High Voltage

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rparrish
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High Voltage

Post by rparrish » Mon Dec 16, 2002 6:00 pm

Anyone else having problems with the Jacob's ladder? Have never worked with ignition transformers, do they require a I limit on the primary?

bwts
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Re: High Voltage

Post by bwts » Tue Dec 17, 2002 7:44 am

An ingition transformer? Is that off a neon light?<p>B
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Bob Scott
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Re: High Voltage

Post by Bob Scott » Tue Dec 17, 2002 8:35 am

Ignition coils are available in two different varieties. One kind has a resistor built into the primary to limit the current. The other type requires an external resistor. Either type is available at auto parts stores. They look identical.<p>Bob
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jollyrgr
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Re: High Voltage

Post by jollyrgr » Fri Dec 20, 2002 3:35 pm

I built one of these years ago when I was in high school. It didn't work that well either. What you might want to try, though, is the high energy type coil usually found in Racing or SPEED shops. The old "open frame" ignition coils from General Motors HEI spark systems are a good second choice. These were found on many GM cars and trucks from at least 1975 to 1990. These were the ignition coils that fit inside the distributer cap with the output pointing down to the rotor. Normal ignition coils (like the one pictured in the project) might top out at 30,000 volts. The GM coil put out around 60,000 volts.<p>Some of the early 90's (1991 to 1995) GM cars and trucks had a high energy external coil that looked like the one in the article.
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Re: High Voltage

Post by bodgy » Sat Dec 21, 2002 2:34 pm

Where is good old Mr Van de Graph when he's needed?<p>
bodgy<p>
Oh yes the amount of humidity in the air will have some bearing on how good a spark occurs.<p>Now lets all make a Leyden Jar.
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Chris Smith
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Re: High Voltage

Post by Chris Smith » Sat Dec 21, 2002 7:13 pm

Your age and dust are showing, bodg?

bodgy
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Re: High Voltage

Post by bodgy » Sat Dec 21, 2002 9:55 pm

Just call me Faraday - or was that something to do with Charlies Angels?<p>And you Chris could be well, Franklin or Lee de Forest.<p>
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Chris Smith
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Re: High Voltage

Post by Chris Smith » Sat Dec 21, 2002 10:48 pm

Shhh, it make me feel old just thinking about it?

amorfesi
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Re: High Voltage

Post by amorfesi » Sun Dec 22, 2002 7:32 pm

I got one going! Took a few slight alterations to the original circuit. I wanted to use an in the wall power supply. Got one from the place recommended in original article. It was capiable of one amp! Redrew the circuit to use two 555's since that was what was on hand. Started with very weak spark. Positioning of wires is critical.
Circuit appears to draw 950 mA at peak measured on an HP current meter. Supply was collasping for the IC's
Split out Vcc to IC's with a diode and put a storage cap in to keep them about ten volts.
Hardwired vcc directly to + coil with additional capacitance. Ran seperate return to supply ground and Q2. These mods allowed for greater isolation and shorter current paths for supply and ground. Also the additional capacitance supplimented the current supply to the coil and kept the supply from collasping by providing on demand current.
Spark now is jumping 1/2 an inch and traveling the full length of the wires.
This is with a standard ignition coil. (Yes those suckers are a lot more expensive now than they were a few years ago.)
Spark went from a weak blue to a solid purple, after the mods, with a beautiful yellow/white arc on one electrode.
Q2 definitly getting warm like was suggested in the article. Heat sink with fan definitly! I will experiment later on paralleling two n chanel mosfets to split the current load. I am also going to find out if I can still get a fet in a T03 package.
Awesome project!!!!!! Everyone I have shown this thing to wants to build their own!
Note: This is what I did and I would be willing to say that that the rapid discharge from the capacitor is sourcing more current than what the supply on it's own could. Great care should be taken if this mod is done due to an increase in current available from the capcitor.
I can't wait until the next "mad scientist" project from Nuts and Volts!

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Re: High Voltage

Post by analogee » Sun Dec 22, 2002 7:38 pm

Just built it tonight, and I get an arc, but it doesn't travel. Moving the rods affects where the arc decides to reside, but doesn't seem to make it want to move. Anyone else solve this problem?<p>I think maybe the arc is not lasting long enough in my circuit. How long are peoples 'on' times (I guess "dwell" would be an appropriate term)?
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HomeBrew
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Re: High Voltage

Post by HomeBrew » Sun Dec 22, 2002 11:38 pm

I used an old surplus neon sign transformer(10kv)and it worked very well ,with a couple of of coat-hangers that I had on hand. No. 10 or 12 guage bare copper wire also did a good job.

amorfesi
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Re: High Voltage

Post by amorfesi » Wed Dec 25, 2002 4:40 pm

One thing I neglected to mention is that I am using 14 Ga copper wire for mine.
After doing the changes I suggested in my earlier post. It works very well. One may have to adjust the chopper trimmer. The arc travels the full length of the wires.

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dacflyer
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Re: High Voltage

Post by dacflyer » Sat Dec 28, 2002 11:01 am

these are so simple !... i have been into HV for a long time...
easiest one i built was when i was 11...
i used a "francformer" brand.and most common of all weatherproof transformers...usually used in outdoor neon signs...this was a 9,000v / 30ma
transformer...it had the input on one end and the HV on the other,,next to each other...
i made the ladder out of heavy 10ga or was it 8ga
copper...easily gotten from electrical supply,
bare gnd copper.
i made the ladder with 3/4" gap at bottom, and adjuster the top gap to get a full climp to the top , humidity does not effect this thing as it has pleanty of current,,,but wind does effect it,, if you build have wind pooblems,then build a case for it,,,but do have vent holes in the bottom,,,and the top completely open,,,cause the electric flame can ignite stuff instantly !
good luck...want more info contact [email protected]

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Re: High Voltage

Post by skrallman » Tue Jan 07, 2003 9:13 pm

I didn't realize this topic was about the Jacob's Ladder. I posted this same question in the "Jacob's ladder pcb" topic.
I've made the circuit on a proto board, but I can't get it to work for more than a few seconds. I get a solid spark and it travels. After about 5 to 10 seconds the 556 or the MOSFET, or both die.
I'm wondering if there are some high voltage spikes taking them out?
I'm going to put the timer and the coil on different power supplies, with a common ground.
Any opinions about a capacitor between the timers positve supply and ground and capacitors from the control pins (which aren't connected) to ground? Maybe a varistor?
I've been through four 556's and MOSFET's.
Scott

skrallman
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Re: High Voltage

Post by skrallman » Tue Jan 07, 2003 11:04 pm

Well, I can answer my own question. I put the timer and coil on separate power supplies, put a cap across the timer's power and ground and put a varistor across the MOSFET. It works. I was down to my last timer, so I tried everything.
I'm getting a good spark that jumps about 1/4in, but it will only travel up the rods about a 1/2in. Has anyone got it to travel the whole 5 or 6 inches of the rods?
Scott

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