Water Level Indication Using Combination of Three NPN Transistors

Water Level Indication Circuit consists of breadboard, NPN transistors, LED’s, resistors, 9V battery and a tank made from transparent disposable 500 ml drinking water bottle. The details of project components are:

NPN Transistors: Project deployed three NPN transistors. The three different kinds of transistors used are: NPN 2N2222A, 2N3904 and BC547A.

LED Indicator: Project deployed four LED’s. One Red LED will blink and indicate the status of whether the battery is connected to the circuit board or not. Three different coloured LED’s shows level such as LOW as Red, MEDIUM as Green and High as Blue.

Resistors: Project deployed four resistors of value 470 ohm for LED’s and three 120 ohm resistors were deployed at the base of transistor.

Circuit Wires: Five coloured wires are used where Green shows Medium level connection; blue shows indication for Ground as well as High Level, red shows indication for power as well as Low Level and grey wire is used to ground the LED.

Step 1: Acquire Necessary Electronic Components

• BC547A - Qty(1) https://www.sparkfun.com/products/8928
• 2222A - Qty(1) https://www.sparkfun.com/products/12852
• 2N3904 - Qty(1) https://www.sparkfun.com/products/521
• Breadboard - Qty(1) https://www.sparkfun.com/products/9567
• LED's - Qty(5)
• Resistor - 120 Ohm (Qty - 5)
• Resistor - 470 Ohm (Qty-5)

Step 2: Prepare Circuit Diagram

Step 3: Breadboard & Wiring

Step 4: Wire Tank

Step 5: Project Powered With Battery (Red LED Indication Shows Its ON)

Step 6: Water Low Level (Red Indication)

Step 7: Water Medium Level Indication (Green LED)

Step 8: Water High Level Indication (Blue LED)