rats@ihuxz.UUCP (07/04/90)
Are spark coils still manufactured? I don't mean the little Model-T 1/2" jobs, I mean the big ones which give sparks 2" or greater. How much do they run? Where could you purchase antique spark coils from and for how much? Just curious.
larry@kitty.UUCP (Larry Lippman) (07/04/90)
In article <9007032018.AA27882@ucbvax.Berkeley.EDU>, rats@ihuxz.UUCP writes: > Are spark coils still manufactured? I don't mean the little Model-T > 1/2" jobs, I mean the big ones which give sparks 2" or greater. Induction coils of the type you describe have not been used in probably 50 years for any purpose other than teaching on a secondary or vocational school level. Their use for even teaching has most likely diminished to very little in say, the past 25 years as the general nature of a science or physics curriculum has changed. In years past, the major vendors of such induction coils were the Central Scientific Co (Cenco) and the William Welch Co. As far as I know, Cenco has been out of business for 20 or so years, and Welch survives only in its vacuum pumps as the Sargent-Welch Co. Both Cenco and Welch catered heavily to the educational marketplace. The only surviving vendor of educational scientific apparatus from the "old days" is Fisher Scientific. I looked in a Fisher Educational Materials catalog from the early 1980's (separate and distinct from the regular Fisher catalog), and found an induction coil of the type that you mention. It's price was $ 210.00. Since we only order from the regular Fisher catalog, I don't have a more current educational catalog from which to quote a price. > Where could you purchase antique spark coils from and for how much? There are a few dealers who specialize in antique scientific apparatus. One who comes to mind is Crystal Payton of Sedalia, Missouri. I don't know what the going price is for such an induction coil, but it is probably not cheap. Personally, I have a Cenco coil which easily makes 4 inch sparks. It is all polished wood, and dates to around 1940. I have not powered it up in several years, though, for fear of damaging the coils, the insulation on which is now obviously rather old. Larry Lippman @ Recognition Research Corp. "Have you hugged your cat today?" {boulder||decvax||rutgers||watmath}!acsu.buffalo.edu!kitty!larry VOICE: 716/688-1231 || FAX: 716/741-9635 {utzoo||uunet}!/ \aerion!larry
dspeed@sactoh0.UUCP (Dave Speed) (07/06/90)
In article <3829@kitty.UUCP>, larry@kitty.UUCP (Larry Lippman) writes: > In article <9007032018.AA27882@ucbvax.Berkeley.EDU>, rats@ihuxz.UUCP writes: > > Are spark coils still manufactured? I don't mean the little Model-T > > 1/2" jobs, I mean the big ones which give sparks 2" or greater. > > Induction coils of the type you describe have not been used in > probably 50 years for any purpose other than teaching on a secondary or Coils of this type are still available from suppliers of antique gas engine restoration parts. They tend to be more on the small side than the large, but you might inquire further. Try the advertisers in Gas Engine Magazine, PO Box 328, Lancaster, PA 17603 (717) 392-0733. John Wanat at (203) 938-3771 advertises custom made low tension coils for ignitor fired engines; he may be able to help. Enjoy ! Dave -- Dave Speed - d.b.a warp speed; data purveyors since 1989 (known universe) !ames!pacbell!sactoh0!dspeed or dspeed @well.uucp 8908 Van Gogh Circle, Fair Oaks, CA 95628 BELL: (916) 863-7226
eric@electro.com (Eric) (07/06/90)
Oil furnace transformers can apparently give 50kv sparks and up while car ignition types give 35kv. To get some real sparks you need a Tesla coil. To do this you need to make your own transformer on a carboard form with some hi-V insulation and an oscillator driving a high V high I primary winding with a very fast slope on the rising and falling edges. Apparently it can be done with tubes. I do believe that transistors would go up in smoke with the back emf so perhaps a moderate voltage (100v pk) feeding a spark thru a neon or other type of flash tube? I have tried a tube oscillator back many years ago but I believe that high voltage leakage in my tansformer prevented it from working. Note: oil burner transformers are very dangerous. I have had pulled muscles, burns and bruses from being thrown. One side of the secondary is always grounded so you can not stack them for higher voltage but perhaps it could be done with car ignition coils? It would probably be easier to get a high perf ignition coil and driver to get 50+ kv. Eric
grege@gold.GVG.TEK.COM (Greg Ebert) (07/07/90)
Side note : The more current you can muster-up, the more dazzling the arcs. I once eyewitnessed a 66KV transmission line arcing 8 feet. Must have been hundreds of amps. The Tesla coil at the Griffith Park Observatory in LA is a definite must-see. I've been scratching my head off-and-on for a few years about how to construct a HV setup running in the 1-2KW range, but the problem which always comes back is how to insulate AND maintain acceptable core-losses in the transformer. A good place to start might be a 16Kv-240v stepdown transformer like the power companies use in rural areas, but I have no idea of where to get one. Safety is another issue. One zap, you're DEAD. Another concern is the RF energy emitted, which could have dire consequences concerning aircraft navigation.
