Looking for conductive cloth.
Need small quantity. Needs to be very flexible. Needs to have a cloth i.e. non-conductive (cotton, poly etc) surface on both sides. Needs to shield against RF.
Where can I find it?
Tap Plastics stocks carbon fiber, but I don't think it is as suitable as the cloth in the link above.
Mark wrote in news:khu9hm$r16$ snipped-for-privacy@dont-email.me:
Buy silver or goldlaced cloth.
From vague memory, there is a medical product development company owned by a French company that one time designed a flexible pullover type shirt with inbedded conductors. They might pass on the name of the company that made the prototype shirts.
try contacting Bob Stone 408 684 5110 Tronics MedTech, Inc.
1525 McCarthy Blvd., Suite 212 Milpitas, CA 95035 Tel: 408 541 1212 Fax: 408 541 1763 info AT tronicsmedtech.comBeing an EMC Expert, I don't think you'll get the type of shielding you want, you could try firms that make flexible EMC shielding, but those products are pretty metallic.
There is a company that makes 'home' products, and from memory may sell clothing specifically designed for shielding. Again from memory, ELF shielding. I just did a search in my data base and since can't remember their name, can't find it!
Let me know if you want their name, and I'll make an effort to knock cobwebs off brain and find for you..
Small quantity = sample!
--
John Larkin Highland Technology Inc
Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
can be sure that someone like these will sell something:
;)
-Lassse
n
Wow, an RF protecting hat, someone's making money from the tin foil hat! (I liked the pic of the office with RF protecting fabric... and all the computer gear on the desk.)
Fun, George H.
Is that a quantity of less than one?
How flexible? Does it need to stretch? If not, something like aluminum window screening, sandwiched between two layers of ordinary cloth, might work. If that's too stiff, just find someone that can do rubber calendaring (screening) over the aluminum window screen.
It will be interesting to see how you make an electrical connection to the shielding through the cloth.
At what frequency? How much attenuation do you require? Any FCC, IEC, etc specs involved?
Dunno, but I've had to wear RF protective overalls when climbing radio towers. I've seen two types of material. One is an aluminized mylar sheet glued to the outside of ordinary cloth. The other has a mesh of fine sliver wires woven into the material. You might ask the vendors of such overalls where they buy their material. The overalls were a bit on the heavy side but quite comfortable. The fully metalized version was like wearing a sauna, which also stored the body odors of the previous occupants.
There are also vendors that sell to the RF paranoia and electrosensitive market what sells everything from RF shielded underwear to "drag as you walk" grounding anchors:
If you can't find anything, send me an email and I'll ask my former friends in the Smog Angeles garment district if they have a source. Although my fathers business was making lingerie, we also did some heavy metal clothing, which might qualify.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
I wonder if the electrostatic jackets and lab coats would work? Anyone know?
There is no electrical connection. It is to be used as a barrier surrounding a sensitive device.
It's easy enough to test. Fire up your cell phone, wireless PDA, or cordless phone, and see if you can make a call or connection while wearing an anti-static lab coat over your head. When you're done feeling foolish about this test, you might consider that the typical conductivity of an antistatic sheet is in the hundreds of kilo ohms per square, while that of a wire mesh RF shield is in factions of an ohm per square.
Agreed. There is also no logical, philosophical, or moral connection.
Hint: The world of RF materials is divided between conductors, reflectors, and absorbers. In this case, the last thing you want is a conductor or reflector. At best, these will take your unspecified RF source, and bounce the signal around your unspecified sensitive device, going in directions unknown. Reflectors do not diminish the signal very much, were you can easily end up with a stronger RF signal in places. On the other foot, absorbers convert the RF into heat, which is not going to affect your unspecified sensitive device, and will not reflect all over the unspecified surroundings. When you're done trying to make a reflector or conductor work, think about using an absorber.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
saran wrap
reynolds wrap
saran wrap
Available at your grocery store. You might also find something suitable in a smaller quantity by ordering a hot sandwich (foil-paper composite and add a napkin.) Depending how small a quantity you need, gum, chocolate or cigarettes will also serve.
-- Cats, coffee, chocolate...vices to live by Please don't feed the trolls. Killfile and ignore them so they will go away.
What frequency range ?
For low frequencies, it should look like a Faraday cage. This at least requires some electric connections between the conductive surfaces in the trousers and in the jacket.
Zