20-09-2017, 09:22 AM
Here is a simple water level indicator for the top tanks that uses three LEDs (LED1, LED2 and LED3) to indicate minimum, medium and maximum water levels in the tank.
The sensor probes comprise A, B, C and D, where A is the common probe and B, C and D are intended to detect minimum, medium and maximum levels, respectively. When the water in the tank touches sensors A and B, a small current flows from A to B through the water and to the base of transistor T1 through resistor R1. As a result, the transistors T1 drive, causing the LED1 to illuminate. Similarly, when water touches sensor C, LED2 illuminates to indicate that the water has reached the mean level. Finally, when the water touches sensor D, LED3 lights to indicate the maximum water level. Therefore, the three LEDs glow when the tank is full. In this phase, the motor must be switched off manually.
Water Level Indicator Circuit
The circuit can be easily mounted on a general purpose PCB and enclosed in a wooden box. The three LEDs must be mounted on the front panel of the box with a space of about 4 cm between them. Short lengths of four 18 SWG copper cables can be used for sensor probes. For the common sensor A, a bare copper wire of 18 SWG should be used. For sensors B, C and D, three single-core PVC wires should be used, with their insulation removed one centimeter long at the ends. The four cables can be tied about 12.5 mm in diameter. PVC pipe with nylon thread at different heights without touching (not shown in the figure).
The sensor probes must be kept in the tank vertically and connected to the main circuit using four flexible PVC wires of different colours.
The circuit is powered by a battery eliminator or a 6V battery and is kept close to the motor unit. The intensity of the circuit, when all LEDs glow, is up to 50 mA, which is less than the current of a 6V lamp.
Water Level Indicator Circuit
The circuit can be easily mounted on a general purpose PCB and enclosed in a wooden box. The three LEDs must be mounted on the front panel of the box with a space of about 4 cm between them. Short lengths of four 18 SWG copper cables can be used for sensor probes. For the common sensor A, a bare copper wire of 18 SWG should be used. For sensors B, C and D, three single-core PVC wires should be used, with their insulation removed one centimeter long at the ends. The four cables can be tied about 12.5 mm in diameter. PVC pipe with nylon thread at different heights without touching (not shown in the figure).
The sensor probes must be kept in the tank vertically and connected to the main circuit using four flexible PVC wires of different colours.
The circuit is powered by a battery eliminator or a 6V battery and is kept close to the motor unit. The intensity of the circuit, when all LEDs glow, is up to 50 mA, which is less than the current of a 6V lamp.