A Simple Liquid Level Indicator With a Single IC
This project, designed by Hulk, demonstrates how to create a liquid level indicator for a water tank using a ULN2003 Darlington transistor array and some basic components. The ULN2003 contains seven transistors, allowing you to easily switch seven LEDs to visually indicate water levels.
Here’s how it works:
- Electrodes are placed at different heights inside the water tank.
- A positive electrode is connected to a 12V supply.
- As water rises in the tank, it touches each electrode, which completes a circuit between the base of a transistor in the ULN2003 and the positive electrode.
- This triggers the corresponding transistor to turn on, lighting up an associated LED.
- Different colored LEDs—green, yellow, and red—provide a clear visual of the water level, with green indicating lower levels, yellow indicating mid-range, and red showing high water levels.
This simple yet effective design provides a clear, seven-level indicator for water levels, making it especially useful for large or opaque tanks where direct visual confirmation is not possible.
Read more: A Simple Liquid Level Indicator With a Single IC