vax1:swifty (04/14/83)
All of us have seen the "Jacobs Ladder," that marvelous toy that has the climbing arc. I would like to build one, but I have been unable to find cookbook instructions on its construction. Obviously, I could start designing one, but I'd rather read something about the device first. Are there any major constraints? I think one is that the arc must be fairly high current to heat the air (which causes the arc to rise). I will appreciate any help in locating a reference. Post to net.physics if you think it is of general interest, otherwise respond to me via mail. Steve Swift ..decvax!microsof!fluke!swifty
mjs (04/15/83)
To build a Jacobs Ladder you will need: 1. A NEON sign transformer with 115 vac in and 12Kv to 15Kv at around 3 ma. 2. A block of wood(very dry) or heavy plastic and two metal screws about No. 10 size, set into the wood about 6 cm apart. 3. Two copper rods that are able to be bent into a V shape that is about 2 cm at the bottom and about 7 cm at the top. They are to connected to the two screws and from the Ne sign xformer to the screws with T.V. high voltage wire(Anode wire) good to 25Kv. The screws hold the rods in place. 4. Plug it in and burn. Watch that you don't end up fried or have the FCC arrest you for RFI transmitting. Mark Schiff WECO c/o BTL Whippany N.J.
vax1:swifty (04/15/83)
As a follow-up: which is the best choice, AC or DC? I would guess DC because it would not try to extinguish itself by going to zero volts as AC does. Any thoughts. Steve Swift ..microsof!fluke!swifty
dmmartindale (04/17/83)
Instead of a neon sign transformer, you might try the ignition transformer that is used on oil-burning home furnaces. They seem to be rated at 10KV and 10mA. Note: 10mA at 10KV is 100 WATTS, so stay away from the thing when it's turned on. It could give you an awfully nasty shock.
knutsen@SRI-UNIX (04/18/83)
From: Andrew Knutsen <knutsen at SRI-UNIX> A good source of copper rods is a welding supply store. If youre going to use it in uncontrolled environments, you might want to put a clear plastic tube around the thing... you might be liable if somebody zaps themself. Has anybody had experience making Tesla coils with neon light xfmrs? Ive always wanted to do that... what a party gag (with the amperage suitably low, of course).
bormanp (04/22/83)
Using AC for a jacobs ladder works just fine. I have had one for several years, all it is is a 12,000 volt luminous transformer and a couple of wires. No problem with it it "going to zero volts", after all, ac only passes through 0 volts and does not go to 0 volts. The arc goes up to 3 or 4 inches (only 2 on a breezy day). -Paul R Borman -St. Olaf College ihnp4!stolaf!bormanp