The basic operation is essentially that of 2 separate photo sensor circuits in pairs. Each separate sensor circuit has a control pot to set it’s sensitivity for bright sunlight.
It is important to have a thorough understanding of the operation of the circuit in order to be successful in making the correct adjustments for acceptable operation. One must do the adjustments on a clear cloudless day. At the very least wait until the sun is between clouds.
CdS cells have a wide variance in the resistance they exhibit in bright sunlight. Generally the resistance is too low for this type of circuit. I have found that the CdS cells can be modified to have higher resistance by painting the cells with a black marker. I use a Sharpie black permanent marker. I paint this on all sides and edges. If you get too much on it can be removed with fingernail polish remover or acetone.
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