project proposal3
Post on 02-Apr-2015
171 Views
Preview:
TRANSCRIPT
MINDANAO UNIVERSITY OF SCIENCE AND TECHNOLOGY
College of Engineering and Architecture
DOOR KNOB ALARM
In Partial Fulfillment as a Requirement for ECE 21 (Electronics II)
Submitted By:
JOHANN JUDE G. ALBIA
JOJO I. EROJO
Submitted To:
LLOYD JHON B. ESTAMPA, MSEcE
February 2011
I. PROJECT BACKGROUND AND DESCRIPTION
In the year 2009 crime rate about robbery with homicide had increase. The PNP said that the
total crime volume in 2009 was recorded at 101,798 incidents with 61.26 % of these index crimes like robbery,
murder and other offenses against persons, and 38.74 % non-index offenses, or crimes against property. The PNP
said that crime rate in 2009 indicated a 63.79% increase, as the total crime volume in 2008 was only 62,148. In
line with this we as a students aim to help society through awareness of security precautions. For this we
have come up to introduce doorknob alarm.
The first documented invention of the doorknob appears in U.S. patent entries for the year 1878
when a patent for improvements on a door-closing device and Osbourn Dorsey invented it. Doorknobs
have been used around the world for centuries, and were first manufactured in the United States in the
mid nineteenth century. Doorknobs have been made of many materials including wood, glass, ceramic,
plastic and different types of metal. Brass is one of the most popular materials because of its excellent in
resistance to rust. The average doorknob is 2.25m in diameter. The basic components of doorknob are
the knob rose, shank, spindle, and knob-top. (See figure 1.1).
Figure 1.1 Basic components of doorknob
The door is an integral part of any door handle system. As far as main entry security goes the
doors role is to keep out undesirable. For interior doors, the door handle acts as a latch to keep the door
closed for privacy. Doorknob locks are an important part of any home security system. It is also true that
human by nature needs to protect themselves and this is the main objective of creating this research.
Doorknob Alarm does not just a closing device it is also helps home owner if the lock has broken. This
prevents a thief from being able to open the door by breaking the knob because of its alarming noise.
Many companies offer simple alarm devices for personal use in bedrooms or hotel rooms. A
metal chain attached to a box holding the electronics is placed around the inside doorknob of a wood
door. Anyone grabbing the knob from the outside is detected by the electrical capacitance change that
occurs from the human hand contact between the knob and the box. Almost all of the commercial
devices sold use a more expensive and power consuming radio frequency circuit approach to detect the
capacitance change. But, a very inexpensive and micro power technique can also work. This electronic
circuit schematic should dramatically reduce the cost of the device and the power drain is so small that it
will operate for many years from one set of AA or AAA batteries.
This doorknob security alarm turns an ordinary doorknob into a burglar alarm. Any thief will
first try your doors to see if they are unlocked. If a burglar touches your outside doorknob (must be a
wooden or fiberglass door -- will not work on metal doors) this device will instantly emit a loud alarm to
scare him away and alert you to the attempted entry. Unlike other alarms, the burglar will be stopped
before he enters your home or hotel room or office. Even if he is wearing gloves, the alarm will sound as
soon as the outside doorknob is touched.
This circuit emits a beep when someone touches the door-handle from the outside. The alarm
will sound until the circuit will be switched-off. The entire circuit is enclosed in a small plastic or
wooden box and should be hanged-up to the door-knob by means of a thick wire hook protruding from
the top of the case. A wide-range sensitivity control allows the use of the Door Alarm over a wide
variety of door types, handles and locks. The device has proven reliable even when part of the lock
comes in contact with the wall (bricks, stones, reinforced concrete), but does not work with all-metal
doors.
Let this paper be a trigger to all prospect readers to be conscious of two things: Safe and Secure.
II. TRANSISTORS UTILIZED IN THE PROJECT
A transistor is a semiconductor device used to amplify and switch electronic signals. It is made
of a solid piece of semiconductor material, with at least three terminals for connection to an external
circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing
through another pair of terminals. Because the controlled (output) power can be much more than the
controlling (input) power, the transistor provides amplification of a signal. Today, some transistors are
packaged individually, but many more are found embedded in integrated circuits.
The transistor is the fundamental building block of modern electronic devices, and is everywhere
in modern electronic systems. Following its release in the early 1950s the transistor revolutionized the
field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers,
amongst other things.
The transistor used in this project is ZVNL110A MOSFET transistor. But this transistor is not
available in our city, so we will use a BS170 (See figure 2.1) transistor which is a good substitute to
ZVNL110A.
