They’re affecting their effect there.

J/P=?

Thank you. After reading through that I’m much relieved. I’m sure that video was edited for maximum viewer impact and not as a documentation on your equipment and procedures, because none of that caution comes through on the video.

As a little background on myself, I’ve spent the past 20 years or so on and off in the semiconductor equipment industry, including eight years at Applied Materials. I worked on etch chambers that not only had multi-kilowatt RF generators, but high pressure air operated devices and used some of the deadliest gasses known to science (silane, anyone?). It wasn’t enough to have safety pounded into us enough on a daily basis, we also had to take an annual “hazmat” training class to have the fear of death re-instilled in case we’d slacked off.

In addition to that, I help run the largest model rocket club in the country, and have to oversee the safety of launches where we send 200 to 300 rockets skyward during a four hour launch. Procedure is everything.

Thanks for the clarification,

- Jack

Thank you. I really shouldn’t try to do that in my head! I always drop an exponent somewhere. I had 1F equaling 1,000,000 uF (which is true), but I used the “million” instead of the “one” when multiplying out the energy.

I was also going to point out that at 12V it didn’t pose a lethal hazard, although it can give you a nasty burn across your fingers. Plus we discharge it a lot slower. Our firing leads are 14 ga and they mention 12 ga, plus it’s about 15 feet of cable from the firing relay to the ignitor clips compared to a few inches for their setup. We probably have at least an order of magnitude more resistance in the discharge path (if you include the ~1 ohm in the ignitor itself).

That still doesn’t excuse them for their shoddy safety practices.

- Jack

Well, the “does the coin melt?” question seems ripe for an episode.

There are some non-obvious safety systems in place which don’t make it into the video.

- Before operation, a safety perimeter is established keeping personnel at a safe distance.

- The chamber which contains the coil has been tested hundreds of times. HDPE turns out to be one of the few materials which are up to the task of absorbing the shockwave and shrapnel. In addition, the walls are made out of nearly 2 inches of the stuff, and built way over spec. The shrapnel penetration depth is less than 1/4 inch into HDPE.

- the 2ndary spark you see emits UV, however, all staff are wearing UV blocking safety glasses, in addition to earplugs. 132db is quite loud.

- The operation of the chamber is as follows: Clear the area, Unsafe it, Charge it, discharge it, remove the balance of the charge (about 1kv normally), safe it. If any time during this cycle one of the spotters sees someone enter the danger zone, the operation is stopped. Keep in mind that after a charge is put into the cap bank, it is in a very dangerous state. The only way to safe it would be to discharge it.

- Regarding the tubing in use on the trigger: Best practices require a simple explanation of safety. The mechanical triggers, while ‘crude’ can be easily inspected for proper operation, and their safety level and function can be determined at a glance. This was a design requirement which I believe we implemented very well.

- Use of high voltage gloves – we are dealing with 10kv DC charge. high voltage gloves have many failure modes, and our safety policy demands that we simply do not interact with the device while it has a charge. Honestly, even if you had gloves, a bump of the elbow would likely cause death anyway, so they provide very limited protection.

- The operators of this device have practiced handling failure modes – the only real tricky one is if the bank has a charge and we don’t have a way to discharge it. The yellow 2ndary switch, if it fails, still has exposed contacts. We have a method for manually safely discharging the bank remotely should our safety switch fail.

If you have any further questions, please don’t hesitate to ask. you can email me at 3ricj ATTY hackerbotlabs DOTTY com

As for mythbusters, I have not seen any of their work, but we built stuff for ourselves, not for TV. Thanks for watching.

Thanks!

As far as X-rays go, just a reminder that Scotch tape peeled in a vacuum can create X-rays, Lightning also generates them.

Where’s Adam and Jamie? I’d love to see Mythbusters lash together a setup like this.

Can anyone formulate a “myth” around this for them to bust?

4. Psychology. feeling or emotion.
5. Psychiatry. an expressed or observed emotional response: Restricted, flat, or blunted affect may be a symptom of mental illness, especially schizophrenia.
6. Obsolete. affection; passion; sensation; inclination; inward disposition or feeling.

effect –noun

1. something that is produced by an agency or cause; result; consequence: Exposure to the sun had the effect of toughening his skin.
2. power to produce results; efficacy; force; validity; influence: His protest had no effect.
3. the state of being effective or operative; operation or execution; accomplishment or fulfillment: to bring a plan into effect.
4. a mental or emotional impression produced, as by a painting or a speech.
5. meaning or sense; purpose or intention: She disapproved of the proposal and wrote to that effect.
6. the making of a desired impression: We had the feeling that the big, expensive car was only for effect.
7. an illusory phenomenon: a three-dimensional effect.
8. a real phenomenon (usually named for its discoverer): the Doppler effect.
9. special effects.
–verb (used with object)
10. to produce as an effect; bring about; accomplish; make happen: The new machines finally effected the transition to computerized accounting last spring.

affect –verb (used with object)

1. to act on; produce an effect or change in: Cold weather affected the crops.
2. to impress the mind or move the feelings of: The music affected him deeply.
3. (of pain, disease, etc.) to attack or lay hold of.
–noun
4. Psychology. feeling or emotion.
5. Psychiatry. an expressed or observed emotional response: Restricted, flat, or blunted affect may be a symptom of mental illness, especially schizophrenia.
6. Obsolete. affection; passion; sensation; inclination; inward disposition or feeling.

