Download Speed Checker for Highways

1
INDEX
S. NO.
PAGE NO.
CONTENT
1.
Introduction
2.
Circuit diagram
3.
Circuit diagram description
4.
Components list
5.
Construction and working
6.
Component description
8.
PCB fabrication
9.
Application
10.
Conclusion
11.
references
2
INTRODUCTION
While driving on highways, motorists should not exceed the maximum
speed limit
permitted for their vehicle. However, accidents keep
occurring due to speed violations since the drivers tend to ignore their
speedometers. This speed checker will come handy for the highway
traffic police as it will not only provide a digital display in accordance
with a vehicle’s speed but also sound an alarm if the vehicle exceeds the
permissible speed for the highway.
The system basically comprises two laser transmitter-LDR
sensor pairs, which are installed on the highway 100 metres apart, with
the transmitter and the LDR sensor of each pair on the opposite sides of
the road. The installation of lasers and
LDRs is shown . The s ystem displays the time taken by the vehicle in
crossing this 100m distance from one pair to the other with a resolution
of 0.01 second, from which the speed of the vehicle can be calculated as
follows:As per the above equation, for a
Speed (kmph) =
Distance
Time
3
0.1 km
(Reading×0.01)/3600 =
or,
Reading (on display) =
Speed
36000
4
speed of 40 kmph the display will read 900 (or 9 seconds), and for a
speed of 60 kmph the display will read 600 (or 6 seconds).
Note that the LSB of the display equals 0.01 second and each succeeding
digit is ten times the preceding digit. You can similarly calculate the
other readings (or time).
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Circuit diagram
6
7
Circuit description
Circuit description shows the circuit of the speed checker. It has been
designed assuming that the maximum permissible speed
for highways is either 40 kmph or 60 kmph as per the traffic rule.
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The circuit is built around five NE555 timer ICs (IC1 through IC5), four
CD4026 counter ICs (IC6 through
IC9) and four 7-segment displays (DIS1 through DIS4). IC1 through IC3
function as monostables, with IC1 serving as count-start mono, IC2 as
count-stop mono and IC3 as speed-limit detector mono, controlled by
IC1 and IC2 outputs. Bistable set-reset IC4 is also controlled by the
outputs of IC1 and IC2 and it (IC4), in turn, controls switching
on/off of the 100Hz (period = 0.01 second) astable timer IC5.
The time period of timer NE555 (IC1) count-start monostable
multivibrator is adjusted using preset VR1 or VR2 and capacitor C1. For
40kmph limit the time period is set for 9 seconds using preset \VR1,
while for 60kmph limit the time
period is set for 6 seconds using preset VR2. Slide switch S1 is used to
select the time period as per the speed limit (40 kmph and 60 kmph,
respectively).
The
junction of LDR1 and resistor R1 is
coupled to pin 2 of
IC1.Normally, light from the lase
keeps falling on the LDR sensor continuously and thus the LDR offers a
low resistance and pin 2 of IC1 is high.
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Whenever light falling on the LDR is interrupted by any vehicle, the
LDR resistance goes high and hence pin 2 of
IC1 goes low to trigger the monostable. As a result, output pin 3 goes
high for the preset period (9 or 6 seconds) and LED1 glows to indicate
it. Reset pin 4 is controlled by the output of NAND gate N3 at power-on
or whenever reset switch S2 is pushed.
For IC2, the monostable is triggered in the same way as IC1 when the
vehicle intersects the laser beam incident on
