DIGITAL STOPWATCH by Using 7segment

Written By faiq aprilian on Friday, August 3, 2012 | 3:14 PM

A digital stop watch built around timer LM555 and 4-digit counter MM74C926 with multiplexed 7-segment LED display. MM74C926 consists of a 4-digit counter, an internal output latch, npn output sourcing drivers for common cathode, 7-segment display and an internal multiplexing circuitry with four multiplexing outputs. The counter advances on negative edge of the clock. The clock is generated by timer LM555. The circuit works off a 5V power supply. It can be easily assembled on a general-purpose PCB. Enclose the circuit in a metal box

with provisions for four 7-segment displays, rotary switch S1, start/stop switch S2 and reset switch S3

First, reset the circuit by pressing S3 so that the display shows "000". Now open switch S2 for the stop watch to start counting the time. If you want to stop the clock, close S2. Rotary switch S1 is used to select the different time periods at the output of the astable multivibrator.

Circuit Diagram of Digital Stop Watch

Skema Rangkaian Stop Watch Digital Tampilan 7 Segmen

7 segment
Seven Segment is 8 pieces of LED array is arranged in such a way that was shaping up to 7 segments and 1 point that can be used to show the pattern numbers and some letters. there are two types of seven-segment LED Seven segment of the Common Anode (CA) and Common Cathode (CC).

Seven Segment

On picture above is the layout, naming seven segment each segment and 8 illustrate the fruit is packed as the LED array LED Common Anoda (CA) and an array of LED Common Cathode (CC). segemen seven controllers can be done directly, or through a pattern such as a driver IC 74LS47 to seven segment CA and 74LS48 to seven segment CC.


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