“Towards Global Technological Excellence”

A Minor Project Report

on

Time Delay Relay Circuit

By
Ashutosh Diwate (21004059)

Guide

S. J. Meshram (Asst. Professor)

DEPARTMENT OF ELECTRONICS ENGINEERING

GOVERNMENT COLLEGE OF ENGINEERING, AMRAVATI

(An Autonomous Institute of Government of Maharashtra)Amravati,

444604

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 Government College of Engineering, Amravati
(An Autonomous Institute of Government of Maharashtra)

Department of Electronics

CERTIFICATE

This is to certify that Ashutosh Diwate (ID-21004059), student of Third Year B. Tech in Electronics and
Telecommunication Engineering, has submitted this minor project report for the title “Time Delay Relay
Circuit”, which is being submitted herewith for the completion of 6th semester of B. Tech. in Electronics and
Telecommunication Engineering of Government College of Engineering Amravati, is the result of the work
completed under my supervision and guidance of any degree.

S. J. Meshram

(Asst. Professor)

Guide

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ACKNOWLEDGMENT

In this part of report, I would like to express my deep sense of gratitude and sincere
thanks to all those illumination because of whom, this work has become successful.

I am highly indebted to S. J. Meshram for her guidance and constant supervision as

well as for providing necessary information regarding the project and also for her support
in completing the project.

I also like to acknowledge efforts of Mr. Pravin Ambekar for conducting workshop
on “PCB Designing” a three-day workshop defining and training the basics of PCB making.

I am grateful for our HOD Dr. P. R. Deshmukh for scheduling workshop for PCB designing.

I also thankful to the staff members of Electronics and Telecommunication

Department who has directly and indirectly helped in completion of the project.

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 INDEX
1. INTRODUCTION

1.1 Preface

1.2 Organization of Report

2. METHODOLOGY (PCB DESIGNING)

2.1 PCB Composition & Materials

2.2 Design Requirement 2.3 Schematic

2.4 Footprint and Layout

2.5 Printing PCB

2.6 Etching and Drilling

2.7 Soldering

3. IMPLEMENTATION

IV
 3.1 Components

3.2 Constructed Circuit

3.3 Principle of Operation

3.4 Costing

4. RESULTS

4.1 Observation

4.2 Conclusion

4.3 Merits

LIST OF ACRONYMS
DC: Direct Current

PCB: Printed Circuit Board CAD:

Computer-aided Design

LED: Light Emitting Diode

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 1. INTRODUCTION

1.1 Preface

The ever-growing desire for convenient and interactive technologies has

led to the exploration of touchless control methods. This project dives into the
construction of a motion sensor circuit, utilizing the ubiquitous LM555 integrated
circuit (IC).

This report delves into the theoretical framework and practical

implementation of the Motion sensor. We will begin by exploring the concept of
motion sensor and their potential applications in home automation, access control
systems, and even interactive toys.

Next, we will embark on a detailed exploration of the LM555 IC, a

fundamental building block in many electronic circuits. The report will explain the
different operating modes of the LM555 and how it is configured in this specific
project to function as a monostable timer.

Moving forward, we will meticulously dissect the various components

employed in the motion sensor circuit. This includes the condenser microphone,
responsible for converting motion into electrical signals, and the transistor, which
acts as an amplifier for the weak signal output. The report will elucidate the role
of resistors and capacitors in setting timing parameters and filtering unwanted
signals.

Following the component breakdown, the report will provide a step-by-step

guide for constructing the motion sensor circuit. This section will encompass
component selection based on desired functionality, circuit assembly techniques
using a breadboard or PCB, and crucial safety precautions to be observed while
working with electronics.

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 To ensure successful operation, the report will outline comprehensive
testing procedures. This will involve verifying the functionality of individual
components and evaluating the overall performance of the motion sensor circuit,
including sensitivity to motions and response time.

Finally, the report will conclude with a discussion of potential

improvements and future applications. This could involve incorporating additional
features like adjustable sensitivity or integrating the motion sensor circuit with
other electronic devices.

This project aims to empower students, hobbyists, and electronics

enthusiasts with the knowledge and skills to build a functional motion sensor
circuit. By understanding the underlying principles and implementing them
practically, you'll gain valuable insight into the applications of the LM555 and
delve into the exciting realm of sound-activated control systems.

