am new in electronics engineering and a bit confused about opamps.our lecturer says that an adder circuit like ones used in simple calculators is made using a 741 DIP opamp IC when the inverting op amp is operating in integral mode.so such a circuit an analog electronic or digital?? aren't calculators the most primitive form of a digital computer?? what really draws the line between digital and analogue circuits since all of them are formed by transistors??
Posted on 2011-06-22 12:52:24 by ashken

what really draws the line between digital and analogue circuits since all of them are formed by transistors??

Not all are formed by transistors, although the transistor is the arguably the workhorse of electronic circuits and is thus quite common.

For the difference between AC and DC, I usually draw the line at precision.

Digital electronics use discrete signals, e.g. 0V/+5V, to represent data. In other words, you are using electricity to drive logic gates and the like that perform actions or help direct signals elsewhere as required. Over or under voltage/current shouldn't cause incorrect operation in digital circuits, such as producing junk data... only general failure should occur. When thinking about digital electronics, it is probably easiest to relate it in terms of how binary signals/data are being produced and used.

Analog electronics utilize their electrical inputs to produce electrical outputs or perform actions. A photoelectric cell used to increase or decrease electrical output depending on light input (i.e. automatic potentiometer) is a simple example, where the output can vary from 0V to any number of volts as desired.

Overly simplified: Digital = exacting (logical) voltages, Analog = varying (physical) voltages.

Another factor is that analog electronics can be directly used with AC, e.g. transformers, where-as digital electronics you generally want DC for cleaner discrete signal generation due to precision requirements. However, this is not a hard rule, merely a general observation.
Posted on 2011-06-22 20:32:59 by SpooK
As for the Opamps: Opamps are very often used as 'bridges' (or 'translators') between analog circuitry and digital circuitry. Study opamps well! They're great, powerful and fun :)
Posted on 2011-06-23 07:59:26 by ti_mo_n