Yesterday I built a tesla coil, using the plan from nuts and volts,
http://www.nutsvolts.com/PDF_Files/tesla.pdf I hooked up a 15KV transformer with a dimmer switch to control the input voltage. This particular model should put out between 4" and 6" sparks, but it only puts out a maximum of 1". I'm probably doing something wrong and don't know it. It doesn't matter if the input voltage is 50 volts or 120 volts, it still gives the same 1" sparks. Doesn't seem to matter how high the voltage is, if that helps to figure out what I'm doing wrong. If anyone is willing to help me figure out how to get more efficiency out of my coil, I'd be glad to take some pictures of it and email them. Thanks in advance for any help.
Davido Hyer