1.
Resistor
•
Resistor is the electronic component use to
reduce the flow of current.
•
Resistors are available at ¼, ½, 1, 2, 4 Watts
and we need to select the appropriate one we need depending upon the voltage
drop and current flowing through that.
•
In our usual circuits working under 5 to 25
volts we use ¼ W resistors and its size will be small.
•
The value of resistor is being calculated using
the color codes given in that.
•
Variable resistors are the resistors whose value
could be changed
•
They are of mainly two types: Preset type and
Potentiometer Type
•
They are being characterized by the maximum
resistance it could offer.
•
It is mainly used for making potential divider arrangements.
Testing With A Multimeter
•
Select the resistance range in the multimeter
•
Check the resistor with that and get the
resistence reading value from that.
•
Compare that value with the one given in the
color code. If both the vales remains same within the tolerance range, then it
is working fine.
2.
Capacitor
•
Capacitor is the component which could store
electric charge in it for a short time.
•
The value of Capacitor is being measured in
Farads, but as it is a large unit we mainly use micro Farads / nano Farads /
pico Farads.
•
They are of two types :
i.
Electrolytic
Electrolytic capacitors have polarity and it has got higher
capacitance compared to the other. We need to connect it with the correct
polarity else Di-electric breakdown could happen. There is a working voltage
given in the capacitor and it is the maximum voltage under which we could use
that capacitor safely.
ii.
Disk Type:
They have comparatively lower capacitance(in pF range). They
usually don't have any polarity. Values are given in a number code somewhat
similar to the resistor color codes.
•
Variable Capacitors like Trimmers / Gang
Condensers etc are used in circuits like radio tuning (for changing the Natural
frequency of the LC circuit)
Testing With
A Multimeter(Works only with electrolytic capacitor with large capacitance and
should be tested with an analogue multimeter)
•
Select the resistance range in the multimeter
•
First short circuit the two leads of the
capacitor to avoid any charges residing in it.
•
Connect the probes of the multimeter into the
terminals and at that moment you could see a deflection and the pointer coming
back. This is because at the instant when we connect the probes to the terminal of capacitor there
will be a difference in potential and a charging current will flow. Afterwords
the capacitor gets into steady state and no current will be flowing.
3.
Inductor
•
An inductor (also choke, coil or
reactor) is a passive two-terminal electrical component that stores energy in
its magnetic field. For comparison, a capacitor stores energy in an electric
field, and a resistor does not store energy but rather dissipates energy as
heat.
•
Any conductor has inductance. An inductor is
typically made of a wire or other conductor wound into a coil, to increase the
magnetic field.
•
Unit of Inductance is Henry but we usually use
milli Henry as unit.
•
When an intuctor is connected to a circuit the
moment when we switch on the circuit, the current will be zero and when we
switch off the circuit, at that moment it will have the same current as before.
It is the elctrical analouge of inertia in mechanical systems.
4.
Transistor
•
A transistor is a semiconductor device used to
amplify and switch electronic signals and power. It is composed of a
semiconductor material with at least three terminals for connection to an
external circuit.
•
A voltage or current applied to one pair of the
transistor's terminals changes the current flowing through another pair of
terminals. Because the controlled (output) power can be higher than the
controlling (input) power, a transistor can amplify a signal.
•
The transistor is the fundamental building block
of modern electronic devices, and is ubiquitous in modern electronic systems.
Transistor
Pin-Configuration
5.
Diode
•
In electronics, a diode is a
two-terminal electronic component with asymmetric transfer characteristic, with
low (ideally zero) resistance to current flow in one direction, and high
(ideally infinite) resistance in the other. A semiconductor diode, the most common
type today, is a crystalline piece of semiconductor material with a p-n
junction connected to two electrical terminals
•
The most common function of a diode is
to allow an electric current to pass in one direction (called the diode's
forward direction), while blocking current in the opposite direction (the
reverse direction). Thus, the diode can be viewed as an electronic version of a
check valve.
