This is a brief description of our project 8 Bit Digital code Lock Intercom System. It contains the functional and circuit block diagram. It has the circuit layout and also the hardware model.

1. TECHNICAL PAPER
PRESENTATION
ON
8 BIT
DIGITAL CODE
LOCK
INTERCOM
SYSTEM
BY
SAGNIK
JANA
E.C.E, 4th

2. ABSTRACT
 Intercom system : It primarily comprises of a
microphone, a speaker and an amplifier.
The locking circuit provides an 8-bit digital
code. As soon as the code matches the
intercom system becomes operational.
The Intercom system is of a great help for
intra building communication.

3. OVERVIEW
The code lock circuit primarily uses four DIP
switches and two magnitude comparators
(7485) which drives the relay to the console
when code matches
The intercom console broadly consists of an
audio power amplifier (LM386), a
microphone and a speaker.
 It is important that there is no acoustical

4. FUNCTIONAL BLOCK
DIAGRAM

5. CIRCUIT BLOCK DIAGRAM

6. OPERATIONAL FLOW CHART
Dc power supply
 The 230 volts ac supply is fed to the step down
transformer which provides a 16 volts ac at its
output.
8-bit lock code
 The password is first set using a preset dip switch
of 8-bit length & magnitude comparator energizes a
relay which switches on the intercom system.
Intercom system
 The blocking capacitors only allows ac component
& filters the noise.

7. CIRCUIT LAYOUT

8. HARDWARE MODEL

9. BIBLIOGRAPHY
 http://www.al ldatasheet.com/datasheet -
pdf/pdf/8074/NSC/7485.html
 http://www. researchcel l.com/general/7809-pin-and-circui t -
diagram/.html
 http://www.engineersgarage.com/elect ronic-components/7805-
vol tage- regulator - ic.html
 http://en.wikipedia.org/wiki/BC548.html
 http://www.engineersgarage.com/elect ronic-components/
t ransistor-bc547-datasheet.html
 http://www.datasheetarchive.com/IN-4001-datasheet .html
 http://www. t i .com/product/lm386.html