1.2 Organization of Report

• Introduction: This chapter defines the objective. It encompasses the statement

of purpose.

• Methodology: In this section we have discussed the process of PCB making

with alternative step to for few processes.
• Implementation: Discusses the overall circuit design, components to be
mounted and their specification and the working.

• Result: This reflects the outcome of the circuit.

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 2. METHODOLOGY (PCB DESIGNING)

The unassuming rectangle that forms the heart of most electronics is a

marvel of miniaturization and engineering ingenuity. This ubiquitous component,
known as a Printed Circuit Board (PCB), is the foundation upon which modern
electronics are built. Imagine a thin, flat sheet crafted from a strong, insulating
material, similar to fiberglass. This serves as the base for a meticulously etched
network of copper traces, resembling a labyrinth of tiny golden wires laid out on
the surface. These intricately designed pathways, along with strategically placed
pads, act as the connective highways that allow various electronic components to
communicate with each other.

Think of a PCB as a miniaturized cityscape. Electronic components, like

resistors, capacitors, and integrated circuits, take the place of towering buildings.
The copper traces, then, become the electrical avenues that these miniaturized
structures rely on to function. But unlike a traditional city confined to a single
plane, PCBs can be much more intricate. Imagine a multi- layered cake, where
each layer represents a separate insulating sheet. These sheets are then
meticulously stacked and sandwiched together, with each layer containing its own
network of copper traces. This allows for an even more complex and sophisticated
network of connections to be established within the PCB. Through a combination
of heat and pressure, these individual layers are fused into a rigid and functional
unit. This innovative approach enables the creation of incredibly intricate circuits
within a remarkably compact space.

The advantages of PCBs are undeniable. By enabling the miniaturization

of complex circuitry, they have revolutionized the world of electronics. From the

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smartphones we carry in our pockets to the awe-inspiring spacecraft that explore
the cosmos, PCBs are the hidden heroes that make modern technology possible.
Their ability to condense intricate functionality into a compact form factor has
fueled innovation across countless industries and continues to shape the
technological landscape of the future.

2.1 PCB Composition & Materials

A copper-clad substrate or polyimide-based film is often used for flex circuits.
A solder mask is also used, which is a technique where everything on the circuit board
is coated with an epoxy-based LPI or cover coat for flex, except the contacts to be
soldered.

Fig 2.1 PCB Layer

2.2 Design Requirement

The road to a well-functioning PCB starts before you even touch your CAD
software. This crucial first step involves meticulously preparing your library
components and ensuring your circuit's logic is sound.

Imagine your schematic as the blueprint for your PCB. To construct this
blueprint, you'll need to build it using logic symbols. These symbols are essentially
simplified pictures of the real electronic components you'll be using, like resistors,
capacitors, transistors, and integrated circuits (ICs). In your case, you'll need logic
symbols for a condenser SPDT relay, a LM358 and CD4017 IC, a BC547
transistor, resistors of various values, a capacitor, an LED, a screw terminal, and

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even a 9V battery. But the beauty of electronics is that you can use these basic
building blocks to create more complex functionality. By strategically combining
these logic symbols in your schematic, you can design sophisticated circuits like
logic gates, precision amplifiers, or even filters, depending on what your project
aims to achieve.

However, the true magic lies in the logic development stage. This is where
you define how all these components will interact with each other. It's the blueprint
within the blueprint, the underlying roadmap that dictates how your circuit will
function. Taking the time to meticulously plan and refine your logic is paramount.
A well-defined logic plan ensures that your circuit performs exactly as you
envision it, transforming your design from theory into reality.
Once you've nailed down your logic and library components, it's time to
take stock of the physical parts you'll need. For this project, you'll be using a
combination of through-hole components and other essentials. The through-hole
components, which include the condenser microphone, the IC, the transistor, all
the resistors, the capacitor, and the LED, all share a common design feature – their
leads are designed to be inserted through holes drilled into the PCB and soldered
on the other side. You'll also need a screw terminal for connection purposes, a 9V
battery to power your circuit, and of course, the copper clad PCB itself, which will
serve as the foundation for your entire creation.

