Semester 2

Saturday, 5 November 2011
Subject : DIGITAL ELECTRONICS



WHAT IS DIGITAL CIRCUIT


Figure A

A digital device operates with a digital signal. Digital signals produce discrete voltage levels commonly referred to as HIGH and LOW. The generator produces a square waveform as in Figure A. The digital signal is only at +5 volts or at 0 Volts.



The voltage at point A moves from 0 to 5 V. The voltage then stays at +5 volts for a time. At point B the voltage drops immediately from +5 to 0 volts. The voltage then stays at 0 v for a time. There fore only two voltages are present in a digital electronic circuit. The waveform voltages are labeled HIGH and LOW. The HIGH voltage is 5 volts, the LOW voltages is 0 volts. Therefore circuits that handle only HIGH and LOW signals are called digital circuits. Digital electronics is the world of logical 0s and 1s. For example Digital Multimeter (DMM) – digital measuring device. Digital signal could also be generated by a simple on – off switch. Example in Transistor turning on and off.










 

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