My Light Diagram

author : Pafilis Ioannis - Aristotle University of Thessaloniki Department of Electronics and Telecommunications In the present article , we will describe the function of a digital stopwatch , 0 – 99 sec . The function of the stopwatch , relies in the use of 4 integrated circuits, which in this case belong to National Semiconductor ( http :// www . national . com ). It is obvious that other integrated circuits can be used to achieve the same result, however in this case we have used the following parts : Α. 1 x CD4060BM (14 stage ripple carry binary counter) B. 1 x CD4040BM (14 stage ripple carry binary counter) C. 1 x MC14518B (BCD counter) D. 2 x MC14511B (BCD to seven segment driver) E. 2 x 7 segment LED displays The circuit that has been used is shown in picture 1. Through the experimental part we will explain each of the parts function, but in order to have a notion of the basic idea, let just say, that this circuit besides the 5V...

Now Build a Digital Stopwatch 0-60sec By using the same circuit of the Digital Stopwatch 0-99sec , we can add an AND gate, and transform the 0 – 99sec stopwatch to a 0 – 60sec stopwatch.We must find a way to control the RESET function of the BCD counter, which is responsible for the counting of the seconds. As we studied above, the circuit resets when we have 99 to 100, that is 1001 1001 à 0001 0000 0000. To make a transformation successfully we must force the pulse from 59 to 60 0011 1001 à 0100 0000 on the output of the BCD counter. By placing the AND gate, with its inputs on the Q1 and Q2 of the BCD counter of the decades, we make sure that when the gate closes, the RST input of the BCD counter will be set to logical “1”, which on its turn, will force the circuit to start over. The transformed circuit appears in picture 2.