Monday, 22 December 2014

need an amplifier? make it yourself

In my previous post, I have already discussed  on the pin configuration of the ic lm386,
Today I am going to discuss on a simple application of this chip, “simple audio amplifier”
What is an audio amplifier?
Audio amplifier is such a device which takes input signal of lower amplitude, and gives a amplified output whose amplitude may be several hundred times greater than output given,
In this project I am giving the input signal from my mobile phone’s 3.5mm head phone jack,
How to take audio signal from phone’s head phone port?
Do you have any old headphone? Just cut it, you will get 3 or 4 wires there, try to connect them alternatively with a small speakers, for those two wires The speaker sounds , take those two wires,
Components required- lm 386 ic chip
2.capacitor 10 micro farad, 220 micro farad,0.1micro farad
3.resistor 10k
4. 8 ohm speaker
Circuit diagram- 200 gain

simplest audio amplifier

How the circuits works?
The audio signal is applied though the pin 2 and 3,
Between two gain terminal 1 and 8 a capacitor is added, e pin 7 is connected to ground, It works as by-pass, the amplified output is take from the pin 5 and ground.
the circuit i have made

proteus diagram-

Similar models-
“cell phone radiation detector”
Here everything is almost same with the basic audio amplifier, the modifications are
1.  Make a simple coil with any type of wire, connect it’s two terminal with pin 3 and pin 2,
2.   Connect a led instead of the speaker,
How it works?
The little power of the phone signal, induces the coil, the current for the induction acts as input signal, when somebody calls to the mobile placed beside the circuit,the led blinks,

The circuit made by me-  

the real animation 

Thank u for reading, don’t forget to give your valuable comment.

Sunday, 21 December 2014


As we are electrical engineering student, so often we have to deal with high voltage electrical instrument. Here safety is a very important issue.

So, here in this presentation I shall try to give you some ideas on electrical hazards and safety.
FElectrical current is the flow of electrons through a conductor.
A conductor is a material that allows electrons to flow through it.
An insulator resists the flow of electrons.
Resistance opposes electron flow.
Shock – Most common and can cause electrocution or muscle contraction leading to secondary injury which includes falls

Fires – Enough heat or sparks can ignite combustible materials
Explosions – Electrical spark can ignite vapours in the air
Arc Flash - can cause burns ranging from 14,000 degrees f. to 35,000 degrees f
Arc Blast – In a short circuit event copper can expand 67,000 times. The expansion causes a pressure wave. Air also expands adding to the pressure wave.
Effects on human body
More than 3 milliamps (ma): painful shock

More than 10 ma: muscle contraction
More than 20 ma: considered severe shock
More than 30 ma: lung paralysis - usually temporary
More than 50 ma: possible ventricular fibrillation (usually fatal)
100 ma to 4 amps: certain ventricular fibrillation (fatal)

Over 4 amps: heart paralysis; severe burns
How shock occurs
Current travels in closed circuits through conductors (water, metal, the human body).
Shock occurs when the body becomes a part of the circuit.
Current enters at one point & leaves at another.
Main causes of accident-
Drilling and cutting through cables
Using defective tools, cables and equipment
Failure to maintain clearance distance of 10 feet
Failure to guard live parts from accidental worker contact
Unqualified employees working with electricity
Improper installation/use of temporary electrical systems and equipment
By-passing electrical protective devices
Not using GFCI (ground fault circuit interrupters) devices
Missing ground prongs on extension cords

Some safety tips-
Make them grounded
All current carrying metal parts.
All circuits and extension cords.
Portable & semi-portable tools and equipment unless double insulated make them grounded
Use automatic shutting off technology
We can be safer by automatically shutting off the flow of electricity in the event of leakage, overload, or short circuit.  
Ground Fault Circuit Interrupters (GFCI) are circuit protection (or “over current”) devices that protect you, the worker.
Circuit breakers & fuses protect equipment, not you, because they take too much current & too much t.ime to trip
DO not reverse polarity
Make the un-covered wire elevated minimum 10 feet from your head.
Always use insulated wire
Rubber and plastic is put on wires to prevent shock, fires, short circuits and for strain relief.
It is always necessary to check the insulation on equipment and cords before plugging them in.
The first way to safeguard workers from electrically energized wires is through insulation.
Remember, even the smallest defect will allow leakage!
Don’t touch the electrical equipment with wet hand
Keep electric equipment away from children.

