Prepared by:
&
Supervisor: Dr. Samer Mayaleh.
 What is Master Lock?

It’s A kind of Locks that you have to select a set of digits –combination- in
order to open it.

However , people sometimes forget their combinations. then need to buy a
new one.

It's very important for a person to know his old combination lock.

Our lock is a Master lock 1500D.

This lock the most commonly used brand.

Have 3 numbers every number consists of 2 digits at most .
a 40 *40* 40=64,000 possible combinations.

The 1st & 3rd number you have to turn to right direction, the 2nd to the left.
with
Description of the project:
The main goal of our project is to create a device that:
 Open
the Lock when the person insert the correct
combination.

can open a combination lock with an unknown
combination !(auto unlock)
 Then
report the correct combination to the owner !
To open the Lock.
For the normal person to try the all possible combinations
(40×40×40 = 64,000)
It would take
11 days+2hour+40minute = 16,000 minutes !!!..
With the new algorithm developed in this project to Crack the lock
resulted in reducing the number of the possible combinations to
100 possible combinations.
To try these 100 combination it takes
ONLY 30 minutes !.
In our project these 100 possible combinations using
PIC16F877 microcontroller takes less than 7 minutes at worst
Case.
Cracking the lock.
Finding the
3rd number
by finding the
Gates
12 gate will
be found
5 of the gate will
be whole number
7 of the gates will
be half number
The last digit of one of
whole number will be
different from the rest
This number is the
3rd number of the
combination
3rd
Combination of
the Lock
1.5
4.5
8
12
14.5
18
21.5
24.5
28
31.5
34.5
38
3rd number found
Take this remainder
Divided by 4
Take the remainder
This is the first
possibility of the
first number
To find the other add
4 to this number until
you reach the highest
number (39)
If it is 0 or 1 add 2 to it if
it is 2 or 3 subtract 2
from it
12 % 4 = 0
Then add 4 to this
number until you reach
the highest number (39)
2,6,10,14,18,22,26,30,34,
38
Now, We have 10X10 = 100 possible
combinations
0,4,8,12,16,20,24,28,32,36
Block diagram:
Hardware
Stepper Motor
Photo
sensors
Stepper
Motor Driver
Arm
Fly Wheel
latching
solenoid
MASTER
Lock
H-Bridge
Keypad
LCD
Circuit Diagram:
• PIC Port:
Input Output Unit:
Keypad:
It is the input of the opener .
To open a known combination for
lock You have to insert the 1st num.
followed by # and the 2nd & 3rd .
In auto opening you have just to
insert #.
LCD:
It’s the output of the opener.
it shows the unknown combination after the process
is done.
Driver Units:
a. Stepper Motor
We use 1.8˚ stepper Motor.
We choose it as we do not need to put a negative voltage
across it to reverse the direction.
The motor speed is not controlled by the voltage across the
thermals. It is controlled by the frequency of voltage pulses.
A stepper motor would be the most effective, because of its
precision at turning certain distances.
Stepper Motor Driver :
1- motor step angle
1.8o.
2- can turn the
motor in .9o
increments.
This R
determines the
output current
to the S.M
3- we need 360o
/(40*2)= 4.5o.
4- 4.5o /.9o = 5 half
stepper motor steps
to turn 1 half
number on the lock.
Latching Solenoid:
Its DC Latching solenoid.
We test the amount of force needed to open the latch of the lock it
was 11 Newtons ,this force is applied by our solenoid.
It has 14.4 ohm internal Resistance .
The solenoid ratings 12Volts and 0.84 Amperes.
Solenoid Driver( H-bridge):
Pin 0
Pin1
Low
Low
Low
High
unlatch
High
Low
pull
High
High
unaccepted
In forward :
Is=0.74 A
Vs=10.8 V
output
---------------
Feedback Units
Fly Wheel:
Half Number divisions
40 black and 40 white
Whole Number divisions
20 black and 20 white
The black mark is
aligned with zero on
the lock
Arm:
The arm is the connecting piece between the stepper motor and
the lock dial.
it be as straight as possible and that it grips the lock dial as
firmly as possible.
It must be light in weight so we made it from aluminum bar.
And we try to be empty inside as possible to reduce its weight.
Reflective Photo Sensors (OPB742):
They are 3 photo Sensors.
2 are attached to the top of the fly Wheel , and the 3rd at
the Bottom of the fly Wheel.
Infrared led
photo sensitive BJT
2Holes
And the test Result as follows:
 Vmax = 4.85 volt.
Imax = 4.85/100K = 48.5 µA
(White Surface).
 Vmin = 1.4 volt.
Imin = 1.4/100K = 14 µA.
(Black Surface).
Software
Combination Lock Opener Simplified State Diagram
Feedback
How PIC Know the current Number?
The counter is initialized when photo sensor in the bottom
reads black.
In auto lock we are concerned to determine half numbers .
 Photo sensor in the outer radius of the flywheel counts the
number of black divisions it passed then it decide the number.
And this is done along one total rotation of the dial. after this
process we will have 12 readings(all the Gates).
The inner radius work the same as outer but it work after
cracking to open the lock after it determines the correct
combination .
Problem we Faced:
It was so hard to find stepper motor with such a small degree .
Solution:
We found it finally in microprocessor lab.
Solenoids existed in market having the applications that need a
very little force –like opening video players.
Solution :
After suffering we found one .
There was current that follows toward stepper motor driver
which destroy the first IC .
Solution:
We add a led and resistor in series to the pins of stepper motor
driver that connected with the S.M coils.
Recommendation:
The machine that we are
designed Should not be used for
any unlawful
purpose .
It is very good for an old
combination lock that you forgot
the combination to.
We shall take no responsibility
for anything do from this
machine
Cost Analysis:
And Now we
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