Automatic Rising And Dropping Toilet Bowl Lid Engineering Essay

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This report will describe how the automatic rising & dropping toilet bowl lid functions. Infrared Sensor with Relay as a detector. Motor Control for controlling the signal going forward or reverse. 24V motor receive signal from motor control to move the lid up or down.

The plastic box cover with silicon will be use for the electronic board. This is to avoid water from licking into the circuit board. Short circuit will happen if the water splash into the circuit.

Chapter 1 - Project Introduction

1.1 System Overview 1

1.2 Introduction 2-3

1.3 Aim & Objective 4

Chapter 2- Literature Review

2.1 Transistor 5-6

2.2 Diode 7

2.3 Resistor 8

2.4 Capacitor 9-11

2.5 Relay 12-13

2.6 Component List 14

Chapter 3- Methodology of the project

3.1 Flow Chart 15

3.2 Schematic Diagram 16-19

3.3 Schematic diagram layout on front of the PCB 20

3.4 Schematic diagram layout on the back of the PCB 21

3.5 PCB Fabrication 22

Chapter 4- Operation and Process

4.1 Introduction 23

4.2 Operation of the system 24

4.3 Flow Chart 25

References 26

1.1 System Overview:

Automatic raising and dropping toilet bowl lid is a type of automatically system which will rise and drop the lid when detected user is near the toilet bowl. This project is design for sitting toilet bowl. The infrared sensor is use to detect user and give signal to the circuit to function.

With this project, toilet user will have more advantage on clean lid and more convenient.

1.2 Introduction:

Since long time ago, every housing area or building area will have a toilet. This is because every human will have urgent such as shitting, pissing and farting. So we need a toilet, and we more need a nice and clean toilet. To keep a toilet bowl clean is everyone responsibility. But mostly people after using the toilet never move up the lid. So some person when using this toilet will never move the lid up. So the lid will easy become dirty after people using that. When someone had to defecate, maybe they choosing to stand on the lid. It will make the lid broken and dirty and maybe will cause the person who standing on the toilet bowl lid injury or slip down. These kinds of problem mostly happen in shopping complex area toilet for MEN. For certain condition, some place only 1 toilet available (unisex), so this will cause a lot of inconvenience. Therefore, one method had been introduced to solve this issue. This one of the method is Automatic Rising & Dropping Toilet Bowl Lid.

Automatic Toilet Rising & Dropping Toilet Bowl Lid is using Infrared Detector With Relay, Motor Control and a Motor. The reason this I do this project as you can see in figure 1. Usually men toilet will be provide with this standing bowl. Refer to figure 2. Toilet bowl shown in figure 1 is design for people who need to defecate, so they can sit down and relax.

Figure 1

Figure 2

This project content 3 parts:

1. Infrared Sensor with Relay

2. Motor control (forward, reverse)

3. 12V Motor (20 rpm)

1.3 Aim and Objective

The aim and objectives of this project is to build up a clean and comfortable toilet bowl & the seat for user. This automatic rising & dropping toilet bowl lid will show how efficiency it is and what benefit will be gained by using this project.

This report will describe how the automatic rising & dropping toilet bowl lid functions. Infrared sensor with relay work as detector. Motor Control for controlling the signal going forward or reverse. 24V motor receive signal from motor control to move the lid up or down.

The plastic box cover with silicon will be use for the electronic board. This is to avoid water from licking into the circuit board. Short circuit will happen if the water splash into the circuit.

Chapter 2- Literature Review

2.1 Transistor

The transistor is a solid state semiconductor device that can be used for amplification, switching, voltage stabilization, signal modulation and many other functions. It allows a variable current, from an external source, to flow between two of its terminals depending on the voltage or current applied to a third terminal. Transistors are made either as separate components or as part of an integrated circuit.

Transistors are divided into two main categories: bipolar junction transistors (BJTs) and field effect transistors (FETs). Transistors have three terminals where, in simplified terms, the application of current (BJT) or voltage (FET) to the input terminal increases the conductivity between the other two terminals and hence controls current flow through those terminals. The physics of this "transistor action" are quite different for the BJT and FET; see the respective articles for further details.

In analog circuits, transistors are used in amplifiers, (direct current amplifiers, audio amplifiers, radio frequency amplifiers), and linear regulated power supplies. Transistors are also used in digital circuits where they function as electrical switches. Digital circuits include logic gates, random access memory (RAM), and microprocessors.

PNP P-channel

NPN N-channel BJT JFET

2.2 Doide

In electronics, a diode is a component that restricts the direction of movement of charge carriers. It allows an electric current to flow in one direction, but essentially blocks it in the opposite direction. Thus the diode can be thought of as an electronic version of a check valve.

