30-08-2017, 03:43 PM
Here is a simple water level indicator for the top tanks that uses three LEDs (LED1, LED2 and LED3) to indicate the minimum, medium and maximum water level 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 the sensor wires A and B, a small current passes from A to B through the water and to the base of the transistor T1 through the resistor R1. As a result, transistor T1 leads, causing LED1 to illuminate. Similarly, when the water touches sensor C, LED2 illuminates to indicate that the water has reached the middle level. Finally, when the water touches sensor D, LED3 lights to indicate the maximum water level. Therefore, all three LEDs glow when the tank is full. In this phase, the motor must be switched off manually.
The circuit can be easily mounted on a general 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 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 to the ends. All four wires can be attached around a diameter of 12.5mm. PVC pipe with nylon thread at different heights, without touching (not shown in the figure).
The sensor probes should be kept in the tank vertically and connected to the main circuit using four flexible PVC wires of different colors.
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.
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 the sensor wires A and B, a small current passes from A to B through the water and to the base of the transistor T1 through the resistor R1. As a result, transistor T1 leads, causing LED1 to illuminate. Similarly, when the water touches sensor C, LED2 illuminates to indicate that the water has reached the middle level. Finally, when the water touches sensor D, LED3 lights to indicate the maximum water level. Therefore, all three LEDs glow when the tank is full. In this phase, the motor must be switched off manually.
The circuit can be easily mounted on a general 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 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 to the ends. All four wires can be attached around a diameter of 12.5mm. PVC pipe with nylon thread at different heights, without touching (not shown in the figure).
The sensor probes should be kept in the tank vertically and connected to the main circuit using four flexible PVC wires of different colors.
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.