•
In a diode the terminal near which a
line is there will be catode and the other one will be anode.
•
Diode is commenly used for Rectification(Converting AC to DC)
Diode is commenly used for Rectification(Converting AC to DC)
Testing
•
Connect the diode terminals to a multimeter probe as given in the figure.
Connect the diode terminals to a multimeter probe as given in the figure.
•
When it is being forward biased, it
should show very low resistance and in the other case, it should show high
resistance.
Zener Diode:
•
A zener diode is a special kind of
diode which allows current to flow in the forward direction in the same manner
as an ideal diode, but will also permit it to flow in the reverse direction
when the voltage is above a certain value known as the breakdown voltage,
"zener knee voltage" or "zener voltage."
•
Common applications include providing a
reference voltage for voltage regulators, or to protect other semiconductor
devices from momentary voltage pulses.
LED – Light Emitting
Diode
Photo Diode:
•
A photodiode is a type of photodetector
capable of converting light into either current or voltage, depending upon the
mode of operation. The common, traditional solar cell used to generate electric
solar power is a large area photodiode.
•
Photodiodes are similar to regular
semiconductor diodes except that they may be either exposed (to detect vacuum
UV or X-rays) or packaged with a window or optical fiber connection to allow
light to reach the sensitive part of the device.
•
Many diodes designed for use specifically
as a photodiode use a PIN junction rather than a p-n junction, to increase the
speed of response. A photodiode is designed to operate in reverse bias.
6.
IC
•
IC or integrated circuit is a silicon chip in
which millions of other components like resistor, capacitor, transistor were
embedded into.
•
The first integrated circuit was developed in
the 1950s by Jack Kilby of Texas Instruments and Robert Noyce of Fairchild
Semiconductor.
•
Integrated circuits are used for a
variety of devices, including microprocessors, audio and video equipment, and
automobiles.
•
Integrated circuits are often
classified by the number of transistors and other electronic components they
contain as SSI, LSI, MSI, VLSI, ULSI.
•
You should be very careful while using
and soldering ICs and should recheck that you are providing the correct working
voltage for the IC as there are much chances for the IC's to burn off. Even for
small surface mount ICs the static charge residing in your body could destroy
them.
•
Usually people use extra base for
soldering and then put the IC into that after soldering the base.
•
Inductor is a component that cannot be
integrated into an IC.
IC Pin-numbering
The
pins are numbered anti-clockwise around the IC (chip) starting near the notch
or dot.
7.
Transformer
•
A transformer is a device that
transfers electrical energy from one circuit to another through inductively
coupled conductors—the transformer's coils. A varying current in the first or
primary winding creates a varying magnetic flux in the transformer's core and
thus a varying magnetic field through the secondary winding. This varying
magnetic field induces a varying electromotive force (EMF), or
"voltage", in the secondary winding. This effect is called inductive
coupling.
•
If a load is connected to the
secondary, current will flow in the secondary winding, and electrical energy
will be transferred from the primary circuit through the transformer to the
load. In an ideal transformer, the induced voltage in the secondary winding
(Vs) is in proportion to the primary voltage (Vp) and is given by the ratio of
the number of turns in the secondary (Ns) to the number of turns in the primary
(Np) as follows:
•
By appropriate selection of the ratio
of turns, a transformer thus enables an alternating current (AC) voltage to be
"stepped up" by making Ns greater than Np, or "stepped
down" by making Ns less than Np. The windings are coils wound around a
ferromagnetic core, air-core transformers being a notable exception.
•
We usally charecterise the transformer
by the primary and secondary voltages and also the current flowing through the
secondary.
•
Usally there are two types of
transformers: Single tapped and central tapped transformer.
•
In power eliminators with multiple
voltage outputs, we use multi-tapped transformers.
Rectifiers:
8.
Voltage Regulators
•
Regulators are used to give a particular voltage
out put if we give a voltage input above that voltage, within a range.
