ece quiz 2

flick it one way to go on and the other way to go off

2 states of switch

a switch is in this state when there is no electrical connection.

there is a very high resistance between wire coming into the switch and the wire going out of the switch

switch state when there is an electrical connection.

there is a very low resistance between wire coming into a switch and the wire coming out of the switch

3 important features to consider when selecting a switch

examples are single pole, double throw

maximum voltage and current

toggle, slide, key, etc

Switch contacts

number of switch contact sets

number of conducting positions, single or double

number of conducting positions, three or more

switch returns to its normal position when released

off position, contacts not conducting

on position, contacts conducting, there may be several on positions

are rated with maximum voltage and current, and there may be different ratings for AC and DC.

The AC values are _____ because the current falls to zero many times each second and arc is ___ likely to form across switch contacts

the maximum current is less for inductive loads because they cause more _____ at the contacts when switch ___.

a simple on-off switch, this type can be used to switch the power supply to acircuit

this returns to its normally open position when you release the button, this shown by the brackets around on. this is the standard door bell switch

returns to its normally close position when you release the button

this switch can be on in both positions, switching on a separate device each case.

often called a changeover switch

may be used as a simple on-off switch by connceting COM and one of the A or B terminals. A and B are interchangeable so switches are usually not labelled

a special version of the standard SPDT switch

it has a third switching position in the centre which is off. are also availble where the switch returns to the central position when released

a pair of on-off switches which operate together, often used to switch mains electricity because it can isolate both the live and neutral connections

a pair of on-on switches which operates together, can be wired up as a reversing switch for a motor

a special version of standard DPDT switch. it has a third switching position in the center which is off. very usueful for motor control because you have forward, off and reverse positions

9 special switches

this looks like a moemntary action push switch but it is a standard on-off switch: push once to switch on, push again to switch off. This is called a _____ ___

are designed to switch fully open orclosed in response to small movements. they are available with levers and rollers attached

a key operated switch, the example is spst

contain a conductive liquid and when tilted this bridges the contacts inside, closing the switch. can be used as a sensor to detect the position of an object. some contain mercury which is poisonous

the contacts of this switch are closed by bringing a small magnet near the switch, used in security circuits, have a glass body which is easily broken

a set of miniature SPST on-off switches, the package is the same size as a standard DIL IC, used to set up circuits

6 pole double throw switch also known as a 6-pole changeover switch, can be set tp have momentary or latching action

means it behaves as a push-push switch, push once for the first position, push afain for the second position etc

have 3 or more conducting positions. may have several poles. popular type has a rotary action and it is available with a range of contact arrangements from1 pole 12 way to 4pole 3 way.

a type of momentary push button switch, are rated by the amound of force needed to push the button and are often flat so that they can be easily inserted within a surface without protruding

an electrical switch that opens and closes under the control of another electrical circuit. teh switch is operated by an electromagnet to open or close one or many sets of contacts

enable a low voltage circuit to switch on a high voltage or high current circuit

Electromagnetic are used in _____ to activated a plunger. When this is switched on, the plunger is attached to the coil.

are often used to turn wheels, gears, cams or pulleys. have two terminals that connect to a battery. The direction of the turning depends on the way the battery wires are connected to the terminals.

are very precise motors that can be made to turn through an exact number of steps.

diode is invented in ____ by ______________________

was contructed with a 2 electrodes in the form of a vacuum tube, Commonly used in DC power supply units as a rectifiers and voltage regulators, clipper, clamper circuit

In 1906, _______ added a 3rd electrode called a control grid and the triode, which is used as amplifier, switch.

The application of triode created a new era in broadcasting with the invention of the _____________ by Pickard, 1912

A material that has an electrical conductivity that is between that of a conductor and an insulator.

can be pure element such as silicon or germanium.

At 0 Kelvin it behaves as an insulator. When the temperature increases, the conductivity of the electricity will increase because its resistance will be lowered.

Advantage of semiconductor material

are the two most common single elements that are used to make Diodes. A compound that is commonly used is Gallium Arsenide (GaAs), especially in the case of LEDs because of it’s large bandgap.

Silicon and Germanium are both group 4 elements, meaning they have 4 valence electrons. Their structure allows them to grow in a shape called the

is a group 3 element while Arsenide is a group 5 element. When put together as a compound, GaAs creates a zincblend lattice structure.

is a process of adding a certain amount of specific impurities called dopants to apure semiconductor to increase its electricity conductivity

2 types of semiconductor

when extra valence electrons are introduced into a material such an __-type material is produced. the extra vlence electrons are introduced by putting impurities or dopants into the _____. the dopants used to create this type material are group __ elements. the most commonly used dopants from group __ are:

material is produced when the dopant taht is introduced is from group 3. coomonly used are:

the construction and symbol of diode is made from a combination of 2 extrinsic semiconductors:

The joint between the P-type and N-type material is called

2 terminals of diode

Near the PN junction the electrons diffuse into the vacant holes in the P material causing a

At the p-n junction, electrons from the n-type semiconductor will be
attracted to the holes in the p-type semiconductor.
As a result, the holes and the electrons at the p-n junction disappear,
forming a layer called

At the same time, the p-type semiconductor becomes more negative
whereas the n-type semiconductor becomes more positive.
This will result a potential difference across the p-n junction. This
potential difference is called the

will prevent the charge carrier from flowing across
the depletion layer

when we bring p-type and n-type a depletion zone is created arounf the junction. This produces a _____, blocking charge flow

The polarity of applied voltage which causes charge to
flow through the diode is called (all
current, almost no volts)

The polarity of applied voltage which can't produce any
current is called .(all volts, almost no
current)

It is the operation region at which the
potential applied to anode is more positive than that applied
to the cathode.

: It is the operation region at which anode
potential is more negative than cathode potential

Part of the reverse region where the
diode impedance is very high, and causes very small drift

: The part of the reverse region where the diode
impedance is very low, and the current passing through the diode is
very high.

: It is also called the knee region. It can be
determined on the I-V curve by the point at which diode starts to
conduct current easily. It is also called the diode
barrier potential and is very near in amplitude to the diode build-in
voltage.

it is a very small current due to drift current in the
diode in the reverse bias region. This current is very low (in the nanoamperes range) due to the high impedance of the depletion region.

: It is the maximum allowable voltage in the reverse
bias region, at which diode resistance changed abruptly from very high
impedance to very low impedance. If the reverse voltage applied on
the diode exceeds this limit, a very high current in the reverse direction
passes through the diode causing in burning it.

The _________________________ of the diode is the quiescent or no-signal condition.
This is obtained graphically and is really only needed when the applied
voltage is very close to the diode’s barrier potential voltage.

rectifying power supply circuit

signal sensor in radar

volatge regulator/ clipper in power supply circuit

indicator light in electronic circuit

osicillator cicuit in oscilloscope

variable capacitor in a tune circuit

light sensor in a remote control unit

focused single color light source in compact disc player

diode application

step fown AC voltage amplitude, isolate equipment from power line

converts an ac input to a unipolar output

convert the pulsating input to a nearly constant dc output

reduce the ripple of the dc voltage

2 types of rectifier

is acircuit that converts an alternation current into a pulsating DC signal

Can produce ripple voltage during both positive and negative input
cycle

2 types of full wave

Circuit that converts the pulsating AC voltage to a DC
voltage.
is to reduce the ripple in the
input waveform.

is very popular because of its low cost,
small size, light weight and good characteristics

types of filter

Stabilize the output voltage.
Reduce the ripple at the output voltage of the filter
circuit.