Figure 2.1 BS 170 Transistor
This BS170 is an N-channel, enhancement-mode MOSFET used for small-signal switching
applications. Packaged in a TO92 enclosure, the BS170 is a Vds<60 V (Vgs<20V) device capable of
switching in the 200-500 mA range with a minimum on-resistance of 1.2 Ω. The BS170 is nearly
identical to the 2N7000 (see figure 2.2), except that the leads are arranged differently.
Since it is also identical with 2N7000 (See figure 2.2), we will just use either of them yet for
sure; they both work perfectly on the project.
Figure 2.2 2N7000 Transistor
The 2N7000 is an N-channel, enhancement-mode MOSFET used for small-signal switching
applications. Packaged in a TO92 enclosure, the 2N7000 is a 60 V device capable of switching in the
200-350 mA range with an on-resistance of 0.3-5 Ω. The 2N7000 is nearly identical to the BS170,
except that the leads are arranged differently.
The main use of the 2N7000 is as a switch for low voltages and currents. In switching circuits, the
2N7000 can be used much like a bipolar junction transistor, but has some advantages:
low threshold voltage means no gate bias required
high input impedance of the insulated gate means almost no gate current is required
consequently no current-limiting resistor is required in the gate input
The main disadvantages of the 2N7000 over a bipolar transistor in switching are the following:
susceptibility to cumulative damage from static discharge prior to installation
circuits with external gate exposure require a protection gate resistor or other static discharge
protection
Non-zero ohmic response when driven to saturation, as compared to a constant junction voltage
drop in a bipolar junction transistor
The circuit symbol for the 2N7000 generally does not show the internal diode formed by the
substrate connection source to drain.
III. CIRCUIT FLOW EXPLANATION
Figure 3.1 The schematic diagram
3 sections: An Oscillator, The Sensor, & The Alarm
Notes:
This project uses a flip-flop as you can see at the oscillator and sensor stages. It is a circuit that
has two stable states and can be used to store state information. The circuit can be made to change state
by signals applied to one or more control inputs and will have one or two outputs.
The flip-flop has four inputs. These are:
D - DATA input: It is connected either to a LOW voltage, logic 0, or to a HIGH voltage, logic 1.
CLK or CK - CLOCK input: It responds to sudden changes in voltage, but not to slow changes
or to steady logic levels. The CLOCK input of the 4013B D-type bistable is rising-edge
triggered, meaning that it responds only to a sudden change from LOW to HIGH.
S - SET input: The SET input is normally held LOW. When it is pulsed HIGH, the outputs of the
bistable are forced immediately to the SET state, , .
R - RESET input: The RESET input is normally held LOW. When it is pulsed HIGH, the
outputs of the bistable are forced immediately to the RESET state, ,
Q and Q-bar – are the reactance outputs.
The flip-flop used in the circuit is a 4013B Flip-flop:
General Description:
The 4013B flip-flop is a monolithic complementary MOS (CMOS) integrated circuit constructed
with N- and P-channel enhancement mode transistors. Each flip-flop has independent data, set, reset,
and clock inputs and “Q” and “Q” outputs. These devices can be used for shift register applications, and
by connecting “Q” output to the data input, for counter and toggle applications. The logic level present
at the “D” input is transferred to the Q output during the positive-going transition of the clock pulse.
Setting or resetting is independent of the clock and is accomplished by a high level on the set or reset
line respectively.
Features:
Wide supply voltage range: 3.0V to 15V
High noise immunity: 0.45 VDD (typ.)
Low power TTL: fan out of 2 driving 74L
compatibility: or 1 driving 74LS
Applications
• Automotive • Data terminals • Instrumentation • Medical electronics • Alarm system
• Industrial electronics • Remote metering • Computers
To explain the circuit flow of this Project we will discuss each of its sections namely; the
oscillator, the sensor and the alarm.
The oscillator
The first section of the circuit is an oscillator based on a flip-flop. The flip-flop used in the
circuit is a 4013B flip-flop (see notes). CLK (node 3) and D (node5) are both grounded while R (node
4) is tied high. Hence, the output Q (node 1) will only be high if S (node 6) is high. When the output is
low, the transistor Q1 is cutoff. This allows S to be charged with a delay relating to the system of
impedances R1, R2, R3, and C3. Once the voltage at node 6 triggers S, the output changes to high and
Q1 is opened. Node 6 then discharges out through the capacitor. Once node 6 is low enough, S is no
longer triggered and the output is automatically reset (because R is tied high) to low and the process is
repeated.
Figure 3.2 shows node 6 charging and discharging as the blue trace. The yellow trace is the
output Q at node 1. You can see that the output turns high when node 6 reaches the switching threshold
of the flip-flop (about 1.8 volts). Right afterwards it spikes up due to feedback through C2, but quickly
starts discharging. The oscillator switches off when node 6 returns below the 1.8volt switching voltage.
Feedback through C2 draws node 6 to ground before the process repeats itself.
