HV Ladder by Jacob

The Fremont Fry's has one of the better themes. It is supposed to be the "worlds fair". Lots of geeky displays like this. The other interesting theme is the Sunnyvale Fry's. They tried to make it an electronics museum of sorts.

For the actual shopping experience, the San Jose Fry's on Brokaw is where you want to go. Is is the most relevant as far as electronic components goes. As far as I can tell, it has the most of whatever Fry's carries.

Fry's used to be real jerks about cameras in their stores. They didn't want the look and feel of a Fry's to be duplicated. Nowadays with cellphone cameras, it is just impossible to enforce the no photography rule.

Back to the Jacob's ladder, if you can an off the shelf neon light display power supply, these things are trivial to build. All you need is the power supply, copper wire, and ceramic insulators.

Fifty eight dollars?? Impossible to believe so cheap.

nt

Try to get the 'old' transformer type, not the electronic ballast type.

From playing with one of these home-made Jacob's Ladders; I learned a lot about ESD. One example, I found that a very visible arc would strike through 3 sheets of paper, burning a hole and then traversing up the rods. However, no amount of insulation [a whole tablet of paper] would stop a slightly visible 'sizzle' arc to the metal head of a ball peen hammer held by its wooden handle....with the arc going just from one rod to the ball peen hammer's head with no need to complete the electrical path to the other rod. At the time this observation was a great marvel with no explanation.

Impossible. The current must complete the electrical path. Else you are violating the laws of physics. Something very quickly would become excessively charged creating a huge force of attraction and most likely create a _____(insert your favorite new age physics term here that will make you seem really smart. e.g., black hole, quantum singularity, etc...).

Chances there was a streamer or leakage that was not visible or the hammer was grounded in some way.

And had nothing whatsoever to do with ESD.

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OK, ESD is the dischage, not continual high voltage breaking down something. But, it is difficult to separate the two. But Jacob's Ladder is like an ESD with "Deep Pockets"

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I merely described the observation, and admit to very poor experimental controls.

I suspect the path was capacitive leakage in the transformer to earth ground, I'm holding the hammer with my hand standing on earth ground and that is the non-obvious closed path. Interestingly, I can feel voltages as low as 12V [DC feels like pin pricks into the skin and AC 'buzzes'], but did not notice anything while holding the hammer. Low current, really low current, must have ionized the air into visible spectrum of extreme blue.

I had not seen that shade of blue again until I looked through the quartz window into the oncoming beam of an ion implant machine (with reduced vacuum) - most beautiful pure blue.

WRONG AGAIN.

The are NO electrostatics going on here.

You experienced an HV discharge. Period. If there were some meat behind it, it would have been an HV discharge 'with sustained current' and you would not be here right now.

ESD relates to accumulated charges found on INSULATORS!

It has NOTHING to do with electrical power.

No, it is not. If you actually have a grasp of electronics, you would know the difference between electrostatic discharge and an electrical power fault event.

No, it isn't. It is a High Voltage AC arc on a vertically aligned, non-parallel pair of conductors. The heat of the arc causes it to rise, and the spread of the conductors means that it will eventually break, and reform again at the closely spaced bottom of the conductor pair.

It has NOTHING _at all_ to do with ESD.

It MIGHT be described as "Electrical discharge with deep pockets" if you actually had an understanding of it. I would never term it that way, but there is NO S (Static) in the ED (Electrical Discharge) here.

You also mess up "your" and "you're" too, don't you?

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substitute your for you're, yes ...also their and they're

in addition, live with dyslexia, niether form creates errors that are important, unless I'm writing 'copy'

The arc sustained onto the metal of the hammer was indeed like ESD. Each insulator in the path had enough conductivity that it would transfer excessive voltage gradient over to another something that could not sustain the voltage field and when that something insulator broke down the FULL voltage would transfer to another insulator and so on. just like ESD events.