With your library components prepared, your logic clearly defined, and all
the necessary parts gathered, you'll be well-equipped to translate your design into
a functional reality using PCB design software. This initial groundwork might
seem tedious, but it's an essential investment that ensures a smooth and successful
journey towards realizing your PCB project.

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2.3 Schematic
Before we delve into the world of CAD software and start placing
components on a virtual canvas, there's an important preliminary step –
understanding schematics and how they translate your circuit's blueprint into
reality.

A schematic diagram is essentially a simplified map of your circuit. Unlike

a realistic picture, it uses standardized symbols to represent the various electronic
components you'll be using – resistors, capacitors, transistors, integrated circuits
(ICs), and more. Think of it as a language specifically designed to communicate
the functionality of your circuit, independent of the physical layout of the
components themselves. This means the arrangement of symbols on the schematic
might not directly correspond to how the components will be positioned on the
final PCB.

With this symbolic language in hand, it's time to organize your components
on a schematic sheet within your chosen CAD software. There are several open-
source platforms available specifically designed for PCB design, offering a user-
friendly environment to bring your circuit to life. Some popular options include
TinkerCAD, EasyEDA, and KiCAD. For this project, we'll be utilizing EasyEDA's
open-source software to translate our schematic into a functional PCB layout.
By familiarizing yourself with schematics and choosing the right software
platform, you've laid the essential groundwork for the next stage: meticulously
placing and connecting your components within the CAD software to create a clear
and well-organized schematic. This schematic will serve as the foundation for your
PCB design, ensuring a smooth transition from concept to a tangible, functioning
circuit.

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 Fig 2.2 Schematic Diagram

2.4 Footprint and Layout

The PCB footprint is defined as the physical interface among electronic
components or land pattern and printed circuit boards which also comprises of the
information of documentation such as reference, polarization mark, and outline.
Every component that will appear on a circuit board layout will have a PCB
footprint. Footprint pad guidelines are rules or suggestions that stipulate how pads
should be spaced from other pads, other surface elements, drill holes and the board
edge. They also define how pads for a single component should be arranged. All
PCB routing need to have copper that connects components on the surface layer or
internal layers, known as traces. Some of the important design routing
requirements:

1. The current carrying capacity of traces, as high current boards can

require large traces or even polygons.

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 2. Trace width to be used in the board, which will ensure
manufacturability and will affect crosstalk.

3. Any controlled impedance signals, which require specific width that

must be set based on the PCB stack-up.

4. Routing PCB topology, which will determine how traces branch

connect to multiple components.

Fig. 2.3 Tracks and Component position on EasyEda software

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 Fig. 2.4 Layout to be printed on Copper Clad PCB Board

2.5 Printing PCB

Once you've meticulously crafted your schematic and have a clear
understanding of PCB footprints and routing, it's time to translate your design into
a physical reality. This stage involves transferring your circuit layout onto the
copper surface of the copper-clad board, a process with several approaches.

Industry Standard: Photolithography with Laser or Inkjet Printers

The industrial standard for transferring circuit layouts utilizes a technology

called photolithography. This method leverages either laser or inkjet printers to
create a precise image of your circuit directly onto a special photosensitive film.
This film is then used to selectively expose a light-sensitive chemical coating
applied to the copper-clad board. After exposure and development, the unwanted
copper is etched away, leaving behind the desired circuit traces.

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DIY Alternatives: Pressing and Drawing

While photolithography offers high precision and accuracy, there are alternative
methods suitable for hobbyists or low-volume projects. Here are two popular DIY
techniques:

• Pressing: This method involves creating a mirror image of your circuit

layout on a sheet of transparent film or paper. The toner from the printout is
then transferred to the copper surface of the board by heat and pressure,
typically using a heating lamp or an electric iron press. A quick dip in a cold
bath helps the toner adhere to the copper surface. This transferred toner acts
as a mask during the etching process, protecting the desired copper traces
while the rest of the copper is etched away.

• Drawing: For a truly hands-on approach, you can bypass printing altogether
and directly draw the circuit layout onto the copper-clad board using a
permanent marker. Permanent markers are preferred because their ink is
designed to resist spreading or bleeding during the etching stage. This
method requires a steady hand and meticulous attention to detail, but it can
be a viable option for simpler circuits. Choosing the Right Technique

The best method for transferring your circuit layout depends on your
budget, desired precision, and access to resources. Photolithography offers the
highest accuracy and is the industry standard, but it requires specialized equipment
and materials. Pressing and drawing are more accessible DIY methods, but they
may not be suitable for complex circuits with intricate trace patterns.
Regardless of the technique you choose, understanding these methods equips
you with the knowledge to translate your digital design into a tangible, copper-clad
masterpiece, paving the way for etching and the creation of your functional PCB.

