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.