02 electronica basica

7/24/2019 02 Electronica Basica

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Electronics

ObjetivesObjetives

What is an electronic circuit?

What kind of power is needed for electronic circuits?

What are the fundamental principles of electronics?

What is the difference between DC and AC voltage?

What are the basic electronic components used in DC

analog circuits?


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Introduction to Electronics


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What is a circuit?

Combination of electronic parts, wires connected between

power sources. It's like a physical program. It's also like settingup dominoes in sequence.


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Basic Electronics

Current (I): Amount of charge passing a given point per unit time

Voltage (V): Electrical pressure or force. If we compare current

to water flowing through a pipe then voltage is the the water pres

Resistance (R): Conductors are not perfect. They resist the flow

of current.


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Basic Components of circuitsBasic Components of circuits


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Resistor

CapacitorWireDiodesLight Emitting Diodes (LED)

BatteryTransistorsMotors

Basic Components of circuitsBasic Components of circuits


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Resistors


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What are resistors?

Resistors provide a specific amount of resistance to

a path in a circuit or wire. Ohm's law is used to calculate theproperties related to resistance.

Ohm's Law: I = V/R

I = Current measured in AmpsV = Voltage measured in VoltsR = Resistance measured in Ohms


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Ohms Law

V = I * R


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Ohms Law


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Resistor Color Code


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Power


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DC

An electrical current can flow in either of two

directions. If it flows in only one direction, it iscalled direct current (DC).

A battery is an example of a DC voltage that

can supply DC current!

Electrical engineers also use the term DC torefer to an average (or constant part of) a

voltage or current signal.


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ACA current which alternates in direction or polarity is

called an alternating current (AC).

The current flowing from a wall outlet is an example of

an AC current!

DC voltage, RMS Voltage, Frequency, Period


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What is a breadboard?

What are they good for?Creatings, organizing, and prototyping a circuit.

Literally started out as a bread board with nails.


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What are LEDs?

Light Emitting Diodes

Diode Symbol + Arrows for lightPoints to ground


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First Circuit

Light and LEDParts:

BatteryResistorLED

Why:Power Source

An LED will light up when enough voltage is supplied but canalso burn out if too much is allowed to pass through. The

resistor will limit the voltage to prevent damage.

Do:Connect Battery, Resistor, LED


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LED Circuit

1 LED Plus resistor

Why have a resistor?Current, limiting.

www.instructables.com


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Series circuit example


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Parallel Circuit example


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Parallel and Series Circuit Example


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Variable resistor: The potentiometer

Voltage dividersTry out the different pots.


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RGB LED

Try resistors out in various combination to make differentcolors. Experiment by adding potentiometers to the leads.


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LED and Photoresistor

Photoresistors change their resistance by the amount of lightdetected.


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What are capacitors?

Capacitor is two separated charges.Known charge up time.Know discharge time.Two major kinds Electrolytic, asymmetric, bipolar

Ceramic, symmetric


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Capacitors in series


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Capacitors in Parallel

They can provide energy, however briefly.They can smooth out a signal.

Attach the battery briefly to fill the capacitor.


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Capacitors in series and parallel


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Make a voltage regulator


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Inductors

Generally - coil of conducting wire

Usually wrapped around a solid core. If no core is used,

then the inductor is said to have an air core.

http://bzupages.com/f231/energystoredinductoruzmanoreengroup6part21464/


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Symbols

http://www.allaboutcircuits.com/vol_1/chpt_15/1.html


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Energy Storage

The flow of current through an inductor creates a magnetic field (right

hand rule).

If the current flowing through the inductor drops, the magnetic field will

also decrease and energy is released through the generation of a

current.

http://en.wikibooks.org/wiki/Circuit_Theory/Mutual_Inductance

Bfield


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Sign Convention

The sign convention used with an

inductor is the same as for a power

dissipating device.

When current flows into the positive side

of the voltage across the inductor, it is

positive and the inductor is dissipating

power.

When the inductor releases energy back

into the circuit, the sign of the current will

be negative.


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Current and Voltage Relationships

1

1

t

t

LL

L

o

dtvL

i

dt

diLv

L , inductance, has the units of Henries (H)

1 H = 1 V-s/A


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Power and Energy

11

1

t

t

LL

t

t

LL

t

t

LLLLL

oo

o

diiLdtidt

diLw

dtiLiivp


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Inductors

Stores energy in an magnetic field created by the electric current

flowing through it.

Inductor opposes change in current flowing through it.