NB: This is a 5V regulator.
9.
LDR
•
LDR or Light Dependent Resistor is a component
whose resistance changes with the intensity of light falling into it. So this
component is being used as light sensors / detectors.
10. Soldering Basics
Soldering is a process in which two or
more metal items are joined together by melting and flowing a filler metal
(solder) into the joint, the filler metal having a lower melting point than the
workpiece. Soldering differs from welding in that soldering does not involve
melting the work pieces
•
Soldering Iron
Soldering Iron is the main equipment required for
soldering.It is characterised in Watts.Irons of the 15W to 30W range are good
for most electronics/printed circuit board work.
•
Solder and Flux
Solder is a metal or metallic alloy used, when melted, to
join metallic surfaces together. The most common alloy is some combination of
tin and lead.Flux cleans oxides of the surfaces to be soldered.
Steps:
•
Before use, a new soldering tip, or one
that is very dirty, must be tinned. "Tinning" is the process of
coating a soldering tip with a thin coat of solder. This aids in heat transfer
between the tip and the component you are soldering.
•
Warm up the soldering iron or gun
thoroughly. Make sure that it has fully come to temperature because you are
about to melt a lot of solder on it. This is especially important if the iron
is new because it may have been packed with some kind of coating to prevent
corrosion.
•
Thoroughly coat the soldering tip in
solder. It is very important to cover the entire tip. You will use a
considerable amount of solder during this process and it will drip, so be
ready. If you leave any part of the tip uncovered it will tend to collect flux
residue and will not conduct heat very well, so run the solder up and down the
tip and completely around it to totally cover it in molten solder
11.
Multimeter
and Testing Components
•
A multimeter or a multitester, also
known as a VOM (Volt-Ohm meter), is an electronic measuring instrument that
combines several measurement functions in one unit. A typical multimeter may
include features such as the ability to measure voltage, current and
resistance,continuity,capacitance and also for identifying teminals of
transistor.
•
Multimeters are of two types:digital
and analog
•
All digital meters contain a battery to
power the display so they use virtually no power from the circuit under test.
This means that on their DC voltage ranges they have a very high resistance
and they are very unlikely to affect the
circuit under test.
•
Analogue meters take a little power
from the circuit under test to operate their pointer. They must have a high
sensitivity of at least 20k/V or they may upset the circuit under test and give
an incorrect reading.
•
A digital multimeter is the best choice
for your first multimeter, even the cheapest will be suitable for testing
simple projects.
Testing Transistor With Multimeter:
•
Set the meter to its ohms range - any
range should do, but the middle ohms range if several are available is probably
best.
•
Connect the base terminal of the
transistor to the terminal marked positive (usually coloured red) on the
multimeter
•
Connect the terminal marked negative or
common (usually coloured black) to the collector and measure the resistance. It
should read open circuit (there should be a deflection for a PNP transistor).
•
With the terminal marked positive still
connected to the base, repeat the measurement with the positive terminal
connected to the emitter. The reading should again read open circuit (the
multimeter should deflect for a PNP transistor).
•
Now reverse the connection to the base
of the transistor, this time connecting the negative or common (black) terminal
of the analogue test meter to the base of the transistor.
•
Connect the terminal marked positive,
first to the collector and measure the resistance. Then take it to the emitter.
In both cases the meter should deflect (indicate open circuit for a PNP
transistor).
•
It is next necessary to connect the
meter negative or common to the collector and meter positive to the emitter.
Check that the meter reads open circuit. (The meter should read open circuit
for both NPN and PNP types.
•
Now reverse the connections so that the
meter negative or common is connected to the emitter and meter positive to the
collector. Check again that the meter reads open circuit.
•
If the transistor passes all the tests
then it is basically functional and all the junctions are intact.
12. Relays
•
Relays are switching components which could be
turned on / off by giving a voltage across that.
•
There are two types of relays:
i. Industrial Relay : Used to drive High current devices /
circuits.
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