Instructables

How to make a Jacob's Ladder!

A Jacob's Ladder (otherwise known as a high voltage climbing arc) is an eye-catching prop for Halloween and is a necessity for all aspiring mad scientists. Jacob's ladders work by ionizing the air and drawing an electrical arc at the bottom of the ladder. Soon, the ionized air gets much too hot to stay in the same spot so it rises -- bringing the arc with it and creating that shocking effect.

So let's get started!

 
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Step 1: Materials

The main thing you need for this instructable is a high voltage power source. Most people (including me!) use neon sign transformers to do this. Other examples of high voltage power supplies might be: a furnace ignition transformer, or a flyback transformer from an old TV. You can pretty much use anything you can get your hands on as long as it generates more than five thousand volts (5 kV). Remember that the more volts it puts out, the father you can have the electrodes from each other. If you do use a neon sign transformer, stay away from the solid-state versions.

You will also need a pair of electrodes. Thin copper tubing works superbly for this, as it is very conductive and easy to bend. I went cheap and used a coat hanger that was laying around. Be aware that most coat hangers have some type of paint or plastic coating that will have to be removed. I had to sand mine quite a bit before the coating was gone.

A non-conductive base must be used to mount the electrodes. A non flammable base is also a good thing to have if you are worried about setting something on fire. Note that at excessive voltages, wood no longer stays an insulator, and starts to conduct electricity. If this does happen, you can count on that wood to ignite.

Some high-voltage wire is also recommended. I couldn't find any, so I used some 12 gauge hook-up wire. The thicker the gauge and the insulation the better!
sguy13 years ago
hello i am have trouble finding the required transformer that you have said because i am from place where such transformer is not available. please can you suggest me alternative transformer. i have one transformer that i took from the old tv but it says that 110v,220v in one side and 17.5v in other one. is it appropiate transformer? i hear that tv has an output of more than 10kv. if so is it 17kv instead of 17.5 v?
duct tape (author)  sguy13 years ago
What type of tv is it? Can you take a picture of the transformer/tv?
You can also use an oil burning ignition transformers to do the job. Where do you live? You can usually find these sorts of things online, that is where mine came from.
sguy1 duct tape3 years ago
tv is 20 years old.unfortunately i haven't got any cameras. i live in Nepal , Kathmandu. i think the transformer works on 110 volt and 220 volt as well it has got 4 wires in input and two wires on output with 17.5 volt.
duct tape (author)  sguy13 years ago
Sorry, 17.5 volts just won't cut it. You need at least a couple thousand volts to make this work. If you can find an old microwave oven, you can take the transformer out of that, which IIRC puts out several kV.
sguy1 duct tape3 years ago
i have now made Jacob's ladder from black and white tv circuit(the whole circuit) but the spark won't climb up. can you give me any suggestion for that problem!!
duct tape (author)  sguy13 years ago
Does it initially create a spark at the bottom?
sguy1 duct tape3 years ago
i have used crocodile clips at the bottom. and the sparks is produced from the middle of the rod but not all the way to top. it only climbs few inches.
duct tape (author)  sguy13 years ago
try decreasing the angle that they spread apart. Like instead of >< make it \/
carpespasm4 years ago
I found a Franceformer transformer at a local junk shop the other day and used your and a couple other 'ible's ideas to make this:

This is amazing. It's similar to the 5 minutes high voltage power supply 'ible.

Could I start off with that ible? I'm having trouble identifying the pins on my flyback transformer.
mtdna4 years ago
What are the safety issues?
I can say from personal experience the concerns are electrocution if you get hit with it long enough. Severe pain if you get bit by it anyway. Doubly so if you don't ground the transformer right.

I got bit by mine when the transformer and HV line got close enough for one to induct to the other and I tried to hit the breaker without realizing the case was live. Jumped about 6CM to my fingertip and hurt worse than any shock I've ever had. Didn't leave a RF burn for some reason though.
duct tape (author)  mtdna4 years ago
It produces ozone and to a much lesser extent NO2 (poisonous). If in long-term use, you might want to consider wearing sunglasses or putting tinted glass around it to protect from UV.
Hi V wire can be spark plug wires for a car. free ones from a local repair shop, or just buy some from an auto junk shop. Ought to be real cheap like that! Old tvs are also a good source for the wires.... big screen projector units are often tossed in favor of the new lcds etc, and have multiple hi v wires inside.
jeff-o4 years ago
Sweet, I scored one of those transformers from my high school way back when.  Much fun was had by me.  ;)
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