Dark/Light sensor using transistor

Dark light sensor
Automatic dark detector senses darkness. As the light level decreases and LDR meets the maximum threshold resistance, the circuit automatically switches on the LED D1. 

Dark light sensor

Dark sensor with variable resistor:
Dark light sensor

A dark detector can be made using a variable resistor. The sensitivity of the circuit can be adjusted with a variable resistor.

High resistance-> more darkness to switch on the LED.

Low resistance-> less darkness to switch on the LED.

Automatic Light detector using variable resistor

A light detector senses light. As the light level increases and LDR meets the lowest threshold resistance, the circuit automatically turns on the LED D1. We can adjust the sensitivity using the preset VR1-10K.

LESS RESISTANCE(VR1)-> LESS DARKNESS TO SWITCH OFF THE LED

HIGH RESISTANCE(VR1)-> MORE DARKNESS TO SWITCH OFF THE LED
Dark light sensor

Just swap the resistor and LDR to convert a dark sensor to a light sensor

Dark light sensor

Dark light sensor

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