28-07-2014, 12:54 PM
The Working Principle
Putting the circuit in a box.docx (Size: 1.06 MB / Downloads: 13)
Introduction
Today we are going to talk about a very useful project that we had taken up. It is called the Water Level Indicator. Nowadays everybody has overhead tank at their homes. But everyone who has a water tank above knows the kind of problems that they face. Firstly there is no system to track the water in the tank. Then there come a secondary problem that is when their water pump is started they have no idea when it gets filled up and sometimes there are situation where the pump keeps on pumping water to the tank and the water starts spilling out from the tank. There is wastage of energy as well as wastage of water.This project that we had taken up is the result of long hours of research of work at the Internet as well as long hours of thinking. We had made various versions of the projects earlier but at last we came up with this final product. We bet this has been tested and we can now firmly say that the model would work flawlessly without any complains for years. We are saying this as we have installed this models to various houses in my neighborhood and all are working fine without any maintenance. And indeed this model is admired by all who uses it.The house where we live in has an overhead tank which is about 30 feet from the ground level. we was getting bored going up the rooftop to check whether the tank has filled or the water level was below to start the pump.we had to do this again and again. Then I sought for a solution. We always used to think of the possibilities of how can this problem be tackled in an electronic way. After years of research and by trial and error, we found one and wanted to put whatever we have done out here so that it may be helpful to someone who has a overhead water tank at their homes. Your luggage, burglars breaking into your house etc. The alarms goes ON when a thin wire, usually as thin as a hair is broken.The circuit is straightforward. It uses a 555 IC wired as an astable multivibrator to produce a tone of frequency of about 1kHz which gives out a shrill noise to scare away the burglar. The wire used to set off the alarm can be made of a thin copper wire like SWG 36 or higher.You can even use single strands of copper form a power cable.The circuit operates on a wide range of voltages from 5V to 15V.speaker and the circuit could be housed inside a tin can with holes drilled on the speaker side for the sound to come out.
The Working Principle
Basically the unit is made up of various sensors acting as a switch. Let me explain in a simple way. What happens is when you turn on you water pump, the water starts to get pumped from your underground reservoir or from your underground water supply from the pipes to your water tank. In the tank there is a set of sensors ( to be precise there are 7 sensors), in the water tank. Just think them as a switch, as the work of the sensor will be to connect a circuit. I will explain in details in my instructables. So the water starts to get filled in the tank and when the water level in the tank starts to rise up, what happens is that the sensors that is installed in the tank starts to get activated one by one indicating the water level in the tank. And finally when it reaches to its top most sensor, there will be a visual display as well as a sound from the unit indicating that the water has filled in the tank and one can be alerted that the tank has been filled up and the water pump has to be switched off saving the electricity bill as well as over flow of water from the tank.
The Circuit
It has numerous transistors acting as a switch and the switch gets activated when the sensors tell them to. The heart of the circuit is the transistors BC 547. There are total 7 transistors in the circuit and each one will be sensing the level of water present in the overhead water tank. There is one extra power LED without a transistor and that is because this Red LED will be telling us two things. Firstly when you power the unit it will be monitoring the power present in the unit and secondly it is also the indicator telling you that there is no water at all present in the tank. As because the water level is below the No. 1 (as shown in the circuit) sensor, no LED's will be lighting up, but only for the one Red LED. Therefore when you switch on your unit if you see only one Red LED lighting up then you know that the is no water present in the tank and therefore you should make you water pump on.Then as shown in the figure i have given all the LED's in various color. Starting from the beginning is -
• Red LED (Indicating no water in the tank as none of the sensors are getting contact with the water)
• Red LED ( Level 1, indication very low water in the tank )
• Yellow LED (Level 2, indication of low water)
• Yellow LED (Level 3, indication of 1/4 of water in the tank)
• Green LED (Level 4, indication of half of water in the tank)
• Green LED (Level 5, indication of more than half of water)
• Green LED (Level 6, indication of nearing filling up the tank)
• Blue LED (Level 7, Full indication of tank and buzzer comes on)
Now as the water starts to rise up the sensors starts to get in contact with the water and the transistors are activated and there is a flow of current in the transistors making the LED's light up. Here in between the transistor and the LED there is a current limiting resistor 470 ohms, the job of the resistor is to checks that the LED does not get over voltage and destroy the LED. The transistor is biased by a 470K resistor with the ground and the sensing part is taken from the collector with a 33 ohms resistor going directly to the tank. As i have shown in the diagram the
Fig:-3.1-Circuit diagram of water level indicator with alarm
signals are drawn in the Green color. There by you can follow the LED's as they light up from Red to Yellow and then Green and finally to Blue making a sound.
. Putting the circuit in a box
Now time to put the compiled circuit in a small box. Here we chose a Junction box that are used in electrical wiring. It was a perfect box for this project. Now the tricky part is making holes in the plastic junction box so that LED can easily slip through the holes, also the spacing between the LED's should be proportionate. First take the box and draw the outline in the face of the box. First for the switch you should make a marking at the bottom right hand side. Then mark the points for the LED's. As told earlier it should be proportionate. Now unbend a paper clip and heat it with a soldering iron and make holes to the marked points as shown in the figure. Then cut the plastic board for the power switch. After the cut is made file at the edges so that the cut is smooth and the switch can easily fit to into the cut. Fit in the Power Switch. Time for adding the LED's to the panel. Let's start by adding the Red LED from the bottom end. Then to the Yellow and Green and finally Blue. This LED's should be then be soldered to the PCB as shown in the circuit diagram. For me what we did was soldered directly to the PCB below the front panel, as it gave a solid base for the LED's. Now fix the buzzer just beside the PCB and give the connection from the circuit board. Then also fix the Power supply at the box with the help of nuts holding the transformer firmly to the box. For making a junction of the sensors you can use a cable connector, we used from a used TV circuit board as shown. This connector was actually connecting some wires with the television PCB to the CRT (Cathode Ray Tube of the TV), therefore i decided to use this as it had many pins. I then cut it from the PCB and numbered it from 1 going up till 8. You will notice that there were two pins extra, so i made this two pins connect together and made a common point for the sensor going to the tank. The rest of the pins starting from Pin 1 going up till 7 will be for the sensing part which will also be connected to the sensors of the water tank.