Circuits that require current flowing in only one direction will typically consist of one or more diodes in the circuit design.

Early diodes included "cat's whisker" crystals and vacuum tube devices (called thermionic valves in British English). Today the most common diodes are made from ultrapure semiconductor materials such as silicon or germanium.

2.3 Resistor

A resistor is a two-terminal electrical or electronic component that resists an electric current by producing a voltage drop between its terminals in accordance with Ohm's law.

The electrical resistance is equal to the voltage drop across the resistor divided by the current that is flowing through the resistor. Resistors are used as part of electrical networks and electronic circuits.

In general, a resistor is used to create a known voltage-to-current ratio in an electric circuit. If the current in a circuit is known, then a resistor can be used to create a known potential difference proportional to that current. Conversely, if the potential difference between two points in a circuit is known, a resistor can be used to create a known current proportional to that difference.

Current-limiting. By placing a resistor in series with another component, such as a light-emitting diode, the current through that component is reduced to a known safe value.

An attenuator is a network of two or more resistors (a voltage divider) used to reduce the voltage of a signal.

A line terminator is a resistor at the end of a transmission line or daisy chain bus (such as in SCSI), designed to match impedance and hence minimize reflections of the signal.

All resistors dissipate heat. This is the principle behind electric heaters.

2.4 Capacitor

A capacitor is a device that stores energy in the electric field created between a pair of conductors on which equal magnitude but opposite sign electric charges have been placed. A capacitor is occasionally referred to using the older term condenser.

A capacitor consists of two electrodes, or plates, each of which stores an opposite charge. These two plates are conductive and are separated by an insulator or dielectric. The charge is stored at the surface of the plates, at the boundary with the dielectric. Because each plate stores an equal but opposite charge, the total charge in the capacitor is always zero. In the diagram below, the rotated molecules create an opposing electric field that partially cancels the field created by the plates, a process called dielectric polarization.

The capacitor's capacitance (C) is a measure of the amount of charge (Q) stored on each plate for a given potential difference or voltage (V) which appears between the plates:

In SI units, a capacitor has a capacitance of one farad when one coulomb of charge causes a potential difference of one volt across the plates. Since the farad is a very large unit, values of capacitors are usually expressed in microfarads (µF), nanofarads (nF) or picofarads (pF).

The capacitance is proportional to the surface area of the conducting plate and inversely proportional to the distance between the plates. It is also proportional to the permittivity of the dielectric (that is, non-conducting) substance that separates the plates.

The capacitance of a parallel-plate capacitor is given by:

where ε is the permittivity of the dielectric, A is the area of the plates and d is the spacing between them.

2.5 Relay

A relay is an electrically operated switch. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal.

All relays operate using the same basic principle. For example, 4 pin relay used. Relay have two circuit: A control circuit ( shown in GREEN ) and a load circuit ( Shown in RED ). The control circuit has a small control coil while the load circuit has switch. The coil controls the operation of the switch.

When no voltage is applied to pin 1, there is no current flow through the coil. No current means no magnetic field is developed, and the switch Is open. When voltage is supplied to pin 1, current flow though the coil creates the magnetic field needed to closed the switch allowing continuity between pin 2 and 4.

2.6 List of Component:

Transistor - BC 547

- C945

-Photo transistor

Diode -IN4148


Capacitor - 1000µF

- 10µF

- 1µF

- 220µF

- 100nF

IC - CA3140

- CD 4001

- UA741CN

Infrared Sensor

Switch push to ON

Relay 9Vdc

Fuse 3AMP

Motor 12Vdc, 20RPM

Chapter 3- Methodology of the project

3.1 Flow Chart












3.2 Schematic Diagram:

1. Infrared Sensor with relay diagram

The circuit of this Infrared (IR) detector circuit is a simple light relay which triggers when infrared light is applied to phototransistor. This device can be used in control system. When infrared light is OFF, transistor and relay are normally closed.

When IR diode is transmitting IR light photo-transistor opens and thus relay triggers because current starts flowing through Q1 transistor. Construction can easily be modified when circuit output is connected to microcontroller or other device. Sensitivity so the distance can be controlled by changing IR diode D1, using more sensitive phototransistor and adjusting R2 resistor.

2. Motor Control Circuit Diagram (Forward /Reverse)

The motor control circuit is has two inputs, via resistors R21 and R22. When a positive signal is applied to R21 transistor TR4 is turned 'on', and causes RELAY1 to switch off and RELAY2 to switch on.

