This document provides a project synopsis for a code lock switch circuit designed by students at the Shri Ram Murti Smarak College of Engineering and Technology in Bareilly, India. The circuit uses a 4-digit numeric code that can be changed to unlock a relay and light an LED. It includes a reset feature to prevent random pressing of numbers if an incorrect code is entered. The circuit diagram, components list, description of how it works, and conclusions about replacing a conventional key switch with a code lock are described over the course of the synopsis.

1. SHRI RAM MURTI SMARAK
COLLEGE OF ENGG. AND TECH. BAREILLY
PROJECT SYNOPSIS ON
CODE LOCK SWITCH
Submitted to: Submitted By:
Mr. Deshraj Dharmveer Singh
Meenakshi Maurya
Project Guide: Monika Karwa
Mr. Mahendra Vivek Yadav
[ELECTRONICS AND COMMUNICATION ENGG.]
[BATCH-2011]

3. INTRODUCTION
For in this circuit uses a four numeric code number and this code number can be changed
up to one thousand numbers.
The case with other people to know our original code. They code can be changed easily.
The circuit is designed to have the reset system, immediately enter the wrong code,so can
prevent pressing a random numeric code. Because in this circuit the switches are set to the
ten numbers, be the code switch 4 pcs. and be reset switches 6 pcs.
The advantages of having a system reset, suppose we set the code number is 6583, If
people do not know the code, they will press random from 0 to 9, It will be has one correct
number is 6. But the press randomly in the second round. Not that he would press any
number that not the 5, The circuit will reset a number 6 which was originally to be
released.
So he will enter a code be correctly, just the first digit only. However, if as without the reset
system. Even those who do not know the code, it can be opened is the random pressing in a
fourth round only.
When he hit 0-9 from the first round he will correctly hit to the No.6. then he hit the second
round will correctly is one no.5 as well. When the full four rounds, it would has a four code
so the circuit is working. This difference is quite obvious. When talking about the
advantages – and disadvantages, then to look at the circuit and how it works really well.

4. CIRCUIT DIAGRAM
FIG: Circuit Diagram of Code Lock Switch

5. COMPONENTS
S.No. Components Rating Quantity
1. IC 74HC4017 or CD4017 1
2. Relay 9V 1
3. Resistors
R1,R2
R3
R4
100kΩ,1/4 W
10kΩ,1/4 W
1kΩ,1/4 W
4
4. Transistor(Q1) 2SC458 or 2SC1815 or
2N3904
45V, 100mA NPN
1
5. Capacitor 100μF,25V 1
6. LED 3mm 1
7 Switches Tactile ON OFF Single
Pole, Single Throw Round
Button
10

6. CIRCUIT DISCRIPTION
This circuit uses an 74HC4017 or CD4017 IC Number that is DECODE Counter model. It
serves to change the code. In normal conditions, when we provide a power supply to this
circuit be has a positive voltage output at pin 3 of IC1. When you press the switch A-S1, The
positive voltage from pin 3 to pass switch to the pin 14 of IC1, which is an input pin.
Then when IC1 has the input is positive voltage, it will move the output from pin 3 to pin 2.
so the next switch that must to press to be the switch B – S2 for has the positive voltage at
the input of IC1 in next step. As you can see, if we do not press the switch B, it will not
change any of the IC.
And if we push a switch wrong away, to press switch that be one of six options on the left
hand side of this circuit. It is the positive voltage pass the switch to the input pin 15 that be
reset of IC1, When does it matter the pin 15 is given the positive voltage, IC1 will change
the output to at pin 3, so it is resetting switch A to restart new again.
If you press the correct always from ABC to D, IC will move output to Pin 10. Which is pin
be connected through a diode, and R-10K to pin B of the Q1-2N3904, making the Q1 is
conduct, Ry1-relays and LED’s are working together to relay, the light to this circuit work,
then let us know. For the five diode that connected to the out of IC1 You are prevented
Output is provided to prevent is disturbanced in the code that the two codes are the same
as 5385 code.

7. CONCLUSION
This key code switch circuit is a type of electronic circuit that is created to replace
conventional normal key switch. Without inserts a keys.
But you can press the number code instead of unlock keys. We do not have to carry a load
key and do not worry about your keys are lost. We just must remember to commit to a code
only.