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Jacob's ladder with TV transformer

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zachtheterrible

Active Member
'ello everybody

I recently acquired a broken tv from my friend. In that Tv is a flyback transformer, which means high voltage, which means i would like to make a jacob's ladder :lol:

There are three wires coming out of it:
1. 40kvdc red wire, suction cupped to the crt.
2. 20kvdc white wire
3. 3kvdc white wire

The transformer is connected to the circuit board in 10 places, in a circle. The connections are also numbered . . . if that helps?

Questions:
1. The wires say that they are DC, will DC work with making a jacob's ladder?
2. Which wire should i use? I would like to use the 40kv one :twisted:
3. How do I connect it up? Ground to one side of the ladder and the 40kv (hopefully :twisted: ) to the other side?

SAFETY:
1. Don't touch it or get near it while its on (duh). The spark can jump to you.
2. I hear that this thing makes ozone gas, which is not good to breathe
Any other things I should look out for?

Thanx :lol:
 
pianoman said:
What's a jacob ladder?

A Jacob's ladder is an arrangement of two long wire electrodes in a "V" shape. The electrodes are connected to a source of high voltage, which creates an arc at the bottom (where the electrodes are nearest each other). The heat created by that arc makes it [the arc] travel up the gap between the electrodes until the gap is too wide for the arc to jump, thereby extinguishing the arc. Shortly thereafter, another arc forms at the bottom and the process repeats itself. You've probably seen a Jacob's ladder in sci-fi movies in the mad scientist's lab ...
Here's a link ... http://www.kronjaeger.com/hv/hv/exp/jacob/

zachtheterrible said:
The wires say that they are DC, will DC work with making a jacob's ladder?

The anode voltage (the big red wire) is DC... pulsed DC. You'll likely find that to use this flyback transformer, you'll need to supply it with several hundred volts to get it to do it's thing. As for the primary connections (the pins in a semicircle), you'll probably need some data on how they should be connected to get this thing to work. Maybe an automotive ignition coil would be easier to use? I don't know how much juice you'll get out of one of those though.
Perhaps someone would care to field that one?
JB
 
supply it with several hundred volts??? Well then how does it work while it is in the tv, is it already supplied with severalhunded volts? confused :roll:

Why would I not be able to simply hook up the red wire to one side and the ground to the other?
 
zachtheterrible said:
There are three wires coming out of it:
1. 40kvdc red wire, suction cupped to the crt.
2. 20kvdc white wire
3. 3kvdc white wire

The wires are actually:

1) EHT - about 25KV
2) Focus - variable, about 5-8KV
3) A1 - variable, about 500-1000V

The outputs of all these is DC, the transformer has the required smoothing capacitors internally - and the EHT is further smoothed by the capacitance of the CRT.

They operate at 15,625Hz (for 625 line TV), and the input is usually fed from around 150V DC, with a switching transistor pulsing it, the transformer is tuned (by external capacitors) to the correct frequency.

You would really need to examine the circuit of the TV, and use many more components from it.
 
I am a senior electronics student in high school and I first saw the idea of the jacob's ladder circuit on your post and immediately wanted to use it as my senior project. My electronics teacher told me I could do the project if I incorporated some digital aspects into the circuit. I am going to build a plexiglass frame around the ladder, and was thinking I could attach an alarm circuit that would be triggered by someone walking to close to the circuit while operating or someone lifting the plexiglass frame. I also had the idea of adding a switch that would be triggered by a clock timer circuit to shut on/off the circuit. Does anybody have any ideas as to ways I could go about these modifications. Also which would be cooler to use, a transformer from a neon sign, or an oil burner ignition transformer. I found an Oil burner ignition transformer that uses 14000Kv. Last what size transformer should I look for if I wanted to make a prototype.
 
I am not really planning on removing the transformer from the circuit for now. I would like to keep the transformer in the circuit so that i don't have to mess with anything else for right now.

So how do I do that?
 
zachtheterrible said:
I am not really planning on removing the transformer from the circuit for now. I would like to keep the transformer in the circuit so that i don't have to mess with anything else for right now.

So how do I do that?

You probably need to keep most of the TV circuit in place, it will all be controlled by a microcontroller and I2C bus - it will also have various safety shutdown circuits.
 
I just took the suction cup part off. There are two prongs. Do I just connect each prong to one side of the ladder?

As for safety devices Nigel, will they not let the ladder work?
 
no, the prongs inside cup that attaches to CRT are one terminal.
for jacobs ladder you need two (oposite polarity). connect it to ground.
 
