Tesla coils-

[RotogenRay]

It seems like people consider 'coilers' (as they call themselves) a bit more low brow in their choice of hobby than those who pursue real equipment such as amplifiers and receivers or any such contrivance which actually preforms what you all might consider a useful function. I suppose the use is defined by the user.

It is not completely inaccurate to think of some such people, coilers, as those who might have gone on to some more respectable venture had they been trained properly and gotten past a fixation with drawing arcs from transformers and producing copious amounts of ozone from their tesla coils. Some progress, but many friends I've had eventually lost interest altogether.

I'm sure many of you might have built a tesla coil in previous years.
Perhaps you have a story to share?

Tesla coil builders fancy themselves as experimenters. Generally, they progress to the level of 'tinkerer' and not much further toward experimenter. I speak of course, of those who build out of found parts and instructions found on the internet. And there was a time when I was young and didn't know a thing about building tesla coils, radio, or much about electricity in general.

http://4hv.org/news.php

There are those hams that enjoy this hobby, but somehow, we seem different than those who would prefer to be on the air or fixing something.

I digress, how did you get to the place you are at today? Was a tesla coil responsible for some part of your experience?


Pic related: my spark gap tesla coil november 2006 or 7

[N3DRB The Derb]

nope, no tesla experience here. I dig radio.

[ka3zlr]

I much rather rebuild some things from the past once in a while, maybe build a new rig..listen to the latest...happenings..an I also like Microwave and VHF/UHF...So..hey..Digital's fun too...AM is Kewl....so..

It's a Great hobby Electronics...Lots to do...

73
Jack.

 

[WB2YGF]

No Tesla coil experience here.  The high voltage supplies we manufacture at my work are based on Cockroft-Walton voltage multipliers. I once saw one of our 500 kV, 1 kW DC power supplies throw a fabulous arc. 

[Ed/KB1HYS]

I did build a Tesla coil, used a 15KV Neon sign tranny and home brewed a flat plate pulse discharge cap for it.

Ran 18-24 inch discharges on a good day.  Had a catastrophic failure of the cap (internal arcing) due to a really bad tuning episode trying to go further ( more power Mr Scot!!).  Anyway the salt water caps were disappointing but pretty, and would flash over badly. Was impressive but not desired.  Lost interest as I lost the time to mess with it. 

Had always been a SWL, and one day picked up a valiant in a scrap heap.  Got the bug when I heard a fellow in "Ripley Ohio" calling CQ (he was a nice am signal) and I couldn't answer him as I wasn't licensed.
That was it...

Still have the coiling stuff, incase I get the bug i guess.

Also built a couple of Farnsworth Fusors too...  but that is another story.

[k4kyv]

I remember taking my kid to a travelling tesla coil show when he was about 7.  The guy put on a spectacular demonstration with his rotary spark gap outfit.  It  worked very similarly to a Titanic-era spark transmitter.  I asked the guy if he had ever considered using a transmitting tube oscillator (something like an 833A) instead of the spark gap.  He claimed he could get more output and a more spectacular display with the spark outfit. 

[Todd, KA1KAQ]

I was always more of a Jacob's Ladder type myself. Still plan to build one, someday. Though a Tesla coil would be nice, my luck has been pushed far enough already with transmitters of the half-ton and larger variety.

Curious, though.....

such people, coilers,

...would that make us.......hammers? 

[RotogenRay]

Also built a couple of Farnsworth Fusors too...  but that is another story.

extremely relevant to my interests

[W9GT]

Ed..

I, also would be interested in hearing more details about the Farnsworth Fusor experiments.  I grew-up within a few blocks of Farnsworth's home and I have always had an interest in him and his work.  I enjoyed?? the QRN created by some of his experiments on the 40 M novice band when I was a young novice in 1959-60.

73,  Jack, W9GT

[RotogenRay]

No Tesla coil experience here.  The high voltage supplies we manufacture at my work are based on Cockroft-Walton voltage multipliers. I once saw one of our 500 kV, 1 kW DC power supplies throw a fabulous arc. 

That would be the REAL lightning maker

[Carl WA1KPD]

Todd
Here is a Jacob's Ladder I threw together about 3 years ago.
Simple neon xfrmr, push switch and some brass rod. Took about an hour

Kind of fun

Look forward to seeing you at Nearfest!

Carl

/KPD

[Pete, WA2CWA]