Your arithmetic needs repair. a 1F capacitor at 12V holds (1/2) * 1 * 12*12 = (1/2) * 144 = 72J.

The capacitors in this demo held (1/2) * (300 * 10^-6) * (10^4) * (10^4) = (1/2) * (3 * 10^-4) * 10^8
= (1/2) * 3 * 10^4 J = 1.5 * 10^4 J = 15,000J.

This latter is clearly a few order of magnitudes more energy. Further, if you try to discharge your 1F
capacitor through yourself, you won’t notice it — the voltage is insufficient to drive any current unless
you short it with a low-impedance path. That’s definitely not true of the 300 microfarad setup.

/es

Hmmm, or maybe something that opens up the circuit (for precautions) like in thermal fuses. Though I have to admit, this is a bit far-fetched.

David Barksdale’s (name) link may provide a clue to your question, “does anyone know what that secondary string pull was?…”

Here is the link from Hackerbot Labs (my guess is it opens up the high-density plastic blast chamber):
http://www.hackerbotlabs.com/2009/03/coin-shrinker/

~~~~~
The link has answered my question as well @ #41.

Where Does The Coin Go?

No material is lost from the original coin: the weight and volume are the same as the original. But the coin now has a smaller diameter and is thicker, while retaining much of its surface detail. It’s also extremely hot just after firing!

Hmmm, no wonder the coin appears puffy.

Plus, does anyone know what that secondary string pull was? After the bang, the guy closest to the camera says something like “wait for this” then pulls some sort of yellow block out of the chamber.

Also, the amount of energy stored in a capacitor, IIRC, is 1/2 CV^2. That agrees with their assertion of 15,000 J using a 300uF cap working at 10,000V. While that’s enough to kill you, I should note that our club’s launch equipment uses a 1 F capacitor (that right, one F, not “micro”) working at 12 volts. That works out to 72 MJ or nearly 5,000 times the energy in their setup. We verify that everyone is clear to a radius of about 100 feet before we start charging it.

- Jack

A lot more than in those caps. We’ve got a machine here in Livermore to do that, about two miles down the road from me, that’s about to go online. It’s 30 m in diameter and consumes gigawatts for the nanoseconds that it’s turned on. Oh yeah, it uses lasers. They tried magnets, but it didn’t work.

————————————-
24. mike Says: “I believe quarters are silver plated copper. Silver melts at less than 1000 C, copper around 1100 C. Not hot enough to glow visibly.”

Actually, I think they’re aluminum/copper, and it’s not just a plating. It’s three roughly equal sheets sandwiched before being punched and stamped. Aluminum also melts well before it starts to glow.

—————————————
For my own comment, I have to say I wasn’t terribly impressed with this. I’m sure these guys are very bright, but they’re a few tacos short of a combo plate when it comes to safety. They’re playing with some significant energies here (note the “risk of death” sign) but the equipment looks very crude. The primary switch is some SiC contacts in G10 brought together with a large rubber band? Oy! No one was wearing any sort of PPE (Personal Protective Equipment). At a minimum they should be wearing UV filtering lab goggles, but a face shield would be better. The people working around the high current pieces should have had insulating gloves. The guy who hollered “Look away!” didn’t wait very long before pulling the string. No one was confirming that they were looking away before the string was pulled.

Cripes, even model rocketry has better safety procedures than this. We’re REQUIRED to use electrical ignition that can be stopped up to the last second if an unsafe condition pops up. We’re REQUIRED to make a loud announcement of impending launch and we’re REQUIRED to verify that everyone within the hazardous zone is aware of what’s about to happen before the button is pushed.

Some people depend too much on luck.

- Jack

Alternate scenario: The guy in the black suit dons a pair of dark glasses and says, “Now watch this carefully…”

Obviously if you keep heating it, it will melt. In my business, that would be a bad thing…

Wouldn’t the metal compress? I don’t know, being a jeweler and not a scientist, but that seems likely to me. The copper center would surely compress… I’ve fired copper in a kiln to 2,000 F and it degrades and comes out with holes in it. Seems like there’s “room” in the metal.

Looking at the video, it felt like I was looking at a star collapse.

Either way — this is freakin’ cool. The sign on the front of the machine is pretty cool, too, as is the description of the power output. A one pound ball, two miles high? How far could it then send, say, a 1 ounce ball at a 45 degree angle (altitude) assuming no atmospheric drag?

I don’t think so. The coin wasn’t fraudulently altered.

@mus: Feynman was pretty far from the bomb and wouldn’t have received a large enough dose to instantly ruin his eyes. On top of that, people in the bunkers were told not to look directly at the initial flash of light (but you can use any number of tricks to view the initial flash). The car windscreen doesn’t really block all that much UV (well, it also depends on what frequency UV). You can still get a good UV sunburn while sitting in your car. I can’t remember which book Feynman describes the experience in, but he was a bit of a nut so I wouldn’t be surprised if he took risks. I do recall that he liked to say that others missed a lot because they were looking through such dark glasses, but I can’t remember if he dared to stare at that first flash.