RESISTOR
Hello friends, today in this article I will explain what is resistor and how to use them in your circuits and we will also discuss about the Resistive loads and some practical examples which we use them in our day today life.
Resistor are
used everywhere starting form the small circuits to integrated circuits like
IC’s even our computers processor has thousands of resistors. Even the wire
which we use for connection purpose has resistance of 0.001 ohms its actually
depends on the length and the radius of the wire but super conductors there are
special they have zero resistance under suitable conditions.
What
is a resistor?
The word
resistor means it resist something ,i.e not allowing to pass through or blocking the
passage. In electronics its used to limit the current. Resistor is
a current limiting device.it has two terminals, it limits the flow of current
by dissipating excess energy in the form of heat. They are often use in electronics
for current limiting, Transistor biasing, feedback loops, potential divider
etc.
This
is the image of a virtual resistor.
Various
types of resistor which I have collected so far
Making your own resistor (DIY resistor):
Friends we can make our own resistor by simply
wounding a copper string or any other type of conductor over a non-conducting
core (insulator). I have tried to make on but finally I found it’s a total
waste of time. It’s better to buy a new one.
DIY (do it yourself) resistors have several
disadvantage.
It consumes our precious time. (1 kilo ohm
resistor would requires nearly 100-1000 turns or more depending up on the wires
diameter and conductivity of the material)
By making one DIY resistor you are not
gone save money. Material cost will be much
higher than
actual resistor.(In India 1 resistor is lesser than 1 rupees).
But you can
make resistors with 10-30 ohm with high wattage (10-50).
I
had a 2.2ohm 10 watt resistor when I break it I got this
The broken
one consist of 14 windings of conducting wire, conductor type and diameter of
wire is very important while designing a resistor. You can use old stuff to
make resistor of your own for high watt resistor you need a conductor which has
large diameter but for that u have to wind 50 turns.
This DIY
resistor is only recommended in case u cannot get certain wattage resistor in
your local
shop. Know a day’s you can get all you want through online stores.
At low cost.
Types
of load:
Loads are
broadly classified into inductive load, capacitive load, last but not the least
resistive load.
Today our topic is resistor so lest see what is resistive load.
Resistive load:
Know a day’s
resistive loads are not used because of its poor efficiency. Resistive loads just
consist of a resistor. If you are not familiar with a resistive load here some example
which shows what are the
resistive load which we use in our house.
Example
1:
Light
bulb
We are familiar with a light bulb and where it
is used but have you ever imagined how efficient it is. Well I will show how
efficient they are before that lets have a look at the old style light bulb.
It this type
of light bulb electricity is made to flow through the thin wire which is called
the filament.
When current
flows through the resistor energy is dissipated in the form of heat. When a
metal becomes hot its start to glow.
This
principle is used in this electric bulb but another question arises when metals
like iron, silver, Gold will melt at high temperature. Because this drawback
they use tungsten material because they can handle high temperature without
melting. This thin wire are protected under a glass shell in order to protect
the filament and to prevent it from reacting with air. Generally they are less
reactive when compared with copper and other metals.
Example
2:
Old style water heater, iron box hair
dryer etc. Still most of the iron box uses the same principle. They use Nichrome
wire as heating element.
this contains nichrome wire which gets hot and so hot air comes out of it.
Nichrome
wire are unique they have high resistance when compared to other metals. This image
shows the resistance of a Nichrome wire of 1 meter length. (1 meter = 100 cm).
If you want
to check the resistance of any conducting wire use your multimeter and adjust
it for measuring resistance. As shown in this image.
Example
3:
If you really love electronics you might
have some soldering irons lying around I got three of them and tried to make
one DIY soldering iron. Look at this image. My DIY soldering iron is not good
but its works.
Even this
irons uses nichrome wire.
How
to use a resistor?
As we know resistor is used to limit current.
If I want to add a current limiting resistor to a led circuit. Then I have to do
some calculations for inserting a proper resistor if your resistor value is too
high then your led will not glow sometime it will glow dim. Similarly when
resistor value is low then led will be
destroyed.
I had a 1
watt led which is operated at
V
= 3.6 volt (led voltage)
Power = 1 watt
We know
voltage and power consumption of this led, but still current value is unknown
let’s make use of ohms law to determine the current consumption of the SMD led.
Current
I = power/volt
= 1/3.6
= 0.2777 Amp
To determine
the resistance which to be added when the supply (source is 5 volt)
5
V (power source) – 3.6 V (led voltage) = 1.4 V
1.4 volt is
the excess voltage which we have to remove by adding suitable resistor.
Using ohms
law
V=I*R
Where,
V = excess voltage (1.4 volt
according our problem)
I = led current (0.277 Amp)
R = unknown
Let’s
get started
V = I*R
1.4 = 0.277(This flows through the
resistor)*R
R = V/I = 1.4/0.277
= 5.05 ohms
This 5 ohm
resistor will remove the excess 1.4 volt which is not required but actually
they limit the current but due to the proportionality voltage reduces.
Note:
standard resistor can handle load of around 0.25 watt but our led is 1watt. Or
simply we must use a resistor which can allow 0.277 amps to pass through
standard resistors can only allow 0.25 amps its recommended to go for 1 watt
resistor or even higher.
Resistance
of a resistor depended on colour code.
When you see
a resistor they have some ribbons with different colour. Each colour determined
its resistance value if we know the colour chat of the resistor then it will be
easy for us to determine the resistance of a given resister
Schematic
of a simple led circuit is given.
Here
is the bread board circuit
In this image
I used a white led with proper resistor. Similarly we can design
resistor for our circuits.
In this above
images I have used some other components like led, regulator, Push button. I
will make a separate blog/video to explain they basic operating principle.
In my
breadboard circuit I used a 5 volt regulator to regulate the output voltage to
5 volt which is obtained from 9 volt battery. 5 ohm resistor is not a standard resistor so I
used two 10 ohm resistor in parallel ( In many cases we much use standard
resistors because resistors like 8.2 ohm,69 kilo ohms are possible so we have
to buy approximate standard resistor)
In future I will explain the series and
parallel connection of resistors, capacitor, inductors, power supply batteries
etc.
First you
must learn to how to calculate the resistance of a resistor from the resistor
colour code that information is not available here but my youtube video will
help you to understand this stay cool I will explain everything in my youtube
video.
So friends I
hope my blog was useful keep supporting me so I can make awesome videos/blog
post for you.
What’s
next?
In my next blog I will explain what is a
capacitor, workings, and there applications in practical circuits.
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youtube channel ”ANK LABS”
you can
learn the basic of electronics and there components, labview software, some awesome
electronic project .additionally I will upload some videos some the internships
and implant training which I have attended so far.
