I am looking for an example of a day-light sensing LED light, similar to https://www.evilmadscientist.com/2007/a-simple-and-cheap-dark-detecting-led-circuit/ but instead of turning on when dark, I want it to turn on when light. Could anyone point me to an example, or lead me down the right path?
closed as too broad by Andy aka, brhans, Voltage Spike, Dwayne Reid, Dmitry Grigoryev Jun 18 '18 at 8:11
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You have two simple possibilities:
- Switch the position of the resistor and the phototransistor. This way the resistor will pull down the base of the NPN when it's dark and the phototransistor will pull it up when it detects light.
- Use a PNP instead of the NPN transistor and keep the resistor and the phototransistor where they are.