A correction to my statement: I said "It conducts and also forces a breakdown at the safety gap (bang)."This is not correct. The main gap won't conduct. The voltage on the cap simply over-charges to the breakdown voltage of the safety gap and then "bang", the safety gap dumps the cap energy.
Cheers, Bart bartb wrote:
I wanted to explain my theory a little better:If the primary is hit (racing spark gets near the bottom and arcs to the primary or rail gets hit and arcs to the primary), the voltage at the main gap opposite the charging stationary electrode voltage is higher (the felt potential across the gap is lower) and thus the difference across the gap does not reach breakdown (causing mis-firing with rotary [time dependent for this to occur] or no firing if a static gap). The cap however continues to charge. Once the potential across the gap is high enough to breakdown, there is a very high voltage on the cap. It conducts and also forces a breakdown at the safety gap (bang). So add primary strikes as another cause to this phenomenon.Take care, Bart bartb wrote:In cases where I've experienced bangs, it appeared the safety gap was producing the bang. In many cases, this was associated with anomalies such as rail to primary flash-overs and racing sparks running down to the ground at the bottom of the secondary (both of which are tied to the safety gap and both can also be tied to the main gap via the primary). In this particular case, I couldn't tell if it was a racing spark or a primary flash as it was on the back side. But considering the brightness and reflection, it may have been a racing spark as it did illuminate the entire back side of the coil. I have sometimes wondered if these high voltage breakdowns to ground had altered the gaps ability to fire (causing a mis-firing or two) allowing the cap to charge higher and as a result a following safety gap breakdown (thus the flash and bang). From the video however, I could not make out the bang well enough or play with the video enough to note a difference in time between flash and bang. This theory would support higher occurrences of safety gap breakdown with higher coupling and with mis-tuned coils.Regards, Bart Lau, Gary wrote:In my experience, loud bangs are the safety gaps firing, due to the presence of a too-high cap voltage, so the safety gap discharges the bang instead of the main gap. If the safety gap is firing just because of a primary strike, I wouldn't think that it would be nearly so loud, as the current is many times smaller than if the gap is discharging the primary cap into the tank circuit. Could it be that there was a too-high cap voltage, the safety fired for that reason, and the larger than normal bang caused a longer than normal secondary spark to strike the strike rail?Regards, Gary Lau MA, USA-----Original Message----- From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of David Nelson Sent: Thursday, October 02, 2008 10:24 AM To: Tesla Coil Mailing List Subject: Re: [TCML] Strike rail hits and loud bangs Is there a chance that the loud bang is a spark between bottom of thesecondary and the inner turn of the primary? Overcoupling. I had this and I removed half a turn from the inside of the primary and re-routed the wiring (down and out) to fix the problem. I kind of feel that performance went downslightly, but no more loud, annoying and scary bangs. Dave Nelson ----- Original Message ----- From: "Stephen J. Hobley" <shobley@xxxxxxxxxx> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx> Sent: Wednesday, October 01, 2008 11:37 AM Subject: [TCML] Strike rail hits and loud bangsWe have a fairly simple coil using a 60ma NST. Recently I changed the tappoint on the primary and by chance hit a really sweet spot.Usually the Tesla Tuner is pretty accurate and gives good results, but inthis case it did not indicate that this tap point was a good one.The streamer length has increased by at least 50% - but we did notice some rather worrying "bangs" from the Terry filter spark gap when the strike railis being hit. Is this normal? Is it possible to tune a Tesla coil into a self-destructive state? I would take some pictures, but the darned thing scares me to death... :-) Steve_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla_______________________________________________ Tesla mailing list Tesla@xxxxxxxxxxxxxx http://www.pupman.com/mailman/listinfo/tesla
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