12-12-2012, 05:23 PM
Water Level Indicator
Water Level Indicator.docx (Size: 382.85 KB / Downloads: 715)
Features of this circuit
• No microcontroller required.
• Only two 4011 NAND gates IC are used to generate the required signals to start and stop the motor automatically.
• There are 3 LEDs in the circuit. D1 LED indicates if water is touching sigLow sensor or not. Similarly, D2 LED indicates if water is touching sigHigh sensor or not. And D3 LED indicates if motor is turned on or not.
• When water level is below sigLow sensor, then motor is turned on. And when water level reaches sigHigh sensor then motor is automatically turned off. After this, even if water level drops below the sigHigh sensor, motor is not turned on, until water level drops below the sigLow sensor. This is achieved using the combinational logic of NAND gates.
Components
Different parts of the circuit are explained below.
Input Voltage: 12volt power supply is required.
Capacitors: The capacitors used in this circuit need to have a rating of at least 25v.
Q1 transistor: Any npn transistor will work here.
Water Sensors: Simple wires can be placed in the water tank. As the current required to pass through the wire is in micro amps. But if you want then you can place carbon rods at the end of wires which can be extracted from the 1.5v AA cell. These carbon rods should be thoroughly washed and then attach the wire to the carbon rod and then use some epoxy to hide the wire part.
Relay: A powerful relay should be used which must be able to handle all the current a water pump needs to work properly. In this circuit a 12v relay is used, but you can use 5v relay as well, by removing 7805 regulator and attaching 5v supply with the whole circuit.
How to simulate this circuit in Proteus
To simulate this circuit in Proteus, you can download the simulation from the 'Downloads' section below. After opening this simulation in Proteus, you can simulate all three conditions possible which are,
• Water level is below sigLow and sigHigh sensors.
• Water is touching only sigLow sensor.
• Water is touching both the sigLow and sigHigh sensors.
In the Figure 1 above, J1 connector is used to connect this circuit with the sensors present in the water tank. J1 connector has 3 pins and connections to these pins with the water tank are shown in the Figure 2. Ground wire is inserted at the bottom of the water tank. And sigLow wire is inserted at about 20% water level in the tank, while sigHigh wire is inserted at 100% water level in the tank.