Figue 3.2
Source: http://photos.ruschmann.net/index.php?album=Electronics-Projects/Doorknob-Sensor&image=charge.png
Legend (traces):
---------- : Charging and discharging at S (node 6)
---------- : Output Q (node 1)
In order to change the period of oscillation, adjust the value at C3. If you would like to make the
pulses longer, adjust C2. The circuit works well right where it is at, though. Finally when Q1 opened the
next stage (the sensor) takes place.
The Sensor
The second section of the circuit is the sensor where the wire loop on the doorknob is involved.
This wire loop is one of the significant components of the project that is directly attached to the
doorknob. This will be the way that connects to the circuit if someone touches the doorknob outside.
After the oscillator section, the output at Q1 is divided down into two paths. First path is
connected in series with R4 (200 KΩ sensitivity potentiometer). This potentiometer can be adjusted to
lower or increase the output alarm as the circuit determines or detects that the doorknob is being
touched. The path to node 11 is the Clock input of the flip-flop, and the path to D (node 9) determines if
someone’s touches the doorknob or not.
Figure 3.3
Source: http://photos.ruschmann.net/index.php?album=Electronics-Projects/Doorknob-Sensor&image=touched.png
In figure 3.3, D (node 9) high than the clock. Hence, the flip-flop stays high when the leading
clock edge triggers it to lock. When the doorknob is touched, your body absorbs some of the charge and
D (node 9) charges slower. When the clock edge rises, D (node 9) is not high yet and low value is
locked into the flip-flop. Datas or informations from D (node 9) are now transferred to the output Q-bar.
The alarm
The last section of the circuit is the alarm; this is where we finally observe the final output which
is a sound alarm. We use an audible buzzer in order to relay the alarm. This is also my intent for the
circuit, but we use a LED in the photos because we cannot see sound. It is attached to the inverting
output of the second flip-flop Q-bar because it is high when the alarm is triggered.
The function of the alarm section is simple; it simply waits for the output Q-bar at the sensor
section to be delivered. It is only delivered if someone touches the doorknob and the alarm section will
now workout. Q2 is involved in the process. To end this circuit, the buzzer or LED (temporarily used) is
finally triggered to relay the alarm.
In addition, you can have a switch in order to turn the project on/off.
IV. PICTURES OF THE PROJECT
We don’t have actual photos yet on our project, we only have photos from the internet. The
circuit is temporarily and tested at the breadboard.
Fidure 4.1 Circuit layout using breadboard
source: http://photos.ruschmann.net/index.php?album=Electronics-Projects/Doorknob-Sensor&image=circuit.jpg
Figure 4.2 Circuit layout using breadboard
Source : http://photos.ruschmann.net/index.php?album=Electronics-Projects/Doorknob-Sensor&image=alarm3.jpg
In this photo, you could see on how the circuit is placed on the breadboard. A 3V DC voltage is
supplied by a AA cells battery. Resistors, capacitors, transistors, flip-flops, LED and wires are shown.
Figure 4.3 Installing the project
Source: http://photos.ruschmann.net/index.php?album=Electronics-Projects/Doorknob-Sensor&image=connected.jpg
The proper way of installing the project is shown in the figure 4.3. The wire is attached and
looped at the inside part of the doorknob. This wire would be sensitive and determines precisely if a
sudden movement or vibration is detected, when someone touches the doorknob outside.
V. BILL OF MATERIALS
QUANTITY MATERIAL COST
1 R1 4.7M Ω 1/4W resistor P0.35
1 R2 12K Ω 1/4W resistor P0.35
1 R3 2.2M Ω 1/4W resistor P0.35
1 R4 200K Ω (sensitivity adj.) potentiometer P8.50
1 R5 330K Ω 1/4W resistor P0.35
1 R6 470K Ω 1/4W resistor P0.35
1 R7 10K Ω 1/4W resistor P0.35
1 C1 47µ F P3.00
1 C2 0.0047 F P0.75
1 C3 0.022 µ F P0.75
1 C4 15p F P0.75
1 C5 12p F P0.75
1 C6 470p F P0.75
2 Q BS170 or 2N7000 P3.00
2 Flip-flop 4013B P28.00
2 AA Cells P15.00
1 Buzzer Star MMB-01 P45.00
1 PCB(3”x4”) P12
1 Battery Holder P10
1 box P30
TOTAL COST P160.35
VI. REFERENCES
http://www.discovercircuits.com/DJ-Circuits/dooralm2.htm
http://www.discovercircuits.com/H-Corner/doorknob.htm
http://www.datasheetcatalog.org/datasheet/zetexsemiconductors/zvnl110a.pdf
http://superpositioned.com/2006/04/25/doorknob-touch-alarm/
http://superpositioned.com/files/dooralm2.pdf
http://www.electronics-project-design.com/
top related