8/4/2019 Circuit Ch2

http://slidepdf.com/reader/full/circuit-ch2 1/4

There are basically three types of circuit -- series, parallel, and series and parallel

circuit.

Section 1. Series Circuit

The total voltage is the sum of the voltage on each component.eq 1: V0 = V1+ V2 + V3 +...+ Vn

(In this case, VT = V1+ V2)

The total resistance is equal to the sum of the resistance on each component. eq 2: R 0 = R 1 + R 2 + R 3 +...+ R n 

(In this case, R T = R 1 + R 2)

The total current is equal in every component.

eq 3: I0 = I1 = I2= I3= I4 =...= In

(In this case, IT = I1 = I2)

Section 2. Parallel Circuit.

The total voltage is equal in every component.

eq 4: V0 = V1= V2= V3 =...= Vn

(In this case, VT = V1= V2)

The resistance is equal to the sum of resistance on each component divided by the

 product of resistance of each component.eq 5: 1/R 0 = 1/R 1 + 1/R 2 +...+ 1/R n(In this case, 1/R T = 1/R 1 + 1/R 2) 

The total current is equal to the sum of current in each component.eq 6: I0= I1 + I2 + I3 + I4 +...+ In

(In this case, IT = I1 + I2)

Section 3. Series - Parallel Circuit.

Series-Parallel; many circuit are both series and parallel.

The total voltage is the voltage of series plus the voltage of parallel.

eq. 7: VT = V1 + V2 = V1 + V3 

The total resistance is the resistance of series plus the resistance of parallel.

eq. 8: R T = R 1 + [(R 2R 3) / (R 2 + R 3)] 

8/4/2019 Circuit Ch2

http://slidepdf.com/reader/full/circuit-ch2 2/4

The total current is equal to the current on series and to the sum of the current of 

 parallel circuit.

eq. 9: IT = I1 = I2 + I3 

Section 4. Joule's Law and Power

The heat energy produced by a resistor is

H = I2Rt 

where:

y  H is heat energy in joule,

y  I is the current in A,

y  R is the resistance in ohm, andy  t is time in second.

You can convert joule to calories by multiplying 0.24 on joule.

In a parallel circuit, the least resistance draws the most current and produces the

most heat energy because larger current flows through that component.

The rate of using or supplying energy is called power [P]. The power consumption of 

a resistor is

P = VI = I2R = V2/R  

where:

y  [P] is power in watts,

y  [V] is voltage through resistor in volts,

y  [I] is current through resistor in ampere, and

y  [R] is resistance in ohms.

y  Also,

y

  Power [W] = work (energy) / time [t] (unit of work is joule [J] and time[t] is insecond). 

y  Therefore,

y  work or energy [joule] = power [W] * time [t]. 

y  The unit for energy is watt-second; watt-minute; and watt-hour.

y  1 watt-second = 1 joule 

8/4/2019 Circuit Ch2

http://slidepdf.com/reader/full/circuit-ch2 3/4

Types of circuits

Circuits and components can be divided into two groups: analog and digital. A particular device may consist of 

circuitry that has one or the other or a mix of the two types.

[edit]Analog circuits

Main article: Analog electronics 

Most analog electronic appliances, such as radio receivers, are constructed from combinations of a few types of basic

circuits. Analog circuits use a continuous range of voltage as opposed to discrete levels as in digital circuits.

The number of different analog circuits so far devised is huge, especially because a 'circuit' can be defined as

anything from a single component, to systems containing thousands of components.

 Analog circuits are sometimes called linear circuits although many non-linear effects are used in analog circuits such

as mixers, modulators, etc. Good examples of analog circuits include vacuum tube and transistor amplifiers,

operational amplifiers and oscillators.

One rarely finds modern circuits that are entirely analog. These days analog circuitry may use digital or even

microprocessor techniques to improve performance. This type of circuit is usually called "mixed signal" rather than

analog or digital.

Sometimes it may be difficult to differentiate between analog and digital circuits as they have elements of both linear 

and non-linear operation. An example is the comparator which takes in a continuous range of voltage but only outputs

one of two levels as in a digital circuit. Similarly, an overdriven transistor amplifier can take on the characteristics of a

controlled switch having essentially two levels of output.

[edit]Digital circuits

Main article: Digital electronics 

Digital circuits are electric circuits based on a number of discrete voltage levels. Digital circuits are the most common

physical representation of Boolean algebra and are the basis of all digital computers. To most engineers, the terms

"digital circuit", "digital system" and "logic" are interchangeable in the context of digital circuits. Most digital circuits

use a binary system with two voltage levels labeled "0" and "1". Often logic "0" will be a lower voltage and referred to

as "Low" while logic "1" is referred to as "High". However, some systems use the reverse definition ("0" is "High") or 

are current based. Ternary (with three states) logic has been studied, and some prototype computers

made. Computers, electronic clocks, and programmable logic controllers (used to control industrial processes) are

constructed of digital circuits. Digital Signal Processors are another example.

Building-blocks:

  Logic gates 

   Adders 

8/4/2019 Circuit Ch2

http://slidepdf.com/reader/full/circuit-ch2 4/4

  Flip-Flops 

  Counters 

  Registers 

  Multiplexers 

  Schmitt triggers 

Highly integrated devices:

  Microprocessors 

  Microcontrollers 

   Application-specific integrated circuit (ASIC)

  Digital signal processor (DSP)

  Field-programmable gate array (FPGA)