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2.6 Etching and Drilling
Wet etching involves using a chemical solution to selectively remove
copper from the PCB. The most popular solution for this purpose is ferric chloride,
a corrosive acidic compound.

Here's a breakdown of the wet etching process:

1. Submerge the PCB: The PCB with the transferred layout (toner or
marker) is submerged entirely in the ferric chloride solution.

2. Chemical Reaction: The ferric chloride reacts with the exposed copper,
slowly eating it away. The marker or toner acts as a protective mask,
preventing the etching solution from dissolving the desired copper traces.

3. Time for Etching: The etching time can vary depending on the thickness
of the copper clad and the strength of the ferric chloride solution. It
typically takes between 30 minutes to an hour to fully etch the copper.

4. Etching Complete: Once the etching process is complete, you'll be left

with only the protected copper traces adhering to the PCB, forming the
conductive pathways for your circuit.

Drilling the Foundation: Mounting Your Components

After etching, you'll need to drill holes into the PCB at specific locations.
These holes serve as mounting points for the various electronic components you'll
be using, such as resistors, capacitors, and integrated circuits. The location and size
of these holes are determined by the footprint pads (the copper landing areas for
components) defined in your schematic and PCB layout. A standard drill bit size
of 1mm is typically used for through-hole components, which have leads that are
inserted through these holes and soldered onto the pads on the opposite side of the
PCB.

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The Power of Choice: Selecting the Etching Technique

While wet etching is a popular and accessible method for hobbyists, it's
important to note that it's not the only option. For industrial PCB fabrication, dry
etching techniques using specialized equipment are employed to achieve higher
precision and accuracy. However, for most hobbyist projects, wet etching offers a
good balance of effectiveness and affordability.

By understanding the wet etching process and drilling techniques, you've

acquired the knowledge to transform your PCB layout from a copper-clad board
into a functional circuit board ready for component assembly. The journey towards
realizing your electronic creation is nearing completion.

Fig.2.5 Top Silk Layer

2.7 Soldering
As you approach the final stage of bringing your PCB to life, you'll be
wielding a tool that's essential for creating electrical connections – the soldering
iron. Soldering is the process of joining electronic components to your PCB using
a metal alloy with a low melting point, commonly referred to as solder.

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The Soldering Symphony: How it Works

Imagine this: you have two pieces of metal you want to connect electrically.
Soldering works by melting the solder and applying it to the mating surfaces. The
molten solder forms a strong bond with the metals when it cools and solidifies,
creating a permanent mechanical and electrical connection.

The PCB and Its Pads: A Match Made in Soldering Heaven

In the realm of PCB assembly, soldering plays a starring role. The

components you'll be using, like resistors and capacitors, typically have leads –
wire-like extensions designed to be soldered to the PCB. These leads are passed
through the holes you meticulously drilled earlier, and then soldered onto
designated areas on the opposite side of the PCB called pads. These pads are
specifically designed to provide a strong foundation for the solder joint. Soldering
Wire: The Melodic Metal
Solder wire, the consumable used in soldering, is a thin, metal alloy
specifically formulated to melt at a relatively low temperature. The most common
type of solder wire is lead-based, with a composition of 60% tin (Sn) and 40% lead
(Pb). This Sn60Pb40 solder has a melting point of around 180 degrees Celsius,
making it ideal for working with electronic components that can't withstand
extremely high temperatures.

Choosing the Right Note: Alternatives to Leaded Solder

While lead-based solder has been the traditional choice, it's important to
note that lead is a toxic substance. Due to environmental and health concerns, lead-
free solders are becoming increasingly common. These lead-free solders require a
higher melting point, so it's crucial to ensure your soldering iron is powerful
enough to handle them if you choose to go this route. With the knowledge of
soldering under your belt, you're well on your way to meticulously attaching your
electronic components to your PCB, creating the vital connections that will bring
your circuit to life. The next step will be to test and verify your creation, but for

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now, focus on mastering the art of soldering and transforming your PCB into a
populated masterpiece.

