After a grand plan to control a bunch of twinkling LEDs in the fairy tree outside my house, I have decided to try a simpler approach.
The plan now is an analog circuit in which a photoresistor turns on a MOSFET at night, allowing current to flow through an LED. During the day, the photoresistor turns off the MOSFET, turning off the LED.
The main purpose of this is to make the batteries last longer. Using just an LED clipped directly to a CR2032 coin cell, I've been getting around 60 hours of operation.
There's a secondary goal of making the battery easier to replace by adding a battery clip and a PCB, so I don't have to untape and retape the LED for every new battery.
