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    • #9127

        Hi all,

        When looking in the manuals, I noticed the absence of relay circuits controlled by transistors.
        Time to change that !
        Here is a very sensitive light switch that reacts to waving your hand above the LDR module.
        After building the circuit, place it in direct sunlight.
        Set the potentiometer so that the lamp just turns on.
        When you shade the LDR, the lamp goes out.

        We use here a so called darlington transistor pair which has a high amplification factor.
        You also notice that we use the transistor module with the 680k resistor.

        Many greetings

        Here’s the diagram and setup :

        Legacy darlington LDR circuit

      • #9129

          Hi Frank,
          Thanks so much for this cool circuit.  Excellent design elements!  Well done.

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