What is missed by many is that in nature EVERYTHING conducts, even so called insulators. Keep that in mind and the analysis of just why ESD burned up the insulator placed there to stop discharges becomes clear. For example, during one project we were having discharges from the 20kV supply to a nearby corner of an adjacent structure [ground referenced]. One of the technical staff, in what seemed like a good solution, simply placed a 1/4 inch slab of PVC plate between the two discharge points. Then closed the box back up.

Later, as the full 20kV transferred to the surface then out to the edge where 1/4 inch absolutely could not sustain 20kV a resulting arc burned through the edge of the PCV, then proceeded to 'saw' a path down to the center at the shortest path between the two - 20kV source and structure; a fire started, Very dramatic failure caused by a lack of understanding of ESD.

Since you're dyslexic, I'm surprised you have such a low regard for the same trait in others. These mistakes make reading your text especially hard for fellow dyslexics. Maybe you don't care about others?

You appear to be confusing a number of different phenomena...

The insulated ball peen hammer head has a small amount of self-capacitance (a few pF). The nearby HV electrode sparks over to the hammer head on each half cycle, alternately charging its self-capacitance (through the conductive spark) during positive and negative HV half-cycles from the neon sign transformer (NST). While these low-energy discharges create significant radiated RF, they are not generally referred to as ESD. The current flowing through the small sparks is capacitive (displacement) current as electrical charge is transferred/removed from the self-capacitance of the isolated conductor. It is NOT due to leakage current through the hammer handle and your body

- a similar displacement current would flow even if you used an ideal insulator for the hammer handle.

Inserting an insulator in an air gap to prevent a HV arcing problem is a common error made by most HV novices. When the tech added the PVC spacer, he significantly increased the electrical field in the residual air spaces. This enhanced corona/streamer formation within the air gap(s). Unfortunately, he also worsened the problem by using PVC as the insulating material, since PVC performs very poorly as a HV dielectric in the presence of corona. The combination of UV and ozone from the corona discharges breaks down the nearby surfaces of the PVC, causing them to liberate hydrogen chloride which combines with water vapor in the air to deposit a partially conducting film of hydrochloric acid on ALL nearby surfaces. Under continued stress, the PVC surface quickly develops a carbonized track that grows over time, eventually connecting to the opposite HV electrode. The PVC and air gap then flash over, leading to an arc and smoky fire. The tech actually demonstrated a lack of understanding of electrostatics and the "dielectric circuit" of the system.

Bert

STOP making up stupid shit, boy!

ESD did not "burn up" ANYTHING (maybe your brain)!

Neat! Thanks for posting it.

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What do you mean low regard? When have I called anyone to task for dyslexic writing? Or, even for mispelled words, ...lately?

If you mean, "Why do you demonstrate low regard for other dyslexics by leaving errors in your postings?" in defense, before posting, I read, and reread, my postings looking for errors, both of spelling and dyslexic origins. When I don't see a single error, then post, only to discover after all the efforts that I still missed something! This PC system and usenet access have NO easily accessible spell checkers, so all checking is manual.

Amazingly, during the checking, an error [dyslexic word] appears to be absolutely correct, until it's noticed, then after that the error is always blatantly obvious, at least in that text..

On top of such personally generated errors, now the keyboard is aging and starting to skip letters. Leave out blanks etc.

You regard your readers, particularly those with similar problems, so lowly that you can't be bothered to use the right word. You should know better.

I'm specifically referring to "neither form creates errors that are important". You somehow think writing for others is unimportant. Why bother?

You don't have to tell me.

There is a difference between tupos and using the wrong words.

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y bother?

True, using the WRONG word will confuse ANYBODY, whether dyslexic, or not.

What was the wrong word?

Bert Hickman explained in great detail the EXACT process of deterioration. Sounded like he had been there, has the T-Shirt, etc.

same

"your" (instead of "you're")

An HV corona pierce through is NOT an ESD event. But YOU wouldn't know, ditz!