collie@ubvmsd.cc.buffalo.edu (collie) (07/07/90)
In article <2082@electro.com>, eric@electro.com (Eric) writes... >Oil furnace transformers can apparently give 50kv sparks and up >while car ignition types give 35kv. To get some real sparks you >need a Tesla coil. To do this you need to make your own transformer >on a carboard form with some hi-V insulation and an oscillator >driving a high V high I primary winding with a very fast slope on >the rising and falling edges. ^^^^^^^^^^ ^^^^^^^^^^^^^ Eric,is this a saw tooth oscillator ? I'm deeply intrested in HV power supply,and I have heard about those oil burner transformers from a friend.He said once a peepingtom used to bother his sister-in-law so she told one of her other sister's husband about the problem,as she was really afraid to go back to her house alone. The crazy (EE) nut took one of those transformer and wired it to the tom's favorite window,he took the secondary and attached it to a stake in the ground under the window,soaking under the window well with water with the other side attached to the screen.Then he sat in the dark with a big switch to send power to the primary (on command),while his sister-in-law is in the house. The tom appeared on'que'at the window,and again trying too remove the screen,all of a sudden the brother-in-law throw the switch.The arc jumped across about sixteen inches,and hit the tom throwing him about ten feet from the window.Then he thought the tom was dead,since he layed there for a few good seconds without moving,but the good lord was with him.So he got and staggered away never to return. People do some crazy things without thinking sometimes,he was lucky the tom didn't die other wise big problems,but I guess he felt something had to be done as the cops did nothing. ****************************************************************************** collie ***************************************************************************** x
jimc@isc-br.ISC-BR.COM (Jim Cathey) (07/10/90)
In article <2082@electro.com> eric@electro.UUCP (Eric) writes: >Oil furnace transformers can apparently give 50kv sparks and up >while car ignition types give 35kv. To get some real sparks you >... > Note: oil burner transformers are very dangerous. I have had > pulled muscles, burns and bruses from being thrown. They are nasty, at that. I made a Jacob's ladder out of one once (in my misspent youth) that wasn't too impressive as a ladder, but it would start on fire a piece of paper placed in the arc! 'Real' ladders have much less current and will merely perforate paper placed in the arc. Sometime later, we had some problems with a steer that would just walk through the electric fence (he twitched a little, but it didn't stop him) and get into the barn to pull down the haystack at night. Pissed at having to fix the fence every day and clean up after this critter I 'enhanced' the electric fence. (The fence in question was a short temporary section we had put up for the summer.) I disconnected the temporary fence from the rest of the fences, and got out an old electric fencer. This fencer used a rocking mercury switch to intermittently supply line current to a HV transformer. I tapped off the primary of this transformer and ran this power to the primary of my oil transformer. The secondary went to the fence. Powered up the fence -- nothing. Looking into matters I found that the new fencer burned through all the plastic fence insulators and shorted out to the metal fence posts. Grumbling that it mightn't be easier just to _shoot_ the damned steer I replaced all the insulators with porcelain ones. Success! I went into the barn to watch. After I was out of sight for a few minutes the steer came up to go under the fence as was his usual habit. He got halfway under when the charge hit him (the mercury rocker was slow). GRAWWWWWWWW, he fell to his knees, scrambled backwards and ran extremely fast to the other end of the field. He didn't come close to the barn for days! End of problem. I left the killer fencer up for a few days just in case, then restored things to normal. One nice artistic effect was the pretty purple glow around all the insulators at night! Nasty stuff, that HV. In retrospect, I'm lucky I didn't kill the steer, though I doubt I would have been heartbroken about that by that time -- _Dad_, on the other hand... +----------------+ ! II CCCCCC ! Jim Cathey ! II SSSSCC ! ISC-Bunker Ramo ! II CC ! TAF-C8; Spokane, WA 99220 ! IISSSS CC ! UUCP: uunet!isc-br!jimc (jimc@isc-br.iscs.com) ! II CCCCCC ! (509) 927-5757 +----------------+ "With excitement like this, who is needing enemas?"
umapu02@sund.cc.ic.ac.uk (D.A.G. Gillies Supvsr Dr K.J. Bignell) (07/14/90)
In article <2885@isc-br.ISC-BR.COM> jimc@isc-br.ISC-BR.COM (Jim Cathey) writes: >In article <2082@electro.com> eric@electro.UUCP (Eric) writes: >>Oil furnace transformers can apparently give 50kv sparks and up >>while car ignition types give 35kv. To get some real sparks you >>... >> Note: oil burner transformers are very dangerous. I have had >> pulled muscles, burns and bruses from being thrown. > >They are nasty, at that. I made a Jacob's ladder out of one once (in my >misspent youth) that wasn't too impressive as a ladder, but it would start >on fire a piece of paper placed in the arc! 'Real' ladders have much less >current and will merely perforate paper placed in the arc. > >Sometime later, we had some problems with a steer that would just walk >through the electric fence (he twitched a little, but it didn't stop >him) and get into the barn to pull down the haystack at night. Pissed >at having to fix the fence every day and clean up after this critter I >'enhanced' the electric fence. (The fence in question was a short >temporary section we had put up for the summer.) [ etc.. stuff deleted..] I made a fairly puny version out of the induction coil from a car.I used a battery buzzer to trip the current and this would generate a spark about 2 cm long ie approx 50 kV in dry air with 18 V in the primary.But you guys take the cake.Where,oh where (please tell me) can I obtain one of these very interesting devices.I have a healthy fear of death by electrocution and have no particular homicidal tendencies (honest).Besides,I have a DeLorean and need 1.4 jigger-watts (sic) spare. __________________________________________________________ ---------------------all replies to :- ------------------ ------The Magic Christmas Cracker Motto Factory Ltd.------ -------c/o umapu02@cc.ic.ac.uk (David A.G. Gillies).------ -If you didn't get caught,how can you be sure you did it?- ==========================================================