07-11-2012, 03:34 PM
Measuring techniques for level measurement
The circuit 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. This wire is connected to transistor T1 (BC 547) via resistance R1 (12k ). 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 capacitor to filter noise and through a variable resistor to set volume of speaker .The speaker used is 8 , 0.5 watt.
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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...
Measuring techniques for level measurement
In continuous level measurement, the level of a medium in a tank or silo is detected and converted into an electronic signal. The level signal is either displayed directly on site or incorporated into a process control or management system. The measured media are liquids, pastes, powders or bulk solids.
Typical applications for continuous level measurement are process tanks, storage tanks or silos in the process industry.
The different industries place very specific requirements on the measurement technology they use. Taking the properties of the medium as well as the individual process conditions into consideration, VEGA provides a level sensor perfectly adapted to each measuring point.
With the "finder" you can determine the right sensor for your application quickly and easily.