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Hallo, I'm new in this forum. Excuse me if my English isn't so good.
test_tube_tony wrote ...
i started playing with the tesla coil cad program and i noticed it has a quarter wavelength resonant frequency number that it spits out. i hadnt heard this term before in my reading so i did some searching on the googles. seems it has to do with wireless power transmission if two identical coils are built but i cant seem to find a very good explanation of the hows and whys. wireless energy transmission seems like it would be something fun to play with tho so if i can incorporate it into the design it would be a bonus lol.
Some people think that the length of the wire of the secondary coil should be one quarter of the wavelength of light in the free space at the resonance frequency. Maybe even Tesla himself thought so. I think there is no advantage of disadvantage if this condition if fulfilled. This condition is based on the assumption that a current and voltage wave is travelling along the wire with speed of light. But this is not correct. There are other theories about wave propagation in the secondary which are more suitable, e.g. this: http://www.mwr.medianis.net/pdf/Vol7No2-07-JCorum.pdf Maybe you find some more information about the "quarter wave" theory with the google search "tesla lambda/4".
thanks monokel. :) just an update, i managed to snag a 12kv 30ma transco nst with no gfi off ebay. $54 so not bad. going to keep gathering parts over the next several weeks/months. :)
quick question. started hooking all my capacitors together. id like to add a bleed resistor/s for safety. should i use one large resister for the whole capacitor bank or should i use several resistors to drain individual caps? ive seen it done both ways and i was wondering which way is best/most cost effective? would 1 megohm .5 watt resistors do the trick? heres the schematic to what im thinking... the final tank cap would have 22 .15uf 2kv caps strung together in this manner.
Registered Member #2628
Joined: Fri Jan 15 2010, 12:23AM
Location:
Posts: 627
thats an interesting way, but most of the time, ive seen it done with a resistor put from terminal to terminal of the capacitor, and then you wire up the capacitors as normal.
also, Id think an individual resistor for each capacitor will be a good idea, so incase for some reason your master resistor gets disconected compared to a bunch of resistors for each capacitor.
my last question about the mmc is how likely are the capacitors to flash over between each other? i wanted to try to save space by putting them together side by side in a 4 layer battery pack like brick but from what im reading this may not be wise. ive already put several together like this but its not a problem to unfold them out flat and space em out on some sort of plastic panel. these are the caps im using.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068
quicksilver wrote ...
QUICK QUESTION ABOUT SECONDARIES & FUNCTIONALITY
My nephew is building a coil and his first attempt at a secondary is not too pretty. There are no kinks, but there ARE overlaps; quite a few. I hate to tell him he has to wind that thing over again if it's possible that it will function, but the amounts of overlaps are great. I know that kinks can create corona points, what problems is he facing with overlaps? He saw mine and wanted to try to build one. He's a really fast learner & generally quite responsible with dangerous items but I am very far from knowledgeable on TC building idiosyncrasies.
I don't have a camera handy but basically it's 3" coil with tight 28awg coated wire with overlaps just about every inch; occasionally multiple overlaps. They are tight and the first layer of clear-coat lacquer made the unit quite solid - no slips of wire, it's firm.
Is it really a much better idea to have him re-wind a new coil form than attempt to push on with this? I was thinking that if the thing were coated heavily it may be OK. But I'm not sure, as I have not made one like this. He's 16 and just getting the concept:this is his first one. If I need to tell him to wind it over, what is the reason why overlaps are ruinous?
Thank you
Just go with the existing secondary. A few overlaps aren't going to hurt you. And even if it did, you'd still be winding a new secondary anyways.
You have nothing to lose by going with the existing secondary. Try it out. If it has problems, then wind a new one.
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
That's what he did: being 16, he simply wanted to see the thing make some sparks and I could not offer a plausible explanation why it should not work. It worked. The streamers were fair; no appreciable racing sparks as it seems appropriate in other respects.
I explained the value of putting something together with care & quality, but I also know he's 16 and will do a quality one when he himself is dissatisfied with "quick & sloppy" workmanship.
I was surprised that it worked however. I had nothing to say as to why it should NOT function. This is a secondary with appreciable overlaps: no kinks however. And it was coated quite thickly. It was an interesting experiment in coil requirements.
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Secondary advice for first coil