LDR2 to generate a small pulse for stopping the count and for use in the
speed detection. LED2 glows for the duration
for which pin 3 of IC2 is high. The outputs of IC1 and IC2 are fed to
input pins 2 and 1 of NAND gate N1, respectively. When the outputs of
IC1 and IC2 go high simultaneously
(meaning that the vehicle has crossed the preset speed limit), output pin
3 of gate N1 goes low to trigger monostable
timer IC3. The output of IC3 is used for driving piezobuzzer PZ1,
which alerts the operator of speed-limit violation.
Resistor R9 and capacitor C5 decide the time period for which the
piezobuzzer sounds. The output of IC1 triggers the bistable (IC4)
through gate N2 at the leading edge of the count-start pulse. When pin
10
2 of IC4 goes low, the high output at its pin 3 enables astable clock
generator IC5. Since the count-stop
pulse output of IC2 is connected to pin 6 of IC4 via diode D1, it resets
clock generator IC5. IC5 can also be reset via diode D2 at power-on as
well as when reset switch S2 is pressed.
IC5 is configured as an astable multivibrator whose time period is
decided by preset VR3, resistor R12 and capacitor C10. Using preset
VR1, the frequency of the astable multivibrator
is set as 100 Hz. The output of IC5 is fed to clock pin 1 of decade
counter/7- segment decoder IC6 CD4026. IC CD4026 is a 5-stage
Johnson
decade counter and an output decoder
that converts the
Johnson code into a 7-segment decoded output for driving
DIS1
display. The counter advances by one count at the positive clock signal
transition. The carry-out (Cout) signal from CD4026 provides one
clock after every ten clock inputs to clock the succeeding decade counter
in a multidecade counting chain. This is achieved by connecting pin 5
of each CD4026 to pin 1 of the next CD4026.
A high reset signal clears the decade counter to its zero count. Pressing
switch S2 provides a reset signal to pin 15 of all CD4026 ICs and also
IC1 and IC4. Capacitor C12 and resistor R14 generate the power-on-
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reset signal. The seven decoded outputs ‘a’ through ‘g’ of CD4026s
illuminate the proper segment of the 7-segment
displays (DIS1 through DIS4) used for representing the decimal digits
‘0’ through ‘9.’ Resistors R16 through R19 limit the current across
DIS1 through
DIS4, respectively. Fig. 3 shows the circuit of the power supply. The
AC mains is stepped down
by transformer X1 to deliver the secondary output of 15 volts, 500 mA.
The transformer output is rectified by a bridge rectifier comprising
diodes D3 through D6, filtered by capacitor C14 and regulated by IC11
to provide regulated 12V supply. Capacitor C15 bypasses any ripple in
the regulated
output. Switch S3 is used as the ‘on’/‘off’ switch. In mobile application
of the circuit, where mains 230V AC is not available, it is advisable to
use an external 12V battery. For activating the lasers used in conjunction
with LDR1 and LDR2, separate batteries may be used.
construction and working
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Assemble the circuit on a PCB. An actual-size, single-side PCB layout
for the speed checker is shown in Fig. 4 and its component layout in Fig.
5.Before operation, using a multimeter check whether the power supply
output is correct. If yes, apply power supply to the circuit by flipping
switch S3 to ‘on.’ In the circuit, use long wires for connecting the two
LDRs, so that you can take them out of the PCB and install on one side
of the highway, 100 metres apart. Install the two laser transmitters (such
