An electromechanical buzzer works by using an electric current to interrupt its own circuit, causing contacts to vibrate and produce a buzzing sound. Piezoelectric buzzers use a piezoelectric element that produces a sound when driven by an oscillating electronic circuit. Buzzers are used in a variety of applications like alarm devices, game shows, and appliances to indicate input or provide an audible signal.

1. Buzzer
.
A buzzer or beeper is an audio signalling device,[1] which may be mechanical,
electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarm devices,
timers and confirmation of user input such as a mouse click or keystroke.
Example of an electronic buzzer (indicating "wrong" or "fail")
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Contents
1 Mechanical
2 Electromechanical
3 Piezoelectric
4 Uses
5 See also
6 References
Mechanical
A joy buzzer is an example of a purely mechanical buzzer.
Electromechanical
Early devices were based on an electromechanical system identical to an electric bell without the
metal gong. Similarly, a relay may be connected to interrupt its own actuating current, causing
the contacts to buzz. Often these units were anchored to a wall or ceiling to use it as a sounding
board. The word "buzzer" comes from the rasping noise that electromechanical buzzers made.

2. Piezoelectric
Piezoelectric disk beeper
A piezoelectric element may be driven by an oscillating electronic circuit or other audio signal
source, driven with a piezoelectric audio amplifier. Sounds commonly used to indicate that a
button has been pressed are a click, a ring or a beep.
Uses
Annunciator panels
Electronic metronomes
Game shows
Microwave ovens and other household appliances
Sporting events such as basketball games
Electrical alarms
See also
Alarm clock
Alarm management
Klaxon
Vibrator (mechanical)
Electric bell
CRYSTAL
crystal or crystalline solid is a solid material whose constituent atoms, molecules, or ions are
arranged in an ordered pattern extending in all three spatial dimensions. In addition to their
microscopic structure, large crystals are usually identifiable by their macroscopic geometrical
shape, consisting of flat faces with specific, characteristic orientations.[citation needed]

3. The scientific study of crystals and crystal formation is known as crystallography. The process of
crystal formation via mechanisms of crystal growth is called crystallization or solidification. The
word crystal is derived from the Ancient Greek word κρύσταλλος (krustallos), meaning both
“ice” and “rock crystal”,[1] from κρύος (kruos), "icy cold, frost".[2][3]
Common crystals include snow flakes, diamonds, and table salt; however, most common
inorganic solids are polycrystals. Crystals are often symmetrically intergrown to form crystal
twins.
TSOP Sensor
TSOP is the standard IR remote control receiver series, supporting all major transmission codes. This is
capable of receiving infrared radiation modulated at 38 kHz. IR sensors we have seen up to now working
just for few short distance up to 6 cm. TSOP is sensitive to a specific frequency so its range is better
contrast with ordinary photo diode. We can alter it up to 15 cm.
TSOP acts like as a receiver. It has three pins GND, Vs and OUT. GND is connected to common ground, Vs
is connected to +5volts and OUT is connected to output pin. TSOP sensor has an inbuilt control circuit
for amplifying the coded pulses from the IR transmitter. These are commonly used in TV remote
receivers. As I said above TSOP sensors sense only a particular frequency.
Features:
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Photo detector and preamplifier in one package.
Internal filter for PCM frequency.
Improved shielding against electrical field disturbance.
TTL and CMOS compatibility.
Output active low.
Low power consumption.
High immunity against ambient light.
Continuous data transmission possible.
Specifications:
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Supply Voltage is -0.3-6.0 V.
Supply Current is 5 mA.
Output Voltage is -0.3-6.0 V.
Output Current is 5 mA.
Storage Temperature Range is -25-+85 °C.
Operating Temperature Range is -25-+85°C.

4. The testing of TSOP is very simple. These are commonly used in TV remote receivers. TSOP consists of a
PIN diode and pre-amplifier internally. Connect TSOP sensor as shown in circuit. A LED is connected
through a resistance from the supply to output.
And then when we press the button of T.V. Remote control in front of the TSOP sensor, if LED starts
blinking then our TSOP sensor and its connection is correct. The point when the output of TSOP is low
i.e. at the time it appropriates IR signal from a source, with a centre frequency of 38 kHz, its output goes
low.
TSOP sensor is used in our daily use TV, VCD, music system's remote control. Where IR rays are
transmitted by pushing a button on remote which are received by TSOP receiver inside the equipment.
TSOP Sensor Based Projects
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Optimum Energy Management System
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Object Counter with 7 Segment Display
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TV Remote Operated Domestic Appliances Control
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Using TV Remote as a Cordless Mouse for the Computer