Water level indicator

Ic 7404

Ic 7408

Ic 7432

Transistor 547

Buzzers

breadboard

9v battery 

Demo video - https://youtu.be/0Ldwbbf4R9Y?si=nO055cwyOtICQe0a

Context of water level indicator circuit

The image and video provided describe a Water Level Indicator circuit. This system is designed to detect the water level in a tank and provide visual and audible feedback using LEDs and a buzzer.

Circuit Overview

Based on the image and the video:

 * Power Supply: The circuit is powered by a 5V DC source (V1) or a 9V battery as seen in the video. [00:05]

 * Sensors (Probes): The circuit uses four "switches" (Empty, Half, Full, and Overflow) which represent probes placed at different heights in a water tank. When water touches a probe, it completes a path to the base of the corresponding transistor.

 * Transistors (BC547A): There are four NPN transistors (Q1 to Q4). These act as electronic switches.

   * When water connects the positive supply to a probe, a small current flows through the 220$\Omega$ resistor (R1, R4, R6, R8) into the transistor's base, turning it ON. [00:34]

 * NOT Gates (7404 IC): The collectors of the transistors are connected to the inputs of NOT gates (U1 to U4).

   * When a transistor is OFF, the input to the NOT gate is HIGH (via pull-up resistors R2, R3, R5, R7), so the output is LOW (LED is off).

   * When a transistor turns ON, it pulls the input of the NOT gate LOW, making the output HIGH, which turns on the respective LED.

 * Visual Indicators (LEDs):

   * Yellow (Low): Indicates the tank is at the lowest monitored level.

   * Orange (Half): Indicates the tank is half-full.

   * Green (Full): Indicates the tank is full.

   * Blue (X1/Overflow): Indicates the tank is overflowing. [00:43]

 * Buzzer: Although the schematic doesn't explicitly show it, the video mentions and demonstrates a buzzer that sounds when the "Full" or "Overflow" level is reached, acting as an alarm. [00:07]

How it works

 * Tank Empty: All probes are open; all transistors are OFF; all LEDs are OFF.

 * Water at Low Level: The "Empty_Switch" probe is submerged. Q1 turns ON, U1 output goes HIGH, and the Yellow LED lights up.

 * Water at Half Level: The "Half_Switch" probe is reached. Q2 turns ON, and the Orange LED also lights up.

 * Water at Full/Overflow: Subsequent probes trigger the Green and Blue LEDs, and usually, the alarm/buzzer is activated to signal the user to turn off the water pump. [01:21]

Video Reference

The video you shared demonstrates this circuit built on a breadboard, showing the LEDs lighting up sequentially as the water level rises in the plastic bottle. [00:15]

Video Link: Water level indicator alarm

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