Darkness Sensor Using OpAmp

I have made a darkness sensor circuit using lots of different things like 555-timer ic, transistor and OpAmp

but the OpAmp circuit most reliable circuit.

1 L.D.R(photoresistor)

2 any OpAmp(741)

3 higher value resistor 100k(approx) I'm using 150k ohm

4 lower value resistor 1k ohm

5 10k potentiometer

current limiting resistor (220 ohms)

to buy all product use this link click here and use "SAVE5" coupon at checkout to get 5% discount

1. Construct voltage divider using a resistor(higher value)(100K) and L.D.R

2. Measure the voltage across the L.D.R according to your power supply and note it down.

3.Construct another voltage divider using a resistor(lower value)(1K) and potentiometer(10k).

4. Measure the voltage across the potentiometer and set it to the voltage(noted).

1. Connect Vref(second voltage divider) to the inverting terminal of OpAmp.

2. Connect the first voltage divider node to the non-inverting terminal of OpAmp.

3 .Connect V(+) to Vcc and v(-) to GND.

4. Connect the output terminal to the anode of led and cathode to GND via a 220-ohm resistor.

my YouTube channel