one output can drive up to 50 inputs, high speed gate propagation time, high frequency, and low power consumption Circuit Explanation
The operation of the circuit comes with the addition and excitation of external units through the use of RL1. In order to provide precise clock values in the HOURS & MINUTES while providing movement in the SECONDS, the method of programming does not remain as it is to meet the desired values. The circuit is being maintained using known materials to make it possible for adding or removing components if needed.
The inputs of IC1-6 using 4511 IC connected with the inputs of IC1-6 using 4028 IC, provides the control of the circuit. The outputs of binary coded decimal to decimal decoder 4028 ICs are connected to dual in-line switches where the numbers from 0 to 9 corresponds to each switch. The numbers are normally indicated in the frame of the switches. The logic level of the output where it matches is transmitted to the corresponding gate comes after, when the switch is closed or turned ON.
As an example, a time indication of 12:05’:46” is made possible by switching ON S7 so that the circuit is supplied with voltage while placing the other DIL switches in the following positions such as S1 to 1, S2 to 2, S3 to 0, S4 to 5, and S6 to 6. A HIGH logic level will be present in the corresponding outputs of IC1-6 when the time is reached and the given example is shown on the 7-segment display.
For the duration of 1 second, all the outputs become HIGH as well as the output of IC8b to drive the transistor Q1. The conduction of Q1 leads to the entry of IC8c at pin 9 which simultaneously changes the state of the output of IC8b to become HIGH for 1 second before shifting to LOW. This action is sufficient to agitate the IC8c & IC8d.
As the switch S7 is opened or turned OFF, the diode LD1 turns OFF while the ringer is also closed. During this state, the RL1 gets open while the buzzer’s sound is stopped and will wait for the next cycle. By closing switch S1, the capacitor C3 is electrified while the level of ringing is adjusted by TR1. The circuit is being supplied by the supply of the basic clock with the consumption depending on the relay to be used.
The theory used behind this circuit plus the capability of adding external devices such as ringers are widely used in the homes, offices, and other establishments that use digital clocks.