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Jacob's LadderHot air rises. Electric arcs are plasma. Plasma is very hot. When two near-parallel wires are charged to high potential, an electrical breakdown occurs at their closest point, and in a 'V' this is the bottom. The newly formed low voltage arc being very hot starts to rise up the V electrodes until the distance between the electrodes is so great that the arc becomes unstable and extinguishes. The voltage rises again and the process repeats. To make a reliable jacob's ladder you'll need at least 10kV, but 15kV is better. The reason that such a high voltage is needed is due to the fact that electricity jumps 1cm per 10kV. Sure you could use a 4kV transformer and put the electrodes 4mm apart at the bottom, but if you do that the arc will be so small that it doesn't rise. Instead it'll just sit at the bottom of the ladder and stay put. A neon sign transformer is an ideal transformer for a jacob's ladder. Voltage is what ignites the arc, but current is what keeps it going. To make an impressive jacon's ladder I'd use at least 30mA, or more if you have the ability to. A 15kV 30mA NST is great for a jacob's ladder, even if it is a little heavy. Jacob's ladder electrodes need to be self supporting, so that mans they need to be at least semi rigid. The perfect material for making the electrodes is 1/4" aluminum wire, sold at craft stores in the sculpting isle. If you can't find that aluminum wire, metal clothes hangar wire does a fine job, even if it doesn't look as pretty. Here is a video of a roughly four foot tall jacob's ladder powered by a 15kV 30mA NST. |