Assuming that TR3 is turned off, the voltage at "B" will be positive and hence RELAY 1 will be on, and RELAY2 off. flow from the positive rail, through RELAY, to the motor and .

A similar sequence of events will occur if a positive signal is applied to R22,except that TR5 and TR8 will switch on, resulting in the motor rotating in the opposite direction. When the inputs at resistor R21 and R22 are both at around 0V, TR3 and TR4 will both be turned off, and all four power transistors will switch off, hence stopping the motor.

If a positive signal were to be applied to R21 and R22 at the same time, all four power transistors would turn on and a short circuit would occur. The diodes D8 and D9 should ensure that both outputs (i.e from pin 4 and pin 11 of IC4) can never be positive at the same time, making the situation impossible.

Indicator D16 is a bi-color l.e.d which glows red when the current flows in one direction, and green when the current is reversed. Two separates l.e.d.s could be employed if preferred. Capacitor C11 suppresses voltage spikes produced by the motor, and the four diodes D12 to D15 remove voltage spikes which may damage the transistors.

Current from the motor reversing circuit must pass trough resistor R27 on its way to 0V. If the motor stalls, the voltage across R27 will rise and this rise in voltage is fed through R25 to trigger the "current sense stop circuit" built around IC3.

When the voltage at the non-inverting input (pin 3 ) of IC3 rises above the voltage determined by the setting of preset VR4, the output pin 6 switches from 0V to positive. This causes an effect similar to pressing S1, the stop switch. Diode D3 prevents current flowing back to pin 6, if S1 is pressed whilst pin 6 is at 0v.

Capacitor C1 delays the stopping action a little, to allow the motor to start up initially. Once the motor has stopped, pin 6 switches back to about 0V.

Note that capacitor C1 determines the speed with which the circuit react to the stalling motor, the circuit must be sensitive enough to detect the fully wound curtains, but not be so sensitive that the motor cannot be started initially. Fine control is provided by preset VR4.

In practice VR4 controls the ease with which the curtains are brought to rest. Since opening requires more force than closing and the force required increase as the curtains open, VR4 actually controls how far the curtains are pulled open.

3.3 Schematic diagram layout on front of the PCB:

1. Infrared Sensor with Relay

2. Motor control (forward/ reverse)

3.4 Schematic diagram layout on the back of the PCB:

1. Infrared Sensor With Relay

2. Motor control (forward/ reverse)

PCB Fabrication:

PCB Drawing: PCB drawing is designed using Protel DXP 2005, this software can automatically convert schematic file to pcb automatically.

Film Printing: After PCB file is generated, use laser printer to print it on transparency.

PCB Cutting: Cut photo PCB size according to the film size.

PCB Photo Etching: Expose the photo PCB in photo etching kit for 8-10minutes.

PCB Developing: Wash the PCB using PCB developer (white powder) for 2 min.

Acid Etching: After PCB is developed, put it in Ferric Chloride liquid. Add in hot water (80C) and shake the water until you see unused part is 'washed' and only left only the tracks.

Alcohol Washing: Wash the PCB with alcohol to get rid off the green coating.

Drilling: Drill PCB after alcohol washing, use drill bit 0.8mm, 1.0mm and 1.2mm.

Soldering: Place all components on the PCB, use tape to stick all components tightly on the PCB and then solder the components using soldering iron and lead.

Chapter 4- Operation and Process

4.1 Introduction

This chapter explains a background and design of the system. This chapter also explain some circuit process.

On research and gain some information from website, started to construct a circuit for infrared sensor with relay and motor control system. This project is divided into few major parts.

4.2 Operation of the system:

Here is the step by step how the automatic rising and dropping toilet bowl lid. This will tell briefly how the system works.

1. User coming into toilet room

2. User walks near the toilet bowl

3. Infrared sensor detected user, Red light will be off

4. Signal will send to another circuit diagram, motor control system

5. Motor control system receive signal, forward signal will applied

6. 9V voltage will give to motor. Then motor will moving

7. Motor will stop working when user press stop or the lid move to the limit then auto- cutoff.

8. In motor control system have 3 buttons to press. That is forward, reverse and stop.

9. If user press stop, after they go away, the lid will automatically back to position.

4.3 Flow chart:

Infrared Sensor stand- by (red light ON)

User detected

Infrared Sensor detected (red light OFF)

Reverse signal applied, motor move reverse. Back to position

User finishes use, then walk away

Motor Stop moving

STOP button

Motor moving forward (Clockwise)

Forward signal applied (green light on circuit)

Signal send to Motor control system