Hey Marko, tell your neighbor "good job"!These coils can have wildly swinging currents. Their not necessarily at 20A for a long duration, but long enough to blow fuses if the fuse isn't designed for the time domain. Use time delay fuses if possible and look at the delay tables for the fuses. Bussman has all that data at their website. I like to go 140% beyond the calculated current (15A without a variac, 17.5 with). So 20A fuse without a variac, 25A with. Time delay is important. If you use a quick blow, it will blow every time.
Depotting is a fantastic thing! Bet you'll never hear anyone else on the TCML say that! It is a lot of work and not for those who would rather just pick up another transformer. But if you depot the tranny, you can then mess with it. It's not easy to get the tar out without destroying windings. You have to have a forceful and yet gentle touch at the same time. Hard to explain if you haven't yet tried it. But you learn a lot about the transformer by messing with it physically. This kind of knowledge must be experienced. It's really up to you. All I can offer is my particular first NST depotting experience. If it seems too much, then simply get another tranny.
http://www.classictesla.com/photos/nstrepair/nstrepair.htmBTW, I use gasoline as a solvent. Many on the list extremely criticize the use of gasoline. I personally grew up using gasoline (father was a burly mechanic). I learned to use gasoline as solvent for heads, pistons, crankshafts, blocks, etc.. It's just what I am experienced with. Some say Kerosene is a better choice. I've not liked the smell or the wait time with Kerosene (very slow as a solvent).
Take care, Bart mark olson wrote:
To: "'Tesla Coil Mailing List'" <tesla@xxxxxxxxxx> Subject: current & fuses Hi gang,I ran the coil for friends and neighbors last night. I actually worked on it more than I ran it,never the less, we got a nice show for five runs of about a minute each. Each run ended with a blown 20A fuse. My transformer is .120mA @ 120V.The more I work on this coil, the less I know, so I am asking on the list.Please correct me where I am wrong. My understanding is that current and voltage are inversely proportional.therefore my xfmr mains current draw should be x where 15000V / 120V = x / .120A so x=15A.The xfmr is dead. case is swollen. Should I bother to de-pot it and attempt a rebuild / shunt removal?Would an ammeter redlined @ 15 A aid in setting SRSG? Am I Waaay off base??BTW, my next door neighbor, a carpenter, solved the cap blowing problem, the cases of these little oil filled snubbers should not be touching. One shorting to case will cause adjacent caps to short to case. A serpentine string solved that.Now I wonder what over amped the xfmer. Of course, after a long day, several beers, and my propensity to "pour the coal to it" is a factor. I am only getting < 40' streamers instead of the supposed 70'"o 80" possible. Is this due to an under-sized toriod?Or only 700 turn secondary instead of 1000+ ? Thanks again, Marko
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