Intro: Powering Automatically a FM-Radio With a Simply Ambient Light Switching System
The goal of this gadget is to turn on , your bathroom FM radio , when your
powerup the light. Very easy to build, look the shem bellow.
The voltage input is +9/12v don't care, the LDR is a simple photresistor, http://en.wikipedia.org/wiki/Photoresistor
You can tune the sensitivity with a adjustable resistor.