Published on 2:20 AM by Shyamal on May 20, 2013 | 0 Comment
LDR is a special type of resistance whose value depends
on the brightness of the light which is falling on it.
It has resistance of about 1 mega ohm when in total darkness,
but a resistance of only about 5k ohms when brightness
illuminated. It responds to a large part of light spectrum.
When light falls on the LDR then its resistance decreases which
results in increase of the voltage at pin 2 of the IC 555...
Published on 1:40 AM by Shyamal on May 19, 2013 | 0 Comment
The frequency oscillator is built with 741 Op-amp and related components.
The carrier signal frequency and its amplitude can be varied using variable
resistor accordance with VR1 and VR2 respectively. C1 and C2 are the main
components to generate the carrier frequency.
Another part of the circuit is an audio amplifier circuit.
The audio amplifier is built with 741 Op-amp and related components...
Published on 3:10 PM by Shyamal on May 18, 2013 | 0 Comment
Then in pin 2 if the voltage is less than one third of Vcc,
a trigger pulse is active.The pulse signal is fed to clock pin 4 of
counter IC 74109. Pin 8 of 74109 IC is grounded, pin 16 is connected to
Vcc and pin 3 is grounded.
The relay is connected through a fan and a regulator. It gets connected
to live terminal of AC mains via normally opened (N/O) contact when the relay
energizes. If we want to operate a DC 12 volt relay...
Published on 12:20 PM by Shyamal on May 17, 2013 | 0 Comment
purpose of this circuit is to secure your room in night. You need not
any security guard. When any unwanted person wants to enter your room in night
then this circuit raised alarm. On the other benefit,
There are five separates parts in this circuit – regulated power supply,
relay driver, door switching...
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