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Registered Member #9130
Joined: Sat Dec 29 2012, 03:31PM
Location:
Posts: 17
Hi everyone- Im just wondering where I can find good info on a couple things, or perhaps some of you know and can explain! Sorry
How exactly is energy transferred between primary and secondary in a Tesla coil? From my research TCs have pretty loose coupling of magnetic fields between primary and secondary. Given this, how exactly does all that energy transfer occur at a decent efficiency? Does the key lie in that both circuits are tuned to the same resonance frequency?
Also, is there any "sweet spot" for coil placement- if you look at my photo the prim and sec are not that close- about 5 or so inches away. This is going to be a static spark gap TC with future upgrades once I can afford better materials than those found in my dads shop!
Last question- my secondary has a few turns that have "jumped" - I've handled and transported it a lot and its getting a little worn. Is there risk that my secondary will try to arc to itself? My gut says yes, but I don't want to re-wind that thing ;)
Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
Hi
You say:
Energyandfrequency wrote ...
How exactly is energy transferred between primary and secondary in a Tesla coil? From my research TCs have pretty loose coupling of magnetic fields between primary and secondary. Given this, how exactly does all that energy transfer occur at a decent efficiency? Does the key lie in that both circuits are tuned to the same resonance frequency?
Yes, the key lies in tuning. However, the coupling has nothing to do with efficiency. It just says how much of the magnetic field of the primary is used by the secondary winding, the remaining field does nothing at all (maybe heats up surrounding objects) - so no energy is lost, just stored.
Energyandfrequency wrote ...
Also, is there any "sweet spot" for coil placement
Yes. Usually the best coupling is the highest one which still doesn't give spark-overs, but this is not a rule, sometimes you need a high-Q in the primary tank circuit so you deliberately decrease the coupling. I think it has also something to do with quenching the gap in an SGTC - but I have no experience with this (and if I was to build an SGTC, I would go for a rotary gap anyway)
Energyandfrequency wrote ...
Last question- my secondary has a few turns that have "jumped" - I've handled and transported it a lot and its getting a little worn. Is there risk that my secondary will try to arc to itself? My gut says yes, but I don't want to re-wind that thing ;)
For pulsed coils especially SGTCs, this might be a problem and could cause interturn arcing. Always coat the secondary with some kind of varnish after winding, to fix the turns in place.
Along with Richie Burnett's website, I would also recommend checking out this site as well. It is a big help when it comes to designing your coil. http://www.teslacoildesign.com
Also, 5 in. between the secondary and the primary does seem a little bit far apart - and try not to handle the secondary too much, because the salts and oils on your hands might get on the coil and induce racing arcs (which is why it is a good idea to coat the secondary with varnish as Dr. Dark Current suggested). Otherwise, your coil looks good and I look forward to seeing pictures of it in action!
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Couple TC theory questions and photo