Back when I was a junior in high school, a friend and I built a four foot high Tesla coil in his basement . We begged a HV transformer (I think they were around 10 or 12 KV) from the local oil furnace servicing company. For a spark gap, we used large nail spikes secured through some blocks of wood, built a large capacitor with a pain of window glass and a sheet of aluminum foil on both sides. The secondary coil was wound on a non conducting form (I don't remember what we used) in my friend's father's shop where he worked in Long Island City, NY. He actually carted the finished coil through the subway and train home to NJ. The primary coil was fabricated using a number of wooden dowels connected to circular end pieces that could be moved and set in place anywhere along the secondary coil. We used an old copper toilet bowl float at the top of the secondary coil. We fired this thing up in his basement and had corona discharge to almost every pipe in the basement and every nail in the floor above us. The smell of ozone was everywhere very quickly. We lit every florescent light fixture in the three story house. We also lit, I was told, florescent light fixtures in a number of houses in the nearby neighborhood. All radio and TV reception were totally disrupted in his neighborhood when we fired this thing up. As the glass/foil capacitor charged and discharged, you could actually see the foil flexing on the glass. From what I remember, the audible noise this thing generated was deafening. Unfortunately, we had to dismantle the entire apparatus within a day or two, on orders from my friend's father, after the local police were called by the neighbors to solved the mystery of all the radio/TV interference and all the erratic florescent lighting. Friend's father wasn't really sure that we were doing with the homemade apparatus, since we fired this thing up when the parents were at work. We felt is was in our best interest not to show his father what we created. After we dismantled it, we tried to talk our high school physics teacher into letting us rebuild it in the physics lab but he had safety and management concerns so it never was done. Senior year soon came along and Tesla coils became less important activities.

[Ed - N3LHB]

I built one in my junior year in high school. Used a cardboard 4 inch form with number 32 as the secondary. I remember it taking 2 nights to wind the secondary with a single layer. Primary was about 20 or so turns on a wooden form located at the base of the secondary. Used a 15kv neon transformer for excitation, and multiple glass TV picture tube 1/4 inch panels (older TV's had a protective glass plate in front of the CRT) and aluminum foil for the condenser. First time I fired it up, I was getting 18 inch discharges easily.
I remember firing it up one time to show off to some high school friends, but it didn't seem to have much action... I then smelled what seemed to be an awful smell, thought geez, someone has some smelly farts. Later, I discovered that my homebrew capacitor was burning through the carpet into the concrete. Later that evening I found about a 1 inch hole burned through the carpet and thanked my lucky stars that I didn't burn the house down.
Sold the Tesla to one of my buddies who's father owned a TV sale and repair shop. He invited me back into the repair area one night and demo'ed his handywork. It was sitting on a workbench and he cheerfully fired it up. Arcs were shooting everywhere, including right into the wall and hitting who knows what. I still wonder why that place never burned down.   

[Ed/KB1HYS]

I built two fusors, both low power one using 10kv on the grid and the second later version using only 15kv. 

The first was built inside a discarded turbomolecular pump housing (I worked at a place that repaired them and got it as scrap) that was spherical with end bells. The grid was 0.02 inch stainless steel wire, formed into a 3 inch globe.  I borrowed a 10kv DC lab supply from one of the mass-spectrometer guys and used that to power the system.  Pumped it with a two stage mechanical pump and got reasonable pressure.  The grid geometry on this one was flawed as I had some ion recirculation going on, evidenced by a plasma "bugle" comming out of one of the apertures in the grid.  I fed it helium through a calibrated leak.  Never really got a good plasma containment out of it, as the grid design was lousy - too big for the power available, and the spacing between the housing and grid was small.

The second one I build in a 12inch bell jar, that I had also been using for some High Vacuum stuff (I had made an x-ray tube in it, but got a little worried when the gieger counter was clicking a few feet away and stopped that line of investigation)
The second design used a smaller grid diameter, ~2 inches with a much more uniform grid. same wire size. I also used the 15KV transformer for the power supply so there was more voltage available.   This one produced a fine, white plasma that had the classic star appearance.  I ran it on AC as well as DC and found that it would at 60hz and I didn't have to worry about zorching the rectifier stacks. The DC supply was just a half wave using salt water caps. Not great filtering there anyway as the cap value was small.

There were other things I wanted to persue, I wanted to see if a pulsed field could compress the plasma further than the fixed DC fields I had been using. Along that line I wanted to try an RF power source that I could tune to get a resonant plasma containment field.  The other was to construct a good size Van DeGraff generator and use that as a source of pulsed High Voltage, which in theory could have provided >100kv pulses controled via a spark gap setting to change frequency of the pulses.

I still have a lot of the equipment, awaiting the day...

[RotogenRay]

I built two fusors, both low power one using 10kv on the grid and the second later version using only 15kv. 

The first was built inside a discarded turbomolecular pump housing (I worked at a place that repaired them and got it as scrap) that was spherical with end bells. The grid was 0.02 inch stainless steel wire, formed into a 3 inch globe.  I borrowed a 10kv DC lab supply from one of the mass-spectrometer guys and used that to power the system.  Pumped it with a two stage mechanical pump and got reasonable pressure.  The grid geometry on this one was flawed as I had some ion recirculation going on, evidenced by a plasma "bugle" comming out of one of the apertures in the grid.  I fed it helium through a calibrated leak.  Never really got a good plasma containment out of it, as the grid design was lousy - too big for the power available, and the spacing between the housing and grid was small.

The second one I build in a 12inch bell jar, that I had also been using for some High Vacuum stuff (I had made an x-ray tube in it, but got a little worried when the gieger counter was clicking a few feet away and stopped that line of investigation)
The second design used a smaller grid diameter, ~2 inches with a much more uniform grid. same wire size. I also used the 15KV transformer for the power supply so there was more voltage available.   This one produced a fine, white plasma that had the classic star appearance.  I ran it on AC as well as DC and found that it would at 60hz and I didn't have to worry about zorching the rectifier stacks. The DC supply was just a half wave using salt water caps. Not great filtering there anyway as the cap value was small.

