Dark Sensor using LDR on Breadboard

It spreads light in the dark and remains off in the light.

Components:

1) 2 NPN Transistors (Code no: BC547)

2) 1 LED

3) 1 LDR (Light Dependent Resistor)

4) 4 Resistors ( 330 ohms, 470 ohms, 1k ohms, 4.7k ohms)

5) 9 volts battery

Circuit Diagram:

Schematic Diagram:

Video:

Dark Sensor using LDR On Breadboard by FunnyVideos123

Water Level Indicator on Breadboard

It indicates the water level of tank just before the over flow.

Components:

1) 3 LED's

2) 4, 100 Ohms Resistors

3) 4 NPN Trasistors (Code: BC547)

4) 1 Buzzer

5) 9 Volts Battery

Circuit Diagram:

Schematic Diagram:

Video: