1. ANALOGELECTRONICSCIRCUIT
TOPIC-SOUNDDETECTOR
BY
VEDAVYASP.B
2013-2014

2. Title:-To design and analyze the sound detector circuit.
Objective: - To analyze the sound detection using quad op-amp
and getting the output across the led.
Components required:-
Components Specification Quantity
Quad op-amp LM324 01
Microphone - 01
Bread board - 01
Capacitors 0.1uF,10uF 01 each
Resistors 1k,10k,100ohm 01
Resistors 100k 04
Connecting wires - -
Power supply 5v dc 01

3. Experimental setup:-
Theory:-
Students often want to use ‘sound’ as an input within electronic
projects. Unfortunately sound is not as easy to use as light and
temperature, as there is not an instant ‘single component’
solution, as is the case with, for example, an LDR for light or a
thermistor for temperature. A low-cost Electret microphone (e.g.
Rapid 35-0192) will provide an output of around 1mV rms from
normal speech at a distance of around 60 cm. So you can expect
signal levels from the microphone of around 1 - 3 mV. An electret
microphone is a special type of Field Effect Transistor (FET), which

4. converts vibrations (from sound or physical contact) into an
electric signal, which is then amplified internally by the FET, and
must be connected the correct way around - the 0V (negative) leg
can be identified as it is connected to the external metal can by a
visible tag.
Quad op-amplifier used in this experiment is LM324 which plays
important role in signal conversion. All the standard capacitors
and resistors are used in this experiment. Input supply of 5v is
given and output gets across LED.
Working principle:-
LED glows whenever I make sound and turn off when my audio
level becomes zero.
Microphone converts audio signals into electrical signals these are
basically A C.
High pass filter is built putting capacitor and a resister. Thereby
only those signals which converted to electrical signal passes
through the op-amp.
I/p from microphone have 0.02v hence op-amp act as a amplifier
so its gain is 100 then its o/p is of 2v.
Datasheet:

5. DESCRIPTION
The LM324series consists of four independent High-gain, internally
frequency-compensated operational amplifiers. Designed specifically to
operate from a single power supply over aWide range of voltages
UNIQUE FEATURES
In the linear mode, the input common-mode voltage range includes
Ground and the output voltage can also swing to ground, even
Though operated from only a single power supply voltage.
The unity gain crossover frequency and the input bias current are
Temperature-compensated.
Discussion of result and Conclusion: - After analysis of the sound
detector we can conclude that quad op-amp amplifies the
noiseandconverts in to electrical signal which in turn can be detected
across frequency modulation transmitter.