ANUGRAH NARAYAN COLLEGE
B.Sc ELECTRONICS [THIRD YEAR]
PROJECT WORK
2022
ELECTRONICS
ASSIGNMENT
PROJECT REPORT ON TOUCH SWITCH
PRESENTATION BY : AKASH KUMAR
Roll No. : 2020111030006
Reg. No. : 192011611103013
B.Sc ELECTRONICS
[THIRD YEAR]
PROJECT REPORT
ON
TOUCH SWITCH
CERTIFICATE
This is cerTify ThaT The final ProjecT rePorT enTiTled “Touch
swiTch” submiTTed
for The requiremenT for The degree of “B.Sc ELECTRONICS ”,
Is a work carried out by AKASH KUMAR (Roll. No. :
2020111030006, Reg. No. : 192011611103013) under my supervision
and guidance.
Place:
Date:
Head of the Department Project Co-ordinator Project Supervisor
ACKNOWLEDGEMENT
I am glad in presenting this project report based on Quality of Work Life In my effort
would be considered fruitful if it helps the organization and its readers in one way or
the other.
I externally my he artful appreciation to all, who had contributed to this
assignment/both explicitly and implicitly. Contributions made by each of them have
been equally valuable.
I am thankful to ( Jyotish Sir (H.O.D), Manoj Sir, Amitabh Sir, E.T.C) for giving me
valuable time, guidance and support to gain insights in making the project.
I wish to express my deep sense of gratitude especially to “Ms. RITU KAUNDLIYA ”
to supervise me in my project. It was her understanding and help that stimulated me
during the moments of difficulties.
Last but not the least, our sincere thanks to all the faculties of Electronics
department. Friends for installing this idea or sense of self-confidence.
AKASH KUMAR
(Roll No. 2020111030006 )
B.Sc. ELECTRONICS ( Third Year)
ABSTRACT
A touch switches apparatus for detecting the presence of an object such as a human
appendage, the apparatus having a switch and a local control circuit connected to the
switch and to a controlled device. The control circuit is preferably in integrated circuit
form Electronic on/off switch for a load connected to an a-c supply network, including
a controlled semiconductor switch connected in a series circuit with the load, control
circuit.
First of all let us consider a few basics in building electronic circuits on a printed circuit
board. Smart Kit boards also come pre-drilled and with the outline of the components
and their identification printed on the component side to make construction easier. The
soldering iron that you use must be light and its power should not exceed the 25
Watts.
Make sure that you do not use more solder than it is necessary as you are running the
risk of short-circuiting adjacent tracks on the board, especially if they are very close
together. - After having finished your work cut off the excess of the component leads
and clean the board thoroughly with a suitable solvent to remove all flux residues that
still remain on it.
The switch only has eight components and its construction is very easy even for the
most inexperienced. As usual construction must start from the least sensitive to heat
components, which in this case are the IC socket and the pins. After soldering the pins
and the socket, make the two jumper connections that are marked on the component
side of the board, solder the relay in its place and continue with the transistor the diode
and the LED.
Then, place the IC in its socket. The IC is of the CMOS family and should be handled
with great care as it can be damaged very easily from static discharges. Avoid touching
its pins and keep your body and the circuit board grounded during insertion. You
should also take care not to bent any pins underneath the IC body during this
operation.
LIST OF NOTATION & SYMBOLS
1. TTP223 TOUCH SWITCH
2. 1 CHANNEL 5V RELAY MODULE WITHOUT OPTOCOUPLER
3. BC547 NPN General Purpose Transistor
4. RESISTOR
5. BULB HOLDER
6. CONNECTING WIRES
TABLE OF CONTENTS
➢ INTRODUCTION
➢ CIRCUIT DIAGRAM
➢ DETAIL OF COMPONENT
1. TTP223 TOUCH SWITCH
2. 1 CHANNEL 5V RELAY MODULE WITHOUT OPTOCOUPLER
3. BC547 NPN General Purpose Transistor
4. Resistor
5. Diode
➢ CONSTRUCTION
➢ WORKING
1. If it doesn’t work
➢ ADVANTAGE
➢ DISADVANTAGE
➢ APPLICATION
➢ CONCLUSION
INTRODUCTION
A touch switch is an electronic device that enables us to control a circuit by simply touching
two wires. A simple touch switch circuit using TTP223 Touch Sensor Switch is given here.