Current through an inductor is continuous; voltage can bediscontinuous.

http://www.rfcafe.com/references/electrical/Electricity%20 %20Basic%20Navy%20Training%20Courses/electricity%20%20basic%20navy%20training%20courses%20%20chapter%2012.htm


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Turn things on and off with a:

ButtonPhotoresistorHall Effect SensorRelayTransistorButtonSwitch


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Transistors

Transistors


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Electronics 40

Transistors

Transistor is a semiconductor device as well - however, it has three terminals

the application of voltage to the input terminal, changes the conductivity between the other two

terminals, and hence controls current flow through those terminals.

Two basic types of transistors, which differ in construction and usage (but not in main purpose)

bipolar junction transistors (BJTs)

field effect transistors (FETs)

Other categorizations - a particular transistor may be described as: silicon, surface mount, BJT,

NPN, low power, high frequency switch.

Semiconductor material: germanium, silicon, gallium arsenide,

Type: BJT, JFET, IGFET (MOSFET), IGBT, "other types"

Polarity: NPN, PNP, N-channel, P-channel

Maximum operating frequency: low, medium, high, radio frequency (RF), microwave

Application: switch, general purpose, audio, high voltage,

Physical packaging: through hole metal, through hole plastic, surface mount


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Electronics 41

Bipolar junction transistor (BJT)

Called bipolarbecause conduction channel uses both majority and minority carriers

for main electric current

first type of transistor to be commercially mass-produced

The three terminals are named emitter, base and collector.

Two p-n junctions exist inside the BJT: collector-basejunction and base-emitter

junction.

described as a current operated device because the collector current is

controlled by the current flowing between base and emitter terminals.


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force voltage/currentwater flow current

- amplification

Understanding of BJT

BJT P ti l A t


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BJTs Practical Aspects

T i t C i it li fi


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Electronics 44

Transistors: Common circuit as amplifier

FET t i t


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Electronics 45

FET transistors

The FET is a three terminal device like the BJT, but operates by a different principle.

The three terminals are called the source, drain, and gate.

The voltage applied to the gate controls the current flowing in the source-drain channel.

No current flows through the gate electrode, thus the gate is essentially insulated from the source-

drain channel. Because no current flows through the gate, the input impedance of the FET is extremely large (in

the range of 10101015 ). The large input impedance of the FET makes them an excellent choice

for amplifier inputs.

T i t


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Transistors

NPN Transistor

O ti l A lfi


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Operational Amplfier

Operational Amplifiers take small voltages and make

them MUCH larger.

Golden Rules (Op amp with negative feedback):

(1) No-current flows into either (+) or (-) inputs.

(2) The (+) and (-) inputs are at the same voltage.

Signal Conditioning


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Signal Conditioning

Electrical engineers use operational amplifiers (Op Amps),

resistors, capacitors, diodes, transistors, etc. to perform

mathematical operations like

Multiplication/Division

Addition/Subtraction

Absolute Value

Natural Log

Filters

Inverting Gain Amplifier


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Inverting Gain Amplifier

Gain = - R2 / R1

Non Inverting Gain Amplifier


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Non-Inverting Gain Amplifier

Gain = (1 + R2 / R1)

Summing Amplfier


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Summing Amplfier

Reed Switch Example


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Reed Switch Example

A reed switch is closed when a magnet is in close proximity.It is symmetric so it can placed either direction.

Tilt ball switch


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Tilt ball switch

Emergency on/off if project tips over.

Motors


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Motors

Try changing the directionof the diode.

What happens?

Relay


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Relay


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Timer with IC LM555


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Timer with IC LM555

http://www.instructables.com/id/47-projects-to-do-with-a-555/

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Luz nocturna automtica


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Luz nocturna automtica

Sensor de temperatura


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p

Sensor de temperatura


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p

Obtenga la expresin de la tensin de salida en funcin de la

tensin de salida del LM35 (y entrada del operacional), Vin.

Conocida la relacin entre la salida del integrado LM35 y la

temperatura, VoLM=10mV/C, y con la expresin de la tensin de

salida del circuito obtenida en el punto anterior, determine los

valores del voltaje de salida para 3 temperaturas diferentes.

Determine la expresin de la temperatura en funcin del voltaje

de salida del circuito.

ReferencesReferences


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www.wikipedia.org

Ingeniera de la Automatizacin Industrial. Ramn Piedrahita Moreno. Ed. Ra-ma.

https://teachmetomake.wordpress.com/basic-electronic-exercises/

Curso prctico de electrnica moderna. Ed. Cekit.


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