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Registered Member #1127
Joined: Mon Nov 19 2007, 12:08AM
Location:
Posts: 139
Good point Herr, But I think tuning is a really key issue here. How can you assume that no ground has been applied? I've seen plenty of coils flash over due to poor tuning.
Registered Member #1617
Joined: Fri Aug 01 2008, 07:31AM
Location: Adelaide, South Australia
Posts: 139
Herr Zap,
i can understand why you may call my advice 'bad', but I think you will agree that the only danger it produces is a shock hazard from the streamers, which as many should already know is ALREADY there. You should not be touching the streamers in any case, as a secondary to primary arc can provide the 'leathal' connection anyway. My advice was based on the fact that 1) its a small low powered coil and a suitable ground is not always available to everyone and 2) It dosent 'introduce' a possibly fatal hazard, this hazard is already there.
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
MOT man -
You wrote: "How can you assume that no ground has been applied? I've seen plenty of coils flash over due to poor tuning."
After I posted that Max's primary - secondary arcing was most likely due a problem with secondary grounding, Max confirmed that his secondary was not grounded.
(12-31-08, 3:58 PM) "The secondary - is not grounded."
This type of primary-to-secondary arcing is NOT what is typically seen as an artifact of "poor tuning". This is EXACTLY what is seen when the secondary is not grounded.
So, not an assumption, as I have seen this exact symptom previously with my own coils, and the coils of others, when the secondary ground was not connected.
Registered Member #160
Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938
Yeah, it's pretty obviously not grounded. You don't get that with a grounded coil no matter how out of tune it is. The reason he is getting no output when the secondary is grounded is a tuning problem.
Registered Member #1127
Joined: Mon Nov 19 2007, 12:08AM
Location:
Posts: 139
Herr Zapp wrote ...
MOT man -
You wrote: "How can you assume that no ground has been applied? I've seen plenty of coils flash over due to poor tuning."
After I posted that Max's primary - secondary arcing was most likely due a problem with secondary grounding, Max confirmed that his secondary was not grounded.
(12-31-08, 3:58 PM) "The secondary - is not grounded."
This type of primary-to-secondary arcing is NOT what is typically seen as an artifact of "poor tuning". This is EXACTLY what is seen when the secondary is not grounded.
So, not an assumption, as I have seen this exact symptom previously with my own coils, and the coils of others, when the secondary ground was not connected.
Regards, Herr Zapp
Haha... Herr Zapp to the rescue once again! What we do without you! I have seen this too Herr. It is obvious as you stated... duh. - anyways you seem tense - go have a drink! Its 2009 - run your coils and make some noise.
Registered Member #480
Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644
Frosty -
Connecting the bottom of the secondary to the primary coil DOES introduce a new and very hazardous operating condition that is much more dangerous than just potential contact with a secondary streamer.
When the bottom of the secondary is connected to an earth ground, the secondary system is "isolated" from the primary circuit, and the AC line current. There is magnetic and capacitive coupling between primary and secondary coils, but nothing that is capable of carrying high current. With a small or medium sized coil (300W -1.5 KW input power), getting struck by a secondary streamer under these conditions may yield a very unpleasant shock, but it's not likely to be fatal.
As soon as you electrically connect the secondary to the primary circuit, you have made a very significant change to the maximum current that could be present in a streamer. There is now a direct path, through a streamer, to the AC line. Under worst-case conditions, many amps of AC line current could be superimposed on the milliamperes of normal secondary current. If you happened to be contacting a grounded object (or were even near a grounded object) and were to be struck by a by a streamer, you could be exposed to many amperes of current.
Seeing as Max is "just tinkering" with his first coil, we need to be very careful that the advice we give him is technically sound, and we need to emphasize the need for safety and caution when designing, building, and operating a coil. Most casual TC "tinkerers" have no prior experience with high voltage, and may have no idea of the potential lethality of the voltages and currents present in the primary circuit of even a small Tesla coil. We should emphasize the need to understand the hazards involved, the need for bleeder resistors on HV capacitors, the need to manually discharge and short caps before working on a TC (even if the caps have bleeder resistors), the need to keep one hand in your pocket when working around HV, etc, etc.
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Problem with Secondary to Primary Strikes