The TTP223 is as a flip flop here. The ouch sensing area of to touch switch module work as
the set and reset contacts respectively. Sensors like TTP223 require requires a very low current
for controlling its gates. Since the TTP223 terminals are connected in as positive the logic
gates of the ICs will be in high state. When we touch through the touch sensing area the gates
of the IC will be closed and the output becomes low. This switches ON the transistor Q1 and
the relay gets activated. When we touch again through touch sensing area the gates again
becomes high and switches the transistor OFF. This makes the relay OFF. Thus by touching
through the touch sensing area the appliance connected through the relay can be switched ON
and OFF.
A touch switch is an electronic device that enables us to control a circuit by simply touching a
sensor. Smart Kit 1005 is a very easy project to built and will make you the proud owner of a
magic switch that will respond to the slightest touch of your hand on its sensitive plates.
Technical Specifications - Characteristics
Supply voltage: 5 VDC
Max. current:30 mA
Relay rating: 250 V/2 A
CIRCUIT DIAGRAM
PCB OF THE CIRCUIT
DETAIL OF COMPONENT
TTP223 TOUCH SWITCH
TTP223 or the touch sensor which we commonly use works as a capacitive touch switch which is
ideal for driving devices under microcontroller working voltage range. TTP223 touch sensor is the
very common sensor that is used to control the system with human interface with the system. TTP
capacitive touch sensor, widely used sensor in automation and project. So, here we are talking
about, “what is TTP223 touch sensor?” The touch sensor can be used in home automation and in
many other household things. Like you can attach the sensor to the wall on any other places
Touch Sensor are used for controlling the system or device physically with the touch response of
body to sensor. It comes in various sizes and multiple sensor points in single module variants. This
sensor seems to be small in comparison to other, but the touch sensitivity of this sensor is good for
beginner purposes.
The only drawback of the most common Capacitive touch sensor i.e., TTP223 touch sensor is that is
does not have any sensitivity control potentiometer or trimmer capacitor available o the module. The
sensor also can be found in two variants, TTP223-BA6 & TTP223N-BA6. The pros & cons of the
both IC’s is opposite to each other, which we’ll discuss in later part of the article.
1 CHANNEL 5V RELAY MODULE WITHOUT OPTOCOUPLER
Relay is an electromechanical device that uses an electric current to open or close the contacts of a
switch. The single-channel relay module is much more than just a plain relay, it comprises of
components that make switching and connection easier and act as indicators to show if the module is
powered and if the relay is active or not.
Single-Channel Relay Module Pin Description
Pin Number Pin Name Description
1 Relay Trigger Input to activate the relay
2 Ground 0V reference
3 VCC Supply input for powering the relay coil
4 Normally Open Normally open terminal of the relay
5 Common Common terminal of the relay
6 Normally Closed Normally closed contact of the relay
Single-Channel Relay Module Specifications
• Supply voltage – 3.75V to 6V
• Quiescent current: 2mA
• Current when the relay is active: ~70mA
• Relay maximum contact voltage – 250VAC or 30VDC
• Relay maximum current – 10A
BC547 NPN General Purpose Transistor
BC547 is a bipolar junction transistor (BJT).It is kind of an NPN transistor.It has three terminals:
Emitter, Collector and Base.The maximum current gain of BC547 is 800A.The Collector−Emitter
Voltage is 65V.The Collector-Base Voltage is 80V.The Emitter-Base voltage is 8V.
BC547 has two operation status: forward bias and reverse bias.In the status of the forward bias, the
current can pass when the collector and emitter are connected. While in the status of the reverse
bias, it acts as a disconnect switch and current cannot pass.
BC547 is usually used for current amplifier, quick switching and pulse-width modulation
(PWM).Therefore, if you need to control the speed of a motor or actuator in some of your projects,
you can simply use this transistor to achieve it. In addition, it can also be used as a switch that you
can easily switch on or off a DC device with this transistor.
