I have created a homemade lightbulb as part of a history project and am wondering how to power it in a manner that is safe enough for school.
The lightbulb consists of a piece of .9 mechanical pencil graphite as a carbon filament in a sealed container (http://www.instructables.com/id/Homemade-Lightbulb/?ALLSTEPS)
I currently have a 12 volt drill battery that successfully powers the bulb to an adequate level for a short time before the alligator clips heat up too much.
I also have a step-down transformer I pulled from somewhere that (according to my measurements) steps down the 120v wall power to two secondary windings that each output 12 volts.
After some research I found out that shorting the secondary coil (which is basically what happens when I connect the light) creates lots of heat and can/should trip a circuit breaker on the primary side. So in other words inadequate for school.
My question is how I can power this lightbulb with minimal heat generated outside the jar in which it is contained. the project is due this Friday and I could turn it in as-is but I'm just trying to optimize it so it's safer. My theory of creating another bulb to increase the resistance wouldn't work due to time constraints
I'm competent with basic electrical engineering tools and terms