A water level indicator/controller circuit using the ULN2803 Darlington transistor Array IC can help you monitor water levels in a container.
Hardware Components
To build this project, you’ll need the following components:
- ULN2803 Darlington transistor IC: This IC contains eight NPN Darlington-connected transistors with common clamp diodes for switching high-power loads.
- LEDs (RED): Eight 5mm LEDs to represent different water levels.
- Resistors: One 10KΩ resistor and one 560Ω resistor.
- DC Power Supply: 12V DC power source.
- Battery Clips for power supply connection.
- Connecting Wires
Circuit Diagram
The heart of this circuit is the ULN2803 IC. Here’s how it works:
- Connect the base terminals of all transistors (from PIN 1 to PIN 8, labeled as 1B to 8B) as individual probes for each water level. (In the attached circuit diagram, only one probe connection is used. Similar way, you can connect upto 8 probes. Adding each probes will make the circuit more complex. You will have to redesign the circuit and power requirements).
- The positive rail serves as the probe, going through the container or reservoir.
- When the water level reaches the probe, it creates electrical connectivity between the positive rail and the probe, causing the associated LED to light up or relay to operate.
- The operating voltage of the circuit is 12V DC.
Applications
This water level indicator circuit can be used in various scenarios:
- Factories, manufacturing complexes, apartments, and homes.
- Wide-scale industrial processes such as cooling tower water level control, life station switches, tsunami warning systems, irrigation control, fuel tank level gauging, and sump pumps1.