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Simple water level alarm circuit

2015-01-08 20:01  
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The article describes the water level alarm circuit. The circuit is very simple, very helpful. If you understand this principle is not very thorough, it is recommended to understand this circuit is an important component: 78L05 . This circuit will trigger with any fluid resistance at 900 k maximum spacing between the probes. Let me explain further. Circuit using 4050 b CMOS hex buffer working on a 5-volt power supply. All gates are biased a 10 m resistor connected between ground and buffer input. "Normal" probe above the top of the probe connected to the probe 1 in the figure above positive 5 volt supply. If the probe 1 is spaced 1 cm away from the common probe and tap water at 25 ° C between the detection probe (20 k resistor) then the top division is activated and LED 1 will light. Similarly, if the probe 2 at 2 cm from the detector detects a common water, resulting in two of the lamp and so on. Switch 1 is used to select the output hex buffer will trigger audio oscillator consists Gates CMOS 4011 b IC. In the circuit, seven lines necessary investigations I reccommend using the 8-way computer cable. The first two wires may be doubled, as a general probe line. Each subsequent line may be cut to the desired length, if you need a few millimeters may be deprived of the insulation back, although open to "cut off" line-side should be sufficient as a probe. Fluid and distance probe 6 and the general probe line must be less than 900 k. This is because any voltage below 0.5 volts in the CMOS integrated circuit is logic 0. A quick check of potential use 900 k resistor divider formed with 10 m resistor at the input proves this point: 5 times (0.9 / (0.9 10) = 0.41 volts and this voltage is below 0.5 volts is interpreted as a logic 0 and the LED will light if the measured water at 25 ° C and then the distance between the top of the probe and common may be 45 cm for other temperatures and fluids, it is recommended to use an ohmmeter first when the probe ordinary the probe must be placed a minimum probe, with the rise of the water level, it first through the probe 1, then 2, and finally the probe 6.

water level alarm



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