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Basic Electronics:REVIEW

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Introduction to

Electronics

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Basic concepts

Basic concepts

Signals

Amplifier

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Signals

Signal sourceTransducers are the devices which canconvert the non-electric signal to electricsignal, or vice versa. Signal source is thetransducer witch can produce electric signal.Representation of the signal source

Thvenin form Norton form

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Representation of the Signal Source

Two alternative representations of a signal source:(a) the Thvenin form(b) the Norton form

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Time-Domain Representation of Signal

An arbitrary voltage signal v s(t ).

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Time-Domain Representation of Signal

Sine-wave voltage signal of amplitude V a and frequency f = 1/ T Hz.The angular frequency = 2 f rad/s.

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Time-Domain Representation of Signal

A symmetrical square-wave signal of amplitude V .

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Frequency-Domain Representation of Signal

The frequency spectrum of an arbitrary waveform is continuous functionof frequency. It means the spectrum contains all possible frequencies.

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Frequency-Domain Representation of Signal

The frequency spectrum of the periodic square wave consists ofdiscrete frequencies.

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Analog and Digital Signals

Analog signalThe magnitude of analog signal can take on any valueand exhibits a continuous variation over its range ofactivity.Digital signalThe representation of digital signal is that of asequence of numbers, each number representing thesignal magnitude at an instant of time.Sampling

ADC and DAC

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Sampling

Sampling the continuous-time analog signal in (a)Results in the discrete-time signal in (b).

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ADC and DAC

Block-diagram representation of the analog-to-digital converter (ADC).

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Amplifier

A voltageamplifier fed witha signal v I (t ) andconnected to aload resistance R L.

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Amplifier

Transfercharacteristic of alinear voltage amplifierwith voltage gain Av.

The straight linemeans the amplifier is

a linear amplifier.

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Amplifier

An amplifiertransfer characteristicis linear except foroutput saturation.

Output waveform isclipped off.

Nonlinear distortion

exists.

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Amplifier

An amplifier transfercharacteristic thatshows considerablenonlinearity.

Nonlinear distortion

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Amplifier

To obtain linear operationthe amplifier is biased asshown

The signal amplitude iskept small.Observe that this

amplifier is operated from asingle power supply, V DD .

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Engineering Prefixes

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Schematic Circuit Symbols

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Analog multimeter Hand-held digital multimeter (DMM)The quantity being measured is indicated on the

scale selected by the rotary switch.

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How to measure

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Analog multimeter: The quantity being measured is indicated on the

scale selected by the rotary switch.

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Resistance

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Types of Resistors

Fixed Resistors

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Variable Resistors

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Color Coding of Resistors

Dung sai

Temperature coefficient of resistance(TCR) parts per million per degreeCelsius. The abbreviation is ppm/ C. Anold fashion carbon composition resistormay have a TCR of over 1000 ppm/ C and

a 10k resistor would change around 100ohms for a 10 C in temperature.

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Measuring Resistance The Ohmmeter

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Thermistors

A thermistor is a two-terminal transducer in whichresistance changes significantly with changes in

temperature

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Photoconductive Cells

Photoconductive cells or photocells are two-terminal transducers which

have a resistance determined by the amount of light falling on the cell.

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Capacitor

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Inductors

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Test and Measurement Instruments

HORIZONTALVERTIC AL TRIGGER

5 s 5 ns

POSITION

CH 1 CH 2 EXT TRIG

AC-DC-GND

5 V 2 mV

VOLTS/DIV

COUPLING

CH 1 CH 2 BOTH

POSITION

AC-DC-GND

5 V 2 mV

VOLTS/DIV

COUPLING

SEC/DIV

POSITION

SLOPE

+

LEVEL

SOURCE

CH 1

CH 2

EXT

LINE

TRIG CO UP

DC AC

DISPLAY

INTENSITY

PROBEC OMP5 V

The front panel controls for a general-purpose oscilloscope.

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