Stoneridge Engineering Home |
Tesla Coil Help
Posted by Ian on 5/31/2007, 4:52 pm We have recently built a high voltage Tesla coil for a graduating project for our high school, but we're having some problems. My friends and I were hoping that anyone might be able to help us troubleshoot. Sincerely,
|
Re: Tesla Coil Help
Posted by Bert Hickman on 5/31/2007, 11:48 pm, in reply to "Tesla Coil Help" You might also try reducing the number of plates used on your tank cap since a 15/30 NST will optimally drive a tank cap that's about 8 - 12 nF when used with a static spark gap. When the tank cap is too large for the NST, the NST doesn't have sufficient current to charge the tank cap up to the point where the spark gap will fire on every half cycle of the incoming AC waveform. Try not to reduce the capacitance to less than about 8 nF. Using at least 8 nF reduces the possibility of accidentally overvolting your NST (from 60 Hz resonance effects between the NST and your tank cap). The other possibility is that your tank cap may have developed a high voltage short. If this is the case, the cap will measure OK at low voltages, but will internally arc over when high voltage is applied. This will also prevent the spark gap from firing. Is your tank cap oil immersed? Oil immersion is essential to keep corona from damaging (and rapidly destroying) the polymer dielectric, particularly at the foil edges. Again, good luck! Bert
|
Re: Tesla Coil Help
Posted by Bert Hickman on 5/31/2007, 6:00 pm, in reply to "Tesla Coil Help" Assuming your system is wired correctly, you seem to be having a problem with your NST. It's possible that you may either have an electronic NST or an NST that has a built-in Ground Fault Interruptor (GFI). If the transformer has a "reset" button, then it is a GFI type and may not work properly in a Tesla Coil system without some further work. An electronic NST will not work in a regular spark-gap type Tesla Coil. If you disconnect the NST from the system, can you [CAREFULLY!] get an arc from each HV terminal to the case of the NST, do the arcs appear to have the the same size and appearance, and do the arcs "buzz" (at 120 Hz) when you stretch out the arc? If they hiss instead of buzzing, or initially jump the gap and then stop until you unplug and re-power up the NST, or if the NST is physically small and light weight, then you may have an electronic NST. An electronic NST will weight perhaps 2-3 pounds while a regular 15/30 NST will weight 15-20 pounds. If you have a make and model number, or a picture of the NST I may be able to determine if you have the right type. If you'd like to discuss, give me a call at 630-964-2699. Best wishes, Bert
|