There were other things I wanted to persue, I wanted to see if a pulsed field could compress the plasma further than the fixed DC fields I had been using. Along that line I wanted to try an RF power source that I could tune to get a resonant plasma containment field.  The other was to construct a good size Van DeGraff generator and use that as a source of pulsed High Voltage, which in theory could have provided >100kv pulses controled via a spark gap setting to change frequency of the pulses.

I still have a lot of the equipment, awaiting the day...

Wow, you're the real deal...

Physics is really my passion (especially high energy and plasma physics) but I've been stuck bumping around in the dark with microwave transformers and homebrew stuff. I've only recently (like in the past year or two) started working with tubes..

I gave Opcom a truckload of resistors I rescued, and he said "Are you sure you want to give me ALL of them? Won't you need some?" to which I responded "I don't really use resistors.."

To which I believe, he chuckled.

But I digress, I've been looking for some way to pump enough air out of a container so that I can start doing things like generate x-rays and do plasma physics experiments or build tubes or magnetrons... just experiment.

But I haven't been able to find any adequate vacuum pump... not to mention that since I lack any real experience I don't have much of an idea of what I'm doing.

I have some friends who built replications of "tesla bulbs"


Its supposedly the propulsion mechanism of UFOs... Which are supposedly all man made and pioneered by Tesla himself.

In any case, heres some neat pictures of the bulbs.

[Ed/KB1HYS]

those tubes are neat. look like giesler tubes.  Neon or Xenon plasma (or other gasses/mixes).  Pretty to look at.

As for vacuum pumps, if you just need 10^-3 torr say for plasma or fusor work, you can jimmy up an old compressor. Evil Bay also has rotary vane type pumps usually pretty cheap. Avoid Diaphram jobs as they won't usually get the pressure you need.   At those pressures and pumping speeds you can use Home depot plumbing stuff to valve and plumbing. If you go to High Vac stuff that just wont do, outgassing will mess up everthing, let alone leaks.

If you want to generate X-rays you need a high vacuum, and will need a molecular pump, like a diffusion pump (probably the cheapest), cryo, ION or if you got cash a turbomolecular job (expensive and when they break the self destruct!!).   Used diffpumps are cheap, just make sure they use something not to toxic as a fluid. Older ones used mercury vapor as the pumping media. Probalby couldn't get the Hg to run it. New ones use a synthetic ester oil (Not cheap) but you only need a quart for a lifetime of pumping.

You will also want a method to monitor the X-ray output, and SHIELDING lead flashing works ok as long as your Ev is low like under 50kv.   Be carefull, X-rays, comsic rays and Gamma rays are all essentially the same thing just how much energy is used in their creation, and I guess the source.

Last and Firstly BE SAFE all this stuff can get you in a lot of ways. Be Carefull!!

[Ott]

This experimenter used a 4-1000 at 60kv to x-ray the whole house...



"A GM (Geiger-Müller) counter placed near the tube immediately displays an overflow. Since this might be bad for my health, I decide to turn the power off. Next, I operate the HV transformer with a remote-controlled switch from the adjacent room. Even behind a 20cm (0.7 ft) stone wall, the counter shows about twice the normal background radiation. Without shielding, the counter sounds like a machine gun even at a distance of 10 m (33 ft) from the tube. A thick wooden door or a piece of sheet aluminum put between tube and counter does not make much of a difference. Although I used to work with X-rays when I was at the university many years ago, I am still fascinated, and I get a feeling of what W C Röntgen must have thought when he discovered this kind of radiation in 1895."

More here:

http://www.celnav.de/hv/hv2.htm

Interesting stuff...

[KL7OF]

This experimenter used a 4-1000 at 60kv to x-ray the whole house...



Whoa!!

[Ed/KB1HYS]

I just hope it had something wrong with it. Hate to see a 4-1000 go to waste like that...

[Opcom]

Wonder what a defective 673 would look like in the place of the x-ray 4-1000? Roentgen ray, you want to find out?

[Ed/KB1HYS]

Looks cool as all get out...

[RotogenRay]

Wonder what a defective 673 would look like in the place of the x-ray 4-1000? Roentgen ray, you want to find out?

Yes

And I'm the guy thats just crazy enough to try it.

[w4bfs]

I just hope it had something wrong with it. Hate to see a 4-1000 go to waste like that...

have you ever seen a target of a used xray tube ? .... severe ablation is evident .... with 60 kV as accelerating voltage, you certainly are approaching relativistic velocities and will erode whatever is + target ... dangerous    73   John

[RotogenRay]

have you ever seen a target of a used xray tube ? .... severe ablation is evident .... with 60 kV as accelerating voltage, you certainly are approaching relativistic velocities and will erode whatever is + target ... dangerous    73   John

relativistic velocities... 250kv is about 50% the speed of light for an electron. This is evidenced by its mass doubling at that speed. But of course it's on a curve...

and most of the output from an x-ray tube is heat, which is what damages the target.