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Well, originally I wanted to make a Jacob's ladder which if you haven't already heard can be extremely dangerous! They are high voltage and if you complete the circuit with your finger it can be fatal...So, be very careful or just don't do it.
Most of the instructions I found used a transformer from a neon sign to generate high voltage and make the thing arc. I didn't want to go out and buy a transformer but I did have an old CRT (Cathode Ray Tube) monitor collecting dust. So, I decided to put it to good use and make a variation of a Jacob's Ladder.
Wire (12 Gauge?)
Materials for Insulation
Step 1: SPLICE
Open any monitor up, and one of the first things you will see is a big suction cup attached to the CRT. Attached to it is a wire that is at a few thousand volts higher than ground because there is a capacitor somewhere that is still charged up.
The first thing you should do is put on some oven gloves, and get a piece of insulated wire. Attach one end of the wire to a ground pin (look around on the circuit boards etc.) and poke the other end of the wire under the suction cup until you hear a spark noise. Do it a few times until you are SUPER sure everything is discharged, and even then use a multimeter to check the voltages of everything your hands come near.
A flyback transformer in the monitor generates a few kV that is used to accelerate electrons in the CRT to hit the screen. There should be at least two large leads coming out of the transformer. One goes towards the suction cup near the front of the screen (thats the super high voltage one), another goes to the rear end of the tube (should be more or less 0v).
Cut the high voltage wire that goes to the suction cup, splice in a wire of your own and solder.
Step 2: INSULATE and GROUND
Be sure to insulate the connection with excellent insulation materials such as paper towels and duct tape. (Just kidding, don't do what I did. Use some non-flammable materials to insulate.) This wire will go to one side of the Jacob's ladder.
Follow the other wire coming out of the flyback transformer, and see where it goes. If there is only one red wire coming out of the transformer like was the case with my monitor you will have to find a another place to solder the ground wire. I soldered my ground wire right where the power cable came into the PCB (Printed Circuit Board).
The ground was obvious in my case but you may have to do a little searching to get it right. If you don't ground the circuit right, the electricity will find its own ground, possibly somewhere else on the PCB and cook the whole monitor so good luck! Use a multimeter...
Step 3: FAILED LADDER
Like I said before, I originally attempted to build a ladder for the electricity to climb. I couldn't get it to work after a lot of time fiddling with it. I don't know if there just isn't enough voltage produced by a CRT to have it work effectively?
I built the ladder using wood dowels and copper tubing. The spacing of the tubing, the height off of the board, the spread at the top were all touchy and too critical. I could only get the arc to go up about 4 inches and most of the time the arc stayed where the tubing was closest. I was not impressed. After doing a little research online, I found out that:
A Jacob's Ladder works on the principle that the ionized air in the arc is a lower resistance than the air around it and heated air rises. The arc strikes at the point of lowest breakdown voltage - the small gap at the bottom. The heated plasma rises and even when it is an inch or more in width is an easier path for the current to follow. Eventually, the gap becomes too wide, the arc extinguishes and is reestablished at the bottom.
The gap between the electrodes at the bottom of a Jacob's ladder can be critical. Too wide and the arc won't strike, and too narrow and it won't make it all the way to the top. The lower voltage makes the gap even more critical. I found a slight enhancement that is supposed to work. It's simply a third electrode placed between the strike gap at the bottom of the vee. It is connected to either one of the main electrodes via two 1M ohm high voltage resistors.
When an arc should occur, the following happens...The voltage on the middle electrode floats to the potential of the electrode it's connected to via the resistors. It's easy for an arc to jump the short distance from the other electrode to the middle one. When an arc has struck and current is flowing, the voltage on the middle electrode flies up due to the high resistance value. The combination of high voltage at the middle electrode and the ionized path makes the arc strike all the way across.
That all sounded too complicated for the time I wanted to spend so I chose plan B...
Step 4: FORKS
So, I chose the next best thing Jacob's Forks! I found a couple of old forks and attached the ground wire to one fork and the high voltage wire to another fork. I clamped them down and plugged it in. The arc jumped back and forth inbetween the prongs of the fork. It was a far more spectacular light show than the failed ladder.
I then created four circular cut-outs with my whole saw attached to my drill to create insulating plugs. I cut a path through one side of each of the plugs so that I could insert the fork.
Remember not to touch it while its plugged in - or until you have depleted the capacitor by connecting the two contacts until you hear a pop...
Step 5: FOAM and TUBE
Next, I attached a 3x3x5 inch block of foam to the top of the back of the CRT casing. I cut out a place for the clear tube that will hold the forks. This is to create a place holder and insulate the monitor from the wires. I then placed a clear plastic tube in the space cut out from the foam. The tube will add some protection from the temptation of wanting to grab both ends of the leads and shock myself to death!
Step 6: FORK TEST and FINISH
I connected the lead wires inbetween the plugs to insulate and cut holes in the red caps for the wires. I tested the forks first to make sure it all works before I sealed it off. Looks cool huh?
I sealed off the red caps on the end of the tubes with zip ties and voila! Its done!
(Is anyone enjoying this red carpet?)
Step 7: LIGHT SHOW
The electricity arcs back and forth between the tongs of the forks. You could use any number of metal objects to achieve different effects. Just remember to be careful.
SHOE0007 made it!