This document describes a water level indicator circuit project created by three students. The circuit uses transistors, resistors, LEDs, and a transformer to indicate water levels. When the brass strip touches water, it provides current to the transistor base, forward biasing the base-emitter and base-collector junctions. This allows collector current to flow and the LED to glow, signaling that the water has reached that level. The circuit leverages the transistor's ability to act as a switch in either cutoff or saturation mode.

1. ELECTRON DEVICES MINI
PROJECT
WATER LEVEL INDICATOR
BY:-
L RAGHAV SAI
M VENKAT SAI
SIVA REDDY

2. COMPONENTS REQUIRED
• TRANSISTORS(2N222)
• RESISTORS(22K,2.2K)
• LEDS(3)
• AC TRANSFORMER

3. CIRCUIT DIAGRAM

4. WORKING
• Transistor acting as a switch is the basic
application of this experiment.
• The areas for transistors to act as a switch are in
its cut off region (off state) and saturation region
(on state).
• In cut off region the input and base are grounded.
• Base emitter junction is reverse biased and base
collector is also reverse biased.
• No collector current flows.

5. • In saturation region input and base are given
some voltage.
• Base emitter junction is forward biased and
base collector is also forward biased.
• When the BRASS strip touches the water level
the base gets the current and the led glows up
and the water level is indicated.

6. THE END