As Nigel pointed out above, you are going to need alot of the other components from the TV chassis to make the transformer do what you want. There is a fair bit of circuitry used to drive the transformer, as well as some circuitry that detects and or corrects fault conditions.

You may find it easier to do a Jacobs ladder with a neon sign transformer, although it means buying one, or getting an old sign and transformer. A word of warning though... neon transformers can deliver substantial current... they bite back!
 
Eh Zach,
heres a photo of a kit you can get for a jacobs ladder. The project was in Sept 1995 in siliconchip but I dont have any issues that far back or I'd scan the article for you. But as you can see all you need is a automotive coil a few components and a car battery for power. Alternatively you could email siliconchip and pay $8.80 Oz for the project but hopefully someone has an old copy of the mag and can scan it for you.

Cheers Bryan1 :D
 

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Everybody keeps on saying that I'm going to need the circuittry from the TV. I know that! That's what I'm going to do, just conenct it up straight from the circuitboard :lol:

Eventually, I will probably get a neon sign transformer.

I think what Panic said is what I'm going to do. 25kvdc wire to one side, ground @ the other side.

Bryan, that jacob's ladder looks kind of small :lol: . I want a mains operated ladder so that it's bigger :twisted:

btw, is there anything that can be done to change the frequency, etc so that it does different things? I think this can be done with a tesla coil?
 
Here is My Jacobs Ladder. It is a bit over 3 feet tall and the transformer is a Neon Transformer, 15KV @ 60 mA. Much better than a Car Ignition coil.

I have another transformer rated at 125KV @ 150 mA. But I don't have Enough BIG Insulators to make a LARGE Jacobs Ladder for it. Its an X Ray transformer. Too Bad as it would make a Nifty Halloween Display.
 
SWEET! thats very cool chemelec :lol:

Well, I just plugged in the TV, and to my dismay, it doesn’t work. I know the fuse is fine because there is a large capacitor that will ‘pop’. The CRT doesn’t fire up, and I cannot get the speakers to come on, even if I turn up the volume. Any suggestions?
 
Andrew and Zach,

Forget the flyback transformer; it just doesn't deliver enough current.

Leigh Lundin used to custom engineer Jacob's ladders for Terror on Church Street Frankenstein display and other 'haunted' projects. He used oil burner transformers in the 10K-20Kv range for wallop, but for ToCS he switched over to neon transformers which delivered less juice, but could run for hours.

Tip: Use steel rods, not copper.
Tip: Shield the rods from air current.

Andrew, perhaps consider for your electronic project a circuit that cycles an oil burner transformer on for 2 minutes and then off again.

Remember, you're dealing with hi-heat, hi-voltage, and hi-current.
 
Need a Neon Transformer?, Ask me for Details.
But the Postage is Probably the Most Expensive.
 
Leve the dam TVs circutry rip it out! :evil:

also rip out the transformers pimary coil an wind your own one .10-15 thurns whith nice thick wire so you an run a lot of curent thru it.

search the net for an flyback driver.its an 2 transistor circuit.
 
There are lots of self-resonant circuits out there, I build one in college. IT used a couple of bipolars in TO-3 cases and you get to wrap your own primary and feedback windings on the core. Of course this means your transformer needs to have the core exposed.

It is way more effective than fixed frequency. It could draw about an inch of wonderful hissing arc, probably more in a Jacob's ladder where the arc gets to follow the heated, ionized gas.

I don't know if anybody mentioned this, but all flyback tranformers these days have diodes built into them, which kills its usefulness as a Jacob's ladder. It would be dicey to try to figure out how to drill it out or otherwise remove it. You really need to wait for Bulky Trash Pickup Day and look for grandma's older-than-moses TV to show up- the black-and-white era and early color ones usually had external diodes. They're obvious, it's located in the anode lead, about 2" long and the diameter of a pencil.
 
I still havent gotten that bloody TV fixed. I'm going to take it to my grandpa's house. he used to own his own TV repair shop.

Tom, when you say that I want high current from the flyback transformer, umm, I think you mean voltage? ideally, you want the highest voltage and lowest current.

chemelec, how much would you sell the neon sign transformer for? from what oznog said, the flyback transformer isn't all that great.

I'd like to do what you said electro, but I would have no idea how to connect the thing up. I searched like you said and found a couple of schematics and things, but I couldnt' find which lead to connect what to. There's like 8 leads of the transformer.
 
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