16-08-2011, 09:56 AM
Presented By
Rupesh singh
P.Swaraj Kumar
P. Srinivas
P.Swaraj Kumar
P. Srinivas
[attachment=15291]
SECRET BELL
Abstract
This circuit helps to identify the members of your family. It is basically switch less musical bell that activates with a single puff of breath.
Circuit diagram
Circuit description
The front end of the circuit is a condenser mic amplifier with fixed sensitivity Transistor T1 amplifies the signal received from the condenser mic through capacitor C1.
A zener diode maintains the power for IC2 at a safer level of 3 volts.
Circuit components
TRANSFORMER
DIODE
CAPACITOR
RESISTOR
BC 548&BC 549 TRANSISTOR
BATTERY
IC-7809 REGULATOR
IC-7805 REGULATOR
TOGGLE SWITCH
Condenser Microphones
Condenser means capacitor, an electronic component which stores energy in the form of an electrostatic field. The term condenser is actually obsolete but has stuck as the name for this type of microphone, which uses a capacitor to convert acoustical energy into electrical energy.
Condensers also tend to be more sensitive and responsive than dynamics, making them well-suited to capturing subtle nuances in a sound. They are not ideal for high-volume work, as their sensitivity makes them prone to distort.
How Condenser Microphones Work
A capacitor has two plates with a voltage between them. In the condenser mic, one of these plates is made of very light material and acts as the diaphragm. The diaphragm vibrates when struck by sound waves, changing the distance between the two plates and therefore changing the capacitance. Specifically, when the plates are closer together, capacitance increases and a charge current occurs. When the plates are further apart, capacitance decreases and a discharge current occurs.
UTC UM66
The UTC UM66TXXL series are CMOS LSI designed for
using in door bell, telephone and toy application.
It is an on-chip ROM programmed for musical
performance.
Produced by CMOS technology, the device results in very
Low Power consumption.
FEATURES:
64-Note Rom memory
1.5V ~ 4.5V power supply and low power Consumption
Dynamic speaker can be driven with external NPN transistor
OSC resistor hold mode
Power on reset: melody begins from the first note
Built in level hold mode