as laser torches) on the other side of the highway exactly opposite to the
LDRs such that laser light falls directly on the LDRs. Reset the circuit
by pressing switch S2, so the display shows ‘0000.’ Using switch S1,
select the speed limit (say, 60 kmph) for the highway. When any vehicle
crosses the first laser light, LDR1 will trigger IC1. The output of IC1
goes high for the time set to cross 100 metres with the selected speed (60
kmph) and LED1 glows during for period. When the vehicle crosses the
second laser light, the output of IC2 goes high and LED2 glows for this
period. Piezobuzzer PZ1 sounds an alarm if the vehicle crosses the
distance between the laser set-ups at more than the selected speed (lesser
period than preset period). The counter starts counting when the first
laser beam is intercepted and stops when the second laser beam is
intercepted. The time taken by the vehicle to cross both the laser beams
is displayed on the 7-segment display. For 60kmph speed setting, with
timer frequency set at 100 Hz, if the display count is less than ‘600,’ it
means that the vehicle has crossed the speed limit (and simultaneously
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the buzzer sounds). Reset the circuit for monitoring the speed of the next
vehicle.
Note. This speed checker can check the speed of only one vehicle at a
time.
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Parts List
Semiconductors:
IC1-IC5 -
NE555 timer
IC6- IC9 -
CD4026 decade
counter/7-segment
decoder
IC10 -
CD4011 NAND gate
IC11 -
7812 12V regulator
D1, D2 -
1N4148 switching diode
D3-D6 -
1N4007 rectifier diode
LED1 -
Green LED
LED2, LED3 -
Red LED
DIS1-DIS4 -
LTS543 common-cathode, 7-segment display
Resistors (all ¼-watt, ±5% carbon):
R1, R4 R2, R5, R6,
100-kilo-ohm
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R8, R10,
R11, R14 -
10-kilo-ohm
R3, R7, R13,
R16-R19 -
470-ohm
R9 -
470-kilo-ohm
R12, R15 -
1-kilo-ohm
VR1, VR2 -
100-kilo-ohm preset
VR3 -
20-kilo-ohm preset
Capacitors:
C1 -
100µF, 25V electrolytic
C2, C4, C6,
C8, C11 -
0.01µF ceramic disk
C3, C13, C15 -
0.1µF ceramic disk
C5 -
10µF, 25V electrolytic
C7 -
0.47µF, 25V electrolytic
C9 -
0.2µF ceramic disk
C10 -
1µF, 25V electrolytic
C12 -
47µF, 25V electrolytic
C14 -
1000µF, 35V electrolytic
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Miscellaneous:
X1 -
230V AC primary to 0-
15V,
500mA secondary
transformer
PZ1 -
Piezobuzzer
LDR1, LDR2 - LDR
S1, S2 -
Push-to-on switch
S3 -
On/Off switch
-
Pointed laser ligh
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Components used
IC555 TIMER
One of the most versatile linear ICs is the 555 timer which was first
introduced in early 1970 by Signetic Corporation giving the name
as SE/NE 555 timer. This IC is a monolithic timing circuit that can
produce accurate and highly stable time delays or oscillation. Like other
commonly used op-amps, this IC is also very much reliable, easy to use
and
cheaper
in
cost.
It
has
a
variety
of
applications
including monostable andastable multivibrators, dc-dc converters, digital
logic probes, waveform generators, analog frequency meters and
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tachometers, temperature measurement and control devices, voltage
regulators etc. The timer basically operates in one of the two modes
either as a monostable (one-shot) multivibrator or as an astable (freerunning) multivibrator.The SE 555 is designed for the operating
temperature range from – 55°C to 125° while the NE 555 operates over
a temperature range of 0° to 70°C.
The important features of the 555 timer are :