CONSTRUCTION
First of all let us consider a few basics in building electronic circuits on a printed circuit
board.
The board is made of a thin insulating material clad with a thin layer of conductive
copper that is shaped in such a way as to form the necessary conductors between the
various components of the circuit. The use of a properly designed printed circuit board
is very desirable as it speeds construction up considerably and reduces the possibility
of making errors. Smart Kit boards also come pre-drilled and with the outline of the
components and their identification printed on the component side to make
construction easier. To protect the board during storage from oxidation and assure it
gets to you in perfect condition the copper is tinned during manufacturing and
covered with a special varnish that protects it from getting oxidised and makes
soldering easier.
Soldering the components to the board is the only way to build your circuit and from
the way you do it depends greatly your success or failure. This work is not very
difficult and if you stick to a few rules you should have no problems. The soldering
iron that you use must be light and its power should not exceed the 25 Watts. The tip
should be fine and must be kept clean at all times. For this purpose come very handy
specially made sponges that are kept wet and from time to time you can wipe the hot
tip on them to remove all the residues that tend to accumulate on it.
DO NOT file or sandpaper a dirty or worn out tip. If the tip cannot be cleaned, replace
it. DO NOT use soldering flux apart from that which is already included in your solder.
Too much flux can cause many problems and is one of the main causes of circuit
malfunction. If nevertheless you have to use extra flux, as it is the case when you have
to tin copper wires, clean it very thoroughly after you finish your work. In order to
solder a component correctly you should do the following:
Clean the component leads with a small piece of emery paper. - Bend them at the
correct distance from the component body and insert the component in its place on
the board. You may find sometimes a component with heavier gauge leads than usual,
that are too thick to enter in the holes of the p.c. board.
In this case use a mini drill to enlarge the holes slightly. Do not make the holes too
large as this is going to make soldering difficult afterwards.
Take the hot iron and place its tip on the component lead while holding the end of the
solder wire at the point where the lead emerges from the board. The iron tip must
touch the lead slightly above the p.c. board.
When the solder starts to melt and flow wait till it covers evenly the area around the
hole and the flux boils and gets out from underneath the solder. The whole operation
should not take more than 5 seconds. Remove the iron and let the solder to cool
naturally without blowing on it or moving the component.Take care not to overheat
the tracks as it is very easy to lift them from the board and break them.
Put the one of the 1k Ohm resistor at place marked as R1 and and the second 1k
Ohm resistor at place marked as R2 on the PCB board. Then put the IN4007 diode at
the place marked as D1, then put the 1 channel 5v relay on the square shaped
marked on the pcb. Then keep a LED bulb at the LED 1 marked place. After these, put
the BC547 transistor at the place marked T1. In the end keep the TTP223 touch
sensor on its marked place.
The pcb is designed such that BC547 transistor’s base leg is connected to the I/O
terminal of the TTP223 touch sensor module, and the transistor’s emitter leg is
connected to the GND terminal of the touch sensor module.
Then connect the transistor’s collector leg to the negative terminal of the Relay. After
that the Vcc point of the touch sensor module is connected to the positive terminal of
the relay. The input of +5V is given to the +Ve terminal of the relay and -5Ve input is
given to the emitter leg of the BC547 transistor.
After making all these connections, we have to make a modification into the TTP223
Touch Switch module. We have to short the B point inscribed on the Touch Switch
module. This modification will help the touch module to remember the last command
given to the touch switch.
The Output -Ve terminal is given from the No terminal of the 5V relay to the
electronic equipment to be controlled by the Touch switch. In the last the electronic
equipment to be controlled's -Ve or +Ve terminal is connected to No point and from
Com terminal the command goes to the connected electronic equipment.
WORKING
The working of the TTP223 touch sensor IC is very simple, it can be understood easily
through a thorough reading of the datasheet which is provided above. This IC comes
in a SOT-23 6L package which is for both packages, either TTP23 & TTP223N. The 4
pins which are used other than Power pins are used for various changes. Q pin in the
above circuit is the output pin which giver either high or low output which gives signal
to the microcontroller the state of this pin can be changed according to the table
mentioned below.
