Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx> Hi JT,Hate to disillusion you, but the same thing happens at 120Vac. Static spark gap operation is chaotic in nature. The best way to see what happens is to do a computer simulation and look at the waveforms. Even if you assume an ideal spark gap that fires at precisely the set voltage every time, you can still have half cycles where multiple firings occur and other half cycles where no firings occur. You just cant think of a static gap only firing at the peak of the 60Hz waveform consistantly. The reason for this is the transcients the spark gap firing introduces to the steady state response and can be difficult to explain as well as to understand. The voltage on the spark gap is the sum of the steady state and transcient responses. Everytime the spark gap fires, a new transcient response is started. The BPS (breaks per second or firings per second) will vary above or below the 120 peaks per second of the 60Hz line voltage as one closes or opens the main gap. As you close the main gap below its optimum setting, it is very possible to get 300-400 BPS. If the gap is too wide, it is very possible to get less than 60 BPS. One way to get consistant 120BPS is to use a synchronous rotory spark gap (SRSG).
Dont worry about the chaotic nature of the static spark gap, it is just a fact of life. The larger than resonance (LTR) value of Cp = 1.6*Cres is based on getting around 120BPS with the firing gap set at peak rated voltage of the NST (1.414*Vout_rms).
Gerry R.
Original poster: Mddeming@xxxxxxxIn a message dated 11/26/05 3:11:15 P.M. Eastern Standard Time, tesla@xxxxxxxxxx writes:Original poster: "JT Bowles" <jasotb@xxxxxxxxxxx> So you are saying it will randomly and sparratically fire faster, then slower, then faster....and so on? Not good for my coil. If this is what you meant, im keeping my NST at 120VACAny static gap has some variation in its firing interval. At a fixed voltage, the number of pulses in any say 2-second interval is quite consistent. The total number per second increases with voltage, but the length of the conduction period, and the interval between them may vary considerably from cycle to cycle. These spark gap jitters can be seen with a spectrum analyzer and /or waveform analyzer. This is quite normal. A rotary gap has much less variation than static gaps and solid state switching circuits have even less. Eveb at 1`20V, there are some irregularities, it's the nature of the beast.Matt D.