INDEX

Sr No. Name of topic Page no

1 Introduction 1

2 Functions of the materials

2

3 Transistor BC 548 Specification Datasheet

3

4 Working 4-5

5 Circuit Diagram 6

6 Scope 7

7 Materials 8

8 9

1

INTRODUCTION

This circuit not only indicates the amount of water present in the overhead tank  but also gives an alarm when the tank is full. When the water is empty the wires in the tank are open circuited and the 220ohm resistors pulls the switch low hence opening the switch and LEDs are OFF. As the water starts filling up, first the wire in the tank connected to S1 and the +supply are shorted by water. This closes the switch S1 and turns the LED1 ON.As the water continues to fill the tank, the LEDs2, 3 and 4 lights up gradually. The no. of levels of indication can be increased as per your requirement. When the water is full, the base of the transistor BC548 is pulled high by the water and this saturates the transistor, turning the buzzer ON.

2

Functions of the materials:

1. Resistors:   they limit the current and provide only the required

biasing to the vital parts like transistors.

2. Transistors:   they amplify the current to provide right amount of

current to the led's to operate.

3. Diode:   it allows the current to pass in one direction only.

4. Led bulbs:   to indicate different water levels.

5. Connecting wires: to allow the passage of current.

6. 9v battery: to provide required voltage for the led's and prevent

hazards related to current.

3

Transistor BC 548

The BC548 is a general purpose epitaxial silicon NPN bipolar junction transistor found commonly in European electronic equipment.

The part number is assigned by Pro Electron, which allows many manufacturers to offer electrically and physically interchangeable parts under one identification. The BC548 is commonly available in European Union countries. It is often the first type of bipolar transistor young hobbyist’s encounter, and is often featured in circuit diagrams and designs published in hobby electronics magazines.

The pinout for the TO-92 package has pin 1 attached to the collector, pin 2 connected to the base, and pin 3 connected to the emitter.

SPECIFICATION

Devices registered to this Pro Electron number must have minimum performance characteristics.

Breakdown voltage, with base open VCBO = 30 V Rated collector current IC = 100 mA Rated total power dissipation Ptotal = 500 mW Transition frequency (gain-bandwidth product) ft =

300 MHz

4

Working:

Wires of different lengths but of same material are tightened by the nuts. Each wire is connected to a particular led. When water is added in the bucket, the first led to glow is the one whose wire is longest. The second led glows when water makes contact with the second longest wire. When a particular wire makes contact with water it will be connected to wire “n” through water: establishing a negative voltage across the base of transistor. This results in the flow of current and hence the led’s glow.

Soldering- Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a relatively low melting point.

Soft solderingis characterized by the melting point of the filler metal, which is below 400 °C (752 °F). The filler metal used in the process is calledsolder . Soldering is distinguished from brazing by use of a lower melting-temperature filler metal; it is distinguished from welding by the base metals not being melted during the joining process. In a soldering process, heat is applied to the parts to be joined, causing the solder to melt and be drawn into the joint by capillary action and to bond to the materials to be joined by wetting action. After the metal cools, the resulting joints are not as strong as the base metal, but have adequate strength, electrical conductivity, and water-tightness for many uses. Soldering is an ancient technique mentioned in the Bible and there is evidence that it was employed up to 5000 years ago in Mesopotamia

5

Soldering filler materials are available in many different alloys for differing applications. In electronics assembly, the eutectic alloy of

63% tin and 37% lead (or 60/40, which is almost identical in

performance to the eutectic) has been the alloy of choice. Other alloys are used for plumbing, mechanical assembly, and other applications. In high-temperature metal joining processes (welding, brazing and soldering), the primary purpose of flux is to prevent oxidation of the base and filler materials. Tin-lead solder, for example, attaches very well to copper, but poorly to the various oxides of copper, which form quickly at soldering temperatures. Flux is a substance which isnearly inert at room temperature, but which becomes strongly reducing at elevated temperatures, preventing the formation of metal oxides. Secondarily, flux acts as a wetting agent in the soldering process,

6

reducing the surface tension of the molten solder and causing it to better wet out the parts to be joined.

CIRCUIT DIAGRAM

7

SCOPE

This circuit not only indicates the amount of water present in the over head tank but also gives an alarm when the tank is full. This worthy device starts ringing as soon as the water tank becomes full. It helps to check overflow and wastage of water by warning the customer when the tank is about to brim. The system provides visual water level indication with audio alarms at desired levels. It also provides automatic control of pumps at a remote location.

• Now no need to go on the roof to look the water level.

•It shows the water level in your room like 1/4 tank, 1/2 tank, 3/4 tank and full tank.

•Alarm starts ringing as soon as tank becomes full.

•Suitable for every tank.

8

Materials

1. Transistor BC 548

2. 6 Resistor 220 ohm

3. 3 colour LED

4. Buzzer

5. Battery Cap

6. PCB board

7. Wire

8. Soldering wire

9. 9V Battery

10. Soldier

9

Bibliography

50 Electronic Projects, Author: MR A.K MAINI

Mini & Major Electronics Projects,Author: MR S.A KHAN,

Mahal

Electronic Devices & Circuits,Author : S. Salivahanans, N

Kumar, Publisher : TATA MCGRAW HIL

Electronic Devices & Circuits I, Author : J.S. Katre

Electronics Devices & Circuits - II, Author : Katre J. S

www.philohome.com/sensors/gp2d12/gp2d12-datasheets/

bc548.pd

www.alldatasheet.com/datasheet-pdf/pdf/50731/.../BC548.html?

www.instructables.com/id/Water-Level-Indicator

www.electronicsforu.com/efylinux/circuit/cir105.htm

10