3. IMPLEMENTATION

3.1 Components
Table 3.1

Components Value Quantity

- 1
CD 4017 LM
358 IC - 1

Transistor BC547 - 1

Resistor 220 Ohm 4

Resistor 10K Ohm 1

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 1
Trimmer 10k Ohm

SPDT relay 5 Volts 1

1
Capacitor 100uF and 10uF

- 2
LED
- 1
Screw Terminal

IN 4007 1

Battery 9V 1

IR LED pair 1

Glass epoxy PCB - 1

1
Wooden box

IC Base - 1

Total 18

3.2 Constructed Circuit

Fig. 3.1 Components soldered on PCB from above

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 Fig. 3.2 Components soldered on PCB from below

3.3 Principle of Operation :

• If the Trigger Pin (Pin-2 of the 555 IC) senses any voltage less than 1/3rds of the
supply voltage, it turns ON the output.
• If the Threshold Pin (Pin-6 of the 555 IC) senses any voltage more than 2/3rds of
the supply voltage, it turns OFF the output.
• Whenever the output of the 555 IC is in OFF state, the Discharge Pin (Pin-7 of the
555 IC) acts as ground i.e, it is internally connected to 0V.

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 Initially, when this circuit is powered on, the output will be in the OFF state. Whenever
the output is OFF, the discharge pin (Pin 7) will be internally connected to 0V. So the
capacitor completely discharges and won’t be able to charge via the series resistor that
connects it to the positive input voltage.

3.5 Costing

Table 3.2 Cost of Components used

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4. RESULTS

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4.1 Observation

• Time Activated Control: Motion detector circuit offer a unique way to

interact with electronics using buttons

• Relatively Simple Circuit: The basic components like CD 4017, SPDT

relay, LM 358, and transistor suggest a circuit achievable for beginners in
electronics.

• Timing and Sensitivity: The use of a timer allows control over how long
the output device stays activated after a motion. Additionally, the need to
adjust sensitivity suggests the circuit might be susceptible to other far cry
motions.

• Project Potential: This circuit can be a building block for more complex
motion- activated projects.

4.2 Conclusion

• A relay is a constructive element used to control high power with

extremely less power consumption. These are also used for processing signals
& they can also be utilized like switches. Generally, a normal relay is an
electrical device that functions like an electrically operated switch. Once the
flow of current reaches the coil of the relay then the open contacts will get
closed, & the closed contacts will get open. Once there is no flow of current in
the relay coil, then contacts will come back to their original position. There are
different types of relay available in the market which are used based on the
requirement

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4.3 Merits

• Hands-Free Control: The biggest advantage is the hands-free operation.

This can be particularly beneficial for people with limited mobility or
situations where motion is occupied. Imagine turning on a light switch in
the dark without fumbling for it.
• Simple Construction: Motion sensor circuits often use readily available
components and require a moderate level of electronics knowledge,
making them a good project for beginners to learn about basic circuits and
soldering.
• Low Cost: The components used are generally inexpensive, keeping the
overall cost of building the circuit low.
• Novelty Factor: A motion sensor adds a fun and unique element to
controlling electronics. It can be a conversation starter and a great
introduction to the world of interactive circuits.

• Project Platform: The basic motion sensor circuit can be a foundation for
more complex motion-activated projects. With additional components, you
could create
motion-activated control .

4.4 Applications
• The time delay relays mainly involve in different commercial and industrial
applications like buildings, machines, HVAC, water segments, etc.
• Time delay relays are frequently utilized in machine control-based applications for
providing switching to cyclic machinery. So this can assist to avoid the equipment
from damaging or sticking.
• These relays are useful in delaying multiple lamp row switching in greenhouses or
production services. So this helps in conserving energy by simply avoiding lamps
from being switched on once they are not required.
• These are used for irrigation systems & Pump controls.
• These are used in HVAC systems for controlling centralized water systems & fans. So
this helps in conserving energy & maintaining buildings very comfortable.

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Limitations to Consider:

The disadvantages of time delay relay include the following.

• They have a complex structure.

• The size is large.
• They have a short life.
• These are expensive.
• Its accuracy is simply affected by the power frequency