It operates from a wide range of power supplies ranging from + 5
Volts to + 18 Volts supply voltage.

Sinking or sourcing 200 mA of load current.

The external components should be selected properly so that the
timing intervals can be made into several minutes Proper selection
of only a few external components allows timing intervals of
several minutes along with the frequencies exceeding several
hundred kilo hertz.

It has a high current output; the output can drive TTL.

It has a temperature stability of 50 parts per million (ppm) per
degree Celsius change in temperature, or equivalently 0.005 %/ °C.

The duty cycle of the timer is adjustable with the maximum power
dissipation per package is 600 mW and its trigger and reset inputs
are logic compatible.
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2. IC Pin Configuration
555 Timer IC Pin Configuration
The 555 Timer IC is available as an 8-pin metal can, an 8-pin mini DIP
(dual-in-package) or a 14-pin DIP.
This IC consists of 23 transistors, 2 diodes and 16 resistors. The
explanation of terminals coming out of the 555 timer IC is as follows.
The pin number used in the following discussion refers to the 8-pin DIP
and 8-pin metal can packages.
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CD4026B
CD4026B and CD4033B each consist of a 5-stage Johnson decade
counter and an output decoder which converts the Johnson code to a 7segment decoded output for driving one stage in a numerical display.
These devices are particularly advantageous in display applications
where low power dissipation and /or low package count are important.
Inputs common to both types are CLOCK, RESET, & CLOCK
INHIBIT; common outputs are CARRY OUT and the seven decoded
outputs (a, b, c, d, e, f, g). Additional inputs and outputs for the
CD4026B include DISPLAY ENABLE input and DISPLAY ENABLE
and UNGATED "C-SEGMENT" outputs. Signals peculiar to the
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CD4033B are RIPPLE-BLANKING INPUT AND LAMP TEST INPUT
and a RIPPLE-BLANKING OUTPUT.
A high RESET signal clears the decade counter to its zero count. The
counter is advanced one count at the positive clock signal transition if
the CLOCK INHIBIT signal is low. Counter advancement via the clock
line is inhibited when the CLOCK INHIBIT signal is high. The CLOCK
INHIBIT signal can be used as a negative-edge clock if the clock line is
held high. Antilock gating is provided on the JOHNSON counter, thus
assuring proper counting sequence. The CARRY-OUT (Cout) signal
completes one cycle every ten CLOCK INPUT cycles and is used to
clock the succeeding decade directly in a multi-decade counting chain.
The seven decoded outputs (a, b, c, d, e, f, g) illuminate the proper
segments in a seven segment display device used for representing the
decimal numbers 0 to 9. The 7-segment outputs go high on selection in
the CD4033B; in the CD4026B these outputs go high only when the
DISPLAY ENABLE IN is high.
The CD4026B- and CD4033B-series types are supplied in 16-lead dualin-line plastic packages (E suffix), 16-lead small-outline packages (NSR
suffix), and 16-lead thin shrink small-outline packages (PW and PWR
suffixes).
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Features

Counter and 7-segment decoding in one package

Easily interfaced with 7-segment display types

Fully static counter operation: DC to 6 MHz (typ.) at VDD = 10 V

Ideal for low-power displays

Display enable output (CD4026B)

"Ripple blanking" and lamp test (CD4033B)

100% tested for quiescent current at 20 V

Standardized, symmetrical output characteristics

5-V, 10-V, and 15-V parametric ratings

Schmitt-triggered clock inputs

Meets all requirements of JEDEC Tentative Standard No. 13B,
"Standard Specifications for Description of ’B’ Series CMOS Devices"

