Here is a VLF receiver tuned to 300 kHz designed to detect the crackle of approaching lightning. A bright lamp flashes in sychrony with the lightning bolts indicating the proximity and intensity of the storm.
http://www.electronics-lab.com/projects/science/001/
Llight operated switches are not new ideas, but neither are they the easiest items to purchase ready-made. Originally, this unit was built to switch on the author's outside Christmas lights when it became dark. No doubt readers will have other uses in mind. One such might be as a security porch light controller.
http://www.web-ee.com/Electronic-Projects/projects/light_op_switch/index.htm
This page shows three circuits for using the 555 timer IC as a photocell controlled train detector. The circuit is shown driving light emitting diodes but any load of less than 200 milliamps could be used.
http://home.cogeco.ca/~rpaisley4/xComp555photo.html
http://www.uoguelph.ca/~antoon/circ/sensor2.htm
A VLF receiver tuned to 300 kHz designed to detect the crackle of approaching lightning. A bright lamp flashes in synchrony with the lightning bolts indicating the proximity and intensity of the storm.
http://www.techlib.com/electronics/lightning.html