LM741
light/dark sensor with relay
The relay will be closed only
when "NO light falls on LDR1", however, in testing this circuit it
worked very well when the potentiometer (P1) is adjusted to a preset
level of light intensity.
By swapping the positions of the 10K
resistor (R1) and the LDR (LDR1), the relay will be closed when the
LDR is under light.
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Shopping List
1 x LM741 OP Amp
1 x LDR
2 x 470R 1/4W Resistor
2 x 10K 1/4W Resistor
1 x 1K 1/4W Resistor
1 x 1N4001 Rectifier Diode
1 x 10K Potentiometer
1 x 220uF Electrolytic capacitor
1 x 12V Relay
1 x General Purpose NPN transistor
(200mA+)
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