Applications
o
Decade counting 7-segment decimal display
o
Frequency division 7-segment decimal displays
o
Clocks, watches, timers (e.g. ÷60, ÷60, ÷ 12 counter/display)
o
Counter/display driver for meter applications
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RESISTANCE
Resistance is the opposition of a material to the current. It is measured in
Ohms (
no conductor is 100% efficient. To control the electron flow (current) in
a predictable manner, we use resistors. Electronic circuits use calibrated
lumped resistance to control the flow of current. Broadly speaking,
resistor can be divided into two groups viz. fixed & adjustable (variable)
resistors. In fixed resistors, the value is fixed & cannot be varied. In
variable resistors, the resistance value can be varied by an adjuster knob.
It can be divided into (a) Carbon composition (b) Wire wound (c)
Special type. The most common type of resistors used in our projects is
carbon type. The resistance value is normally indicated by colour bands.
Each resistance has four colours, one of the band on either side will be
gold or silver, this is called fourth band and indicates the tolerance,
others three band will give the value of resistance (see table). For
example if a resistor has the following marking on it say red, violet,
gold. Comparing these coloured rings with the colour code, its value is
27000 ohms or 27 kilo ohms and its tolerance is ±5%. Resistor comes in
various sizes (Power rating). The bigger, the size, the more power rating
of 1/4 watts. The four colour rings on its body tells us the value of
resistor value as given below.
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COLOURS
CODE
Black -------------------------------------- 0
Brown ------------------------------------- 1
Red ---------------------------------------- 2
Orange ------------------------------------ 3
Yellow ------------------------------------ 4
Green -------------------------------------- 5
Blue---------------------------------------- 6
Violet -------------------------------------- 7
Grey --------------------------------------- 8
White -------------------------------------- 9
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The first rings give the first digit. The second ring gives the second digit.
The third ring indicates the number of zeroes to be placed after the
digits. The fourth ring gives tolerance (gold ±5%, silver ± 10%, No
colour ± 20%)
In variable resistors, we have the dial type of resistance boxes. There is a
knob with a metal pointer. This presses over brass pieces placed along a
circle with some space b/w each of them.Resistance coils of different
values are connected b/w the gaps. When the knob is rotated, the pointer
also moves over the brass pieces. If a gap is skipped over, its resistance
is included in the circuit. If two gaps are skipped over, the resistances of
both together are included in the circuit and so on.A dial type of
resistance box contains many dials depending upon the range, which it
has to cover. If a resistance box has to read upto 10,000Ω, it will have
three dials each having ten gaps i.e. ten resistance coils each of
resistance 10Ω. The third dial will have ten resistances each of 100Ω.
26
DIODE
The simplest semiconductor device is made up of a sandwich of P-type
semiconducting material, with contacts provided to connect the p-and ntype layers to an external circuit. This is a junction Diode. If the positive
terminal of the battery is connected to the p-type material (cathode) and
the negative terminal to the N-type material (Anode), a large current will
flow. This is called forward current or forward biased.
If the connections are reversed, a very little current will flow. This is
because under this condition, the p-type material will accept the
electrons from the negative terminal of the battery and the N-type
material will give up its free electrons to the battery, resulting in the
state of electrical equilibrium since the N-type material has no more
electrons. Thus there will be a small current to flow and the diode is
called Reverse biased.
Thus the Diode allows direct current to pass only in one direction while
blocking it in the other direction. Power diodes are used in concerting
AC into DC. In this, current will flow freely during the first half cycle
(forward biased) and practically not at all during the other half cycle
(reverse biased). This makes the diode an effective rectifier, which
convert ac into pulsating dc. Signal diodes are used in radio circuits for
detection. Zener diodes are used in the circuit to control the voltage.
27
Some common diodes are:1. Zener diode.
2. Photo diode.
3. Light Emitting diode.
28
CAPACITORS
It is an electronic component whose function is to accumulate charges and
then release it.
To understand
the
concept
capacitance,
consider
a
pair
of
of
metal plates which all are placed near to each other without touching. If
a battery is connected to these plates the positive pole to one and the
negative pole to the other, electrons from the battery will be attracted
from the plate connected to the positive terminal of the battery. If the
battery is then disconnected, one plate will be left with an excess of
electrons, the other with a shortage, and a potential or voltage difference
will exists between them. These plates will be acting as capacitors.
Capacitors are of two types: - (1) fixed type like ceramic, polyester,
electrolytic capacitors-these names refer to the material they are made of
aluminium foil. (2) Variable type like gang condenser in radio or
trimmer. In fixed type capacitors, it has two leads and its value is written
over its body and variable type has three leads. Unit of measurement of a
capacitor is farad denoted by the symbol F. It is a very big unit of
capacitance.
29
Small
unit
capacitor
are
pico-farad
denoted
by
pf
(Ipf=1/1000,000,000,000 f) Above all, in case of electrolytic capacitors,