The sensitivity of the sensor can be changed via changing the Cs capacitor in the
circuit diagram. Which is connected to the Input pin of the IC & GND and in parallel
with the touchpad. Upon touching the pad, the capacitance of the circuit increases and
hence the IC registers the touch.
The relay uses an electric current to open or close the contacts of a switch. This is
usually done using the help of a coil that attracts the contacts of a switch and pulls
them together when activated, and a spring pushes them apart when the coil is not
energized.
There are two advantages of this system – First, the current required to activate the
relay is much smaller than the current that relay contacts are capable of switching, and
second, the coil and the contacts are galvanically isolated, meaning there is no electrical
connection between them. This means that the relay can be used to switch mains
current through an isolated low voltage digital system like a microcontroller.
When we touch the touch sensing area of the TTP223 touch switch module it to
triggers the modules output which causes the switch output to switch from its idle
low state to high (default operation).
As the Touch Switch is touched the relay and the LED will get activated. It will be
high till the time the touch sensor module is touched again which shows that in one
touch the relay will be high and in second touch the relay will be low.
When the relay is in high mode the current will flow through it resulting into
completion of the circuit, which will activate the connected device.
When the relay is in low mode the current will not flow through it resulting into
disconnection of the circuit, which will deactivate the connected device.
If It Does Not Work
Check your work for possible dry joints, bridges across adjacent tracks or soldering
flux residues that usually cause problems.-Check again all the external connections to
and from the circuit to see if there is a mistake there. Make sure that all the polarized
components have been soldered the right way round. Make sure the supply has the
correct voltage and is connected the right way round to your circuit. Make sure that
you have inserted the IC in its socket correctly and that you have not bent any pins
during insertion. Check your project for faulty or damaged components.
ADVANTAGE
There are no mechanical components in a capacitive switch, resulting in a longer
lifespan when compared to their mechanical counterpart. Additionally, capacitive
switches can withstand some of the harshest environments, including outdoor
environments. If the intrusion of dirt, dust or moisture is a concern, capacitive is
probably the best option for an electrical switch.
1. Beautiful and aesthetically appealing appearance; strong graphic clarity;
straight-forward design.
2. Sealed design ensuring top performance and wear resistance; anti-fade and
non-deformation; long life span.
3. Waterproof and anti-interference.
4. No metal contact; simple structure; low cost.
5. Operation comfort; excellent sensitivity.
6. It can realize intellectualization and operate more conveniently.
7. Its reliability can replace various panels, such as metal keypads, membrane
keypads, etc.
DISADVANTAGE
1. Tactile – object must be “touched” to know it exists
2. Low range
3. Less accurate for acquiring range data – you only know that there is an object
there within the motion range of the switch – not exactly how far it is, or exactly
where the sensed object’s XY position is relative to the robots position
APPLICATION
1. This is ideally useful for making touch operated doorbells , buzzer , toys etc
.
2. It also used in door knobs & in relays .
3. Use this project to make remote operated switch , light operated switch &
clap switch .
4. Touch sensor in robotics; a touch sensor is commonly used in robots, enabling
basic movement and the ability to detect touch in its surroundings (E.g. When
the robot runs into something, the touch sensor can have it to stop moving)
5. Smartphones, automotive, industrial applications
6. Touch sensor faucet in kitchens; allowing for control of running water without
having to physically turn the knob
7. Most other applications that require pressure/distance measurement
CONCLUSION:-
We can turn on almost any electrical device with this switch & the switch
automatically turns off a short time later. It is used in various applications
because of its quicker response. It is very simple.
The switch also contains an additional general function. By touching several
surfaces simultaneously or within a pre-defined time, the additional function can be
activated. This invention concerns a multiple touch switch for operating lighting,
this is in contrast to the current systems in which only a single button in a multiple
switch can be used to turn lights on or off or in which a separate button for each
light circuit has to be pressed.
Thank You
The End
Your Sincerely
Akash Kumar
