Hello, I'm working on a little experiment where I want to use a phototransistor or photodiode to adjust the brightness of a series of LED lightbulbs. I want to use actual lightbulbs (40 W socket with 6W power). I also want to use DC power if possible. What would be a good way to go about this? I basically want it to measure the amount of light outside and compensate by brightening the bulbs if it is dark outside, and dimming the bulbs if it is bright outside. Thank you so much for any help.

 

There is a circuit in Forrest M. Mims: "Timer, Op Amp & Optoelectronic Circuits & Projects" book on page 66 called a Light-Sensitive Oscillator and it increases the frequency as the light level increases. So swapping the inputs over would make the output frequency decrease as the light level increase. Now all you need to do is figure a way of interfacing your lights to the output instead of the piezo speaker, maybe use a power FET?