it's two terminal are marked as (-) and (+) so check it while using
capacitors in the circuit in right direction. Mistake can destroy the
capacitor or entire circuit in operational.
30
PCB FABRICATION
The first step of assembling is to produce a printed circuit board. The
fabrication of the program counter plays a crucial role in the electronic
field. The success of the circuit is also dependent on the PCB. As far as
the cost is concerned, more than 25% of the total cost is for the PCB
design and fabrication.
The board is designed using a personal computer. The layout is drawn
using the software “Adobe PageMaker 6.5”. The layout is printed in a
“buffer sheet” using a laser procedure. First, a negative screen of the
layout is prepared with the help of a professional screen printer. Then
the copper clad sheet is kept under this screen. The screen printing ink is
poured on the screen and brushed through the top of the screen. The
printed board is kept under shade for few hours till the ink becomes dry.
The etching medium is prepared with the un-hydrous ferric chloride
water. The printed board is kept in this solution till the exposed copper
dissolves in the solution fully. After that the board is taken out and
rinsed in flowing water under a tap. The ink is removed with solder in
order to prevent oxidation. Another screen, which contains component
side layout, is prepared and
31
the same is printed on the component side of the board. A paper epoxy
laminate is used as the board. Both the component and the track layout
of the peripheral PCB is given at the end of this report.
A printed circuit board (PCB) mechanically supports and electrically
connects electronic components using conductive tracks, pads and other
features etched from copper sheets laminated onto a non-conductive
substrate. PCB's can be single sided (one copper layer), double sided
(two copper layers) or multi-layer. Conductor on different layers are
connected with plated-through holes called vias. Advanced PCB's may
contain components - capacitors, resistors or active devices - embedded
in the substrate.
Printed circuit boards are used in all but the simplest electronic products.
Alternatives to PCBs include wire wrap and point-to-point construction.
PCBs are more costly to design but allow automated manufacturing and
32
assembly. Products are then faster and cheaper to manufacture, and
potentially more reliable.
Much of the electronics industry's PCB design, assembly, and quality
control follows standards published by the IPC organization.
When the board has only copper connections and no embedded
components it is more correctly called a printed wiring board (PWB) or
etched wiring board. Although more accurate, the term printed wiring
board has fallen into disuse. A PCB populated with electronic
components is called a printed circuit assembly (PCA), printed circuit
board assembly or PCB assembly (PCBA). The IPC preferred term for
assembled boards is circuit card assembly (CCA), for assembled
backplanes it is backplane assemblies. The term PCB is used informally
both for bare and assembled boards.
33
Design
A board designed in 1967; the sweeping curves in the traces are
evidence of freehand design using self-adhesive tape.
Printed circuit board artwork generation was initially a fully manual
process done on clear mylar sheets at a scale of usually 2 or 4 times the
desired size. The schematic diagram was first converted into a layout of
components pin pads, then traces were routed to provide the required
interconnections. Pre-printed non-reproducing mylar grids assisted in
layout, and rub-on dry transfers of common arrangements of circuit
elements (pads, contact fingers, integrated circuit profiles, and so on)
helped standardize the layout. Traces between devices were made with
34
self-adhesive
tape.
The
finished
layout
"artwork"
was
then
photographically reproduced on the resist layers of the blank coated
copper-clad boards.
Modern practice is less labor intensive since computers can
automatically perform many of the layout steps. The general progression
for a commercial printed circuit board design would include:
1. Schematic capture through an electronic design automation tool.
2. Card dimensions and template are decided based on required
circuitry and case of the PCB. Determine the fixed components
and heat sinks if required.
3. Deciding stack layers of the PCB. 1 to 12 layers or more
depending on design complexity. Ground plane and power plane
are decided. Signal planes where signals are routed are in top layer
as well as internal layers.
4. Line impedance determination using dielectric layer thickness,
routing copper thickness and trace-width. Trace separation also
taken into account in case of differential signals. Microstrip,
stripline or dual stripline can be used to route signals.
5. Placement of the components. Thermal considerations and
geometry are taken into account. Vias and lands are marked.
6. Gerber file generation for manufacturing.
35
In the design of the PCB artwork, a power plane is the counterpart to the
ground plane and behaves as an AC signal ground, while providing DC
voltage for powering circuits mounted on the PCB. In electronic design
automation (EDA) design tools, power planes (and ground planes) are
usually drawn automatically as a negative layer, with clearances or
connections to the plane created automatically.
Application
It will maintain the softy of human life on the road.
It can also be used on the bridge for the control of the speed.
It can be used on the highway express, highway.
Conclusion
Here we implemented the “SPEED CHECKER FOR HIGHWAY” from
point of view of safety on the mega highway.
We feel that if mega highway is supported with such on faithful system
then it will not only help to maintain the traffic rules also reduces
36
accident.As circuit is compact and friendly one man can handle the
system efficiently.
References
www.wikipedia.com
www.google.com
www.kitsnspares.com