spark generator demo

So.... what "housing" would that be, then?

-- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.

And how did the wire sealing go?

Is it FCC compliant?

Would such a spark gap be considered an unintentional radiator or a transmitter? They were the basis of the earliest transmitters, right?

The new housing turned out to be a smaller PVC junction box that fits inside the larger one you see in the video. Originally, I thought the larger one had developed leaks either from the side or bottom, so removed the oil and cleaned it, then sealed the insides where I thought the leaks were coming from. What I really think happened though was that I didn't account for expansion of the mineral oil and it ended up seeping under the cover during hot periods. Anyway, the new, smaller box, should it leak, will be caught by the old that surrounds it for far less mess.

I ended up surrounding the HV exit wiring from the box with heavy duck tape, formed into a circle, and the wiring in the center. Then, I poured in epoxy to a depth of 1/2". That formed the new insulator and extra sealing. You can't see it in the video though as all that is shown are the HV wires coming through the larger containment PVC box and up alongside the electrode posts. It is only rated 40 KV TV wiring (like used for TV HV multipliers), so I have to keep my hands away or will get weakly sparked.

When I built the device years ago, it had the necessary filtering. In fact, when I showed this demo, it wasn't even removed from the shelving where I have it stored, and plugged in to the same strip that shares the desktop, monitors, and router. They all lie about 8 feet away from the device.

In

res

from

That being said, I would have *never* tried this feat with a Tesla coil I own. Actually, more of a "violet ray" generator-- a portable hand held Tesla coil to check for vacuum leaks and such or for demos. That one, I bought new. It would have greatly interfered plugged into the same outlet as everything else and only produces 2" sparks but at a much

higher frequency.

By the way, for the people who suggested retaining paraffin instead of going back to mineral oil, I am actually too curious to let that go! If

I can find two HEI coils at the junk yard for cheap, I am going to simply use an old tupperware or even dollar store container for housing,

and then use the stove and oven once again for paraffin potting. I'll be able to easily swap out my existing container for a wax filled one without having to build all new circuitry. So, if I hurry and pot it before it starts getting really cold here, I'll be able to see how it held up over winter when I check it out next summer. As I said before, where I have the demonstrator stored isn't under the best of climate control, so temps will range from upper 40's to high 80's depending on time of year.

I think your fears of the paraffin cracking are overstated. It is easy eno ugh to test without worrying about winter or potting another transformer. Just take a brick of wax and melt it in a container. Stick it in the freez

g to crack that should do it. If you want, cycle it every day by taking it out and putting it back in.

Did you have any other concerns with using wax?

BTW, there are other waxes than paraffin. You can use a higher melting tem perature wax which are often more flexible.

enough to test without worrying about winter or potting another transfor mer. Just take a brick of wax and melt it in a container. Stick it in t

it's going to crack that should do it. If you want, cycle it every day by taking it out and putting it back in.

Excellent idea and costs nothing to do since I still have the paraffin.

I was concerned about possible heating of the transformers within the wax and whether or not melting would occur. Not that I would run the device for long, maybe up to a min or two.

temperature wax which are often more flexible.

One of the last things I came across before going with the oil once again was "machinable wax" which evidently used a combination of paraffin and either HDPE or LDPE container material melted into it. I was contemplating trying to make some, but it looks like the PE would have had to been melted in something other than a double boiler. It did

offer a higher melting point though than standard paraffin. The ratio appeared to be 4:1 wax: PE. That would have meant 0.5 lbs of the PE for

my new housing which, to me, seemed like a lot of cut up containers!

Then there was the paraffin mixed with EVA glue, but I was unable to find a published proper mix ratio for that to work. I finally came across a candle making site that suggested 5%, but not very convincing for electronics.

Unfortunately, I didn't look much into other waxes other than beeswax mixed with rosin which, as I understand it, has an even lower melting point than just paraffin.

enough to test without worrying about winter or potting another transforme r. Just take a brick of wax and melt it in a container. Stick it in the f

going to crack that should do it. If you want, cycle it every day by takin g it out and putting it back in.

temperature wax which are often more flexible.

By containers, you mean milk bottles? Why would you buy containers? I don 't know if recycling centers will let you remove anything, but people use p lastic milk bottles by the ton. I have a collection used to make scoops an d funnels, etc. Funnels are like tape measures. It doesn't matter how man y you have, you can never find one when you need it. For dry stuff I make them from card stock.

I think the mixture thing is not the way to go. Paraffin has melting point

carbon counts between 20 and 40. More of the longer chains and the meltin g point goes up. Use alkanes with even more carbons and the melting point continues to increase and they become more pliable. Look for Microcrystall ine wax

s with carbon counts between 20 and 40. More of the longer chains and th e melting point goes up. Use alkanes with even more carbons and the melt ing point continues to increase and they become more pliable. Look for M icrocrystalline wax

Only possible issue I see using different higher melting point wax is whether or not it will melt in a double boiler, plus will the components

it is poured on/ into be able to take it? For now, I'm going to rest at

the mineral oil refilling and retain all the recycled paraffin from my attempt a week ago. I've discovered that the reason for the oil leaks from the former was because I filled it too high, so during hot periods oil seeped out from the top. I'm sure junction box tops were never meant to stop oil. I think my new one will probably leak too at some point from the top, but I'm using the larger older junction box as containment plus a resized absorbent pad underneath the smaller one for easy changing should it ever be needed in the future.

What would have been neat, and I never thought about it during the rehousing, was cutting out a section of one of the sides of the PVC junction box and replacing that section was plexiglass or lexan, so I, or whoever I am demonstrating the device to, can see where everything originates, but I thought that might simply be opening a can of worms (plexiglass to PVC sealing issues and such), so abandoned the idea.

I'll keep an eye out at the local junk yard for some more HEI coils. If

I can snag a pair cheap, I'll pot in paraffin and see how it holds up over time. Almost all of the circuitry is contained in the separate driver/ controller box, so really all I have to do is swap out the coils.