A water level indicator is a simple yet effective solution to monitor and control water levels in tanks or reservoirs. In this blog, I will explain how to build a 3-tier water level indicator using only 3 transistors.
For this 3-tier water level indicator, we will use three transistors, each representing a different water level: low, medium, and high. When the water level reaches a certain point, the corresponding transistor turns on, activating an LED indicator.
Parts and Steps
Using multimeter, select 3 resistors of ~400Ω and 3 of 1K
Connect PNP Transistor in series with LED Diode and Resistor. Pay close attention to LEDs positive and negative side (Hint: small leg is negative)
Use color coding to make it easy to understand the circuit. For example: Use Red LED with Red wire for Low indicator.
Pour water very slowly and see different LEDs light up as water level increases
How does water turns LED ON
Transistor acts as a switch in this experiment, which is controlled by the water level. As the water level rises, a small amount of current flows to the base of the transistor. By setting the base voltage of a PNP transistor to lower than the emitter, the transistor turns ON and allows for current to flow from emitter to collector and thereby turning the LED ON!
Example Applications:
Industrial Processes: Water level indicators are used in industrial processes where precise control of water levels is necessary for efficient operation.
Home Automation: Water level indicators can be used in homes to monitor the water levels in overhead tanks, alerting us when they need to be refilled.
Agriculture: A similar system is used in agriculture to monitor the water levels in irrigation systems, ensuring that crops receive adequate water.
Aquariums: Similar systems are also used in aquariums to maintain optimal water levels for fish and other aquatic creatures.
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