Electricity is a bless to modern world, we can not imagine  a day without it , but sometimes it becomes curse to man,  so we have to deal with it vary care fully to keep us safe from electrical hazards, Always follow the safety tips.
Safety first
FFundamental of electricityFundamental of electricityundamental of electricity

Analog v/s digital and the future world

The journey of electrical /electronics engineering was started more than250 years ago,
From that time many innovation has been done by scientists.
At the very beginning scientists were aware only about direct current(DC),
Then alternating current was invented, opening a new age of electrical engineering, using alternating flux, transformer was invented,
Day by day scientist begun to think on a component which has a property of selectivity .  first came vacuum triode, after a very long time research transistors invented,
Then a new era of electronics engineering  opened,
At the beginning there was only analog  electronics,
What is analog electronics?
In analog system both input and output are continuous, like a flow of water with in a pipe,
Suppose you have a pipe, the diameter of the input channel is greater than the diameter of the output channel. Here you connect the pipe with a pump, what would you notice?
You must notice that the speed of the water coming from output channel , is greater than ihe input channel speed, like this process a analog system works.
Day by day, with the help of Boolean algebra and  using transistor and other semiconductor , various logic gates were implemented,
The age of digital electronics started.
How digital system works?
Digital  system works using Boolean algebra, there input and output is not continuous like analog system, it works only using two state
1.   low(0)  (amplitude is lower than defined value)
2.   high(1) ( amplitude is higher than defined value)
suppose , you have some balls, and you are throwing them one by one, one ball in one time, this may be an example of digital or discreet system,

Programmable digital devices-
After the implementation of memory, which can store digital data, then programmable digital devices came, program is stored in this memory, and the device works according to the instructions of the program. There are many programmable devices in the market, like microcontrollers( avr series atmega16,atmega32, and pic series )
Now a days  programmable digital devices are widely used , because any type of work can be done using different program , like an open source hardware.

There are many advantages in digital devices, but one important disadvantage is , it is controlled by a program , any little change in the program can corrupt the total system,
The program can be changed from outside.
This allows hackers to hack the system………………………………

In analog system there is no external control, so it is free from hacking,
Though the digital system has some drawbacks, for its multipurpose functionality , it will be widely used I future,
But some special security purpose, analog system is better………………………………………………………………


Thanks for reading, Don't forget to give your valuable feedback,

“temperature dependent fan Speed control”

Hello, how are you?
Thank you for coming again on
Today I am going to discuss on a very simple but effective and interesting project, that is “temperature dependent  fan Speed control”
Hope you all experienced the fact that, during the end of the summer season, the temperature of the environment   falls significantly, at late of night. Sometimes that becomes the cause of getting cold, if the fan is running still then.
How it would be, if the fan speed decreases with the decrease of temperature?
Yes, in this project we are going to do that…………………
Components required- 1. Any npn transistor
                                            2.temperature sensor ic LM35
3.A SIMPLE 3 VOLT DE MOTOR(you               can find it inside a toy car)
                                            4.  A 5 volt dc source

Circuit diagram- here is a very simple circuit diagram for you
HOW IT WORKS- it’s working principle based on the amplification characteristics of a transistor, a small change in base current causes a greater change in collector current,
The temperature sensor ic LM 35 gives a output ,due to the change of temperature of environment, this pulse is fed to the base of the transistor. And the output collector current runs the motor.

Special note-1. here I have  used simple 3 volt dc motor, if you want to drive a bigger one you must have to interface a relay with the circuit.
 2.the circuit needs some modification, to drive house hold single phase fans,
In my next post I will discuss about the modification.
3.if you want to control the sensitivity of the circuit, you may use a variable resistance between sensor output and transistor base.
Thank you for reading,


Saturday, 20 December 2014

simple method to blink a led or generate a tone

Hello, how are you?
In my previous post, I have discussed on the pin configuration of NE555 timer ic,
Today I am going to apply the astable configuration of 555 ic to blink a led with a defined interval of time,
The astable mode of 555 is a free running oscillator condition, which generates pulses with defined time interval,
We get the pulse output from pin no 3
In this led blinking project, we will use the output pulse to glow the led, NE555 can deliver enough power to drive the led.
Required component list-
1.   One NE555 timer ic
2.   Resistances- 1k, 10k,220ohm
3.   Electrolytic capacitor -10 micro farad
4.   Ceramic capacitor-0.01 micro farad
5.   One led
6.   One 6 volt or 9 volt power supply source
Circuit diagram-

Note- you can change the time delay of blinking by changing  the values of capacitor and resistance,
You can use 220 ohm resistance with the led instead of 1k,
Actually    I have discuss a simple application of astable mode, this mode is often used in electronics to generate continuous pulse, which is used in triggering other digital circuits,
You may generate tones using the pulses, just put a speaker in the place of the LED,
 circuit diagram-

Thank you for reading, keep visiting my blog.