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An electronic circuit is a closed path formed by the interconnection of electronic components through which an electric current can flow. The electronic circuits may be physically constructed using any number of methods. Breadboards, perfboards or stripboards are common for testing new designs. Mass-produced circuits are typically built using a printed circuit board (PCB) that is used to mechanically support and electrically connect electronic components.

Electronic circuits can display highly complex behaviors, even though they are governed by the same laws of physics as simpler circuits.

Electronic circuits can usually be categorized as analog, discrete, or mixed-signal (a combination of analog and discrete) electronic circuits.

For lessons on the topic of mind Circuitry, follow this link.


a. F. circuit, ad. L. circuitus going round, f. circu(m){imac}re, f. circum round + {imac}re to go.]


  • The line, real or imaginary, described in going round any area; the distance round; the compass, circumference, containing line or limits.


1382 WYCLIF Ecclus. xliii. 12 See the bowe..He cumpaside heuene in the circuyt [1388 cumpas] of his glorie. c1386 CHAUCER Knt.'s T. 1029 The circuit a myle was aboute Walled of stoon and dyched al with oute. c1400 MANDEVILLE xviii. 187 nyghe 2000 Myle in circuyt. 1570 BILLINGSLEY Euclid I. iv. 14 The circuite or compasse of a triangle is a line composed of all the sides of a triangle. 1593 SHAKES. 3 Hen. VI, I. ii. 30 To weare a Crowne, Within whose Circuit is Elizium. 1652 NEEDHAM Domin. Sea Advt. 2 The circuit of this Sea..must contein above 1200 miles. 1704 ADDISON Italy (1766) 124 Sheltered with a noble circuit of woods and mountains. 1847 GROTE Greece IV. II. lii, A rude Circuit of stones, of unknown origin.


Analog circuits

Analog electronic circuits are those in which signals may vary continuously with time to correspond to the information being represented. Electronic equipment like voltage amplifiers, power amplifiers, tuning circuits, radios, and televisions are largely analog (with the exception of their control sections, which may be digital, especially in modern units).

The basic units of analog circuits are passive (resistors, capacitors, inductors, and recently memristors) and active (independent power sources and dependent power sources). Components such as transistors may be represented by a model containing passive components and dependent sources. Another classification is to take impedance and independent sources and operational amplifier as basic electronic components; this allows us to model frequency dependent negative resistors, gyrators, negative impedance converters, and dependent sources as secondary electronic components. There are two main types of circuits: series and parallel. A string of Christmas lights is a good example of a series circuit: if one goes out, they all do. In a parallel circuit, each bulb is connected to the power source separately, so if one goes out the rest still remain shining.

Discrete circuits

In digital electronic circuits, electric signals take an discrete values, which are not dependent upon time, to represent logical and numeric values. These values represent the information that is being processed. The transistor is one of the primary components used in discrete circuits, and combinations of these can be used to create logic gates. These logic gates may then be used in combination to create a desired output from an input.

Larger circuits may contain several complex components, such as FPGAs or Microprocessors. These along with several other components may be interconnected to create a large circuit that operates on large amount of data.

Examples of electronic equipment which use digital circuits include digital wristwatches, calculators, PDAs, and microprocessors.

Mixed-signal circuits

Mixed-signal or hybrid circuits contain elements of both analog and digital circuits. Examples include comparators, timers, PLLs, ADCs (analog-to-digital converters), and DACs (digital-to-analog converters).

Three Basic Parts

Energy source - converts nonelectric energy into energy. Examples are batteries and generators.

Output device - uses electric energy to do work. Examples are motor, lamp, or display.

Connection - allows electric current to flow. Examples are wire and cable.

See also