Liquid level Alarm
Summary
Most of the time we face the problem of over flowing of tanks either underground or overhead; we forget to close taps which then leads to overflowing thus creating wastage of water. The floating plastic ball doesn’t indicate the full position of tank and also creates unnecessary pressure in the pipelines, when motor is used to fill up the tank.
This project with circuit demonstrates an electronic liquid level alarm which intimates us when tank gets full, thereby reducing chances of overflow.
The circuit of this project is based around the principle that water is a good conductor of electricity. One wire connected to Vcc (+9V) and is dipped in tank in such a way that it reaches the bottom of the tank. A second wire is placed inside the tank to indicate the full position of the tank. Find out how the circuit works following the principle of conduction.
Description
). When the tank is empty there is no input at base of T1 and it does not conducts, as a result point A becomes high. This voltage at point A is fed at base of T2 (BC 547), which biases it and hence T2 conducts which makes point B low. Point B is connected to reset pin of 555. When logic 0 is applied to reset pin of 555, there is no output.The output of 555 is connected to the input of another 555 whose output also becomes low due to same reason. The first 555IC operates at a low frequency and the second at a high frequency. The output of IC2 is fed into speaker. When tank becomes full, wire with resistor R1 receives some voltage due to conducting nature of water . This wire is connected to base of T1, as a result T1 starts conducting and point A comes at logic 0. This in turn forces the transistor T2 to go in the cut off state, thus making point B high. This high input is fed into reset pin of IC1 which starts giving output, this output is fed into reset pin of IC2 and hence IC2 also starts producing output pulses of high frequency. This is then fed into speaker through a coupling capacitor which blocks DC signals and allows AC signals and through a variable resistor to set volume of speaker .The speaker used is 8
, 0.5 watt.
Circuit Diagram
Components
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Resistor Resistor is a passive component used to control current in a circuit. Its resistance is given by the ratio of voltage applied across its terminals to the current passing through it. Thus a particular value of resistor, for fixed voltage, limits the current through it. They are omnipresent in electronic circuits. ... |
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Capacitor
Capacitor is a passive component used to store charge. The charge (q) stored in a capacitor is the product of its capacitance (C) value and the voltage (V) applied to it. Capacitors offer infinite reactance to zero frequency so they are used for blocking DC components or bypassing the AC signals. The capacitor undergoes through a recursive cycl... |
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Transistor BC547 BC547 is an NPN bi-polar junction transistor. A transistor, stands for transfer of resistance, is commonly used to amplify current. A small current at its base controls a larger current... |
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Speaker A loudspeaker (or "speaker") is a transducer that converts electrical energy into acoustical energy. When an electric signal is applied to the input pin of speaker, it generates sound waves. The other pin is connected to ground. A speaker is commonly used to produce sound in response to a sensor output. For example, in an... |
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555 Timer IC 555 is a very commonly used IC for generating accurate timing pulses. It is an 8pin timer IC and has mainly two modes of operation: monostable and astable. In monostable mode time delay of the pulses can be precisely controlled by an external resistor and a capacitor whereas in astable mode the frequency & duty cycle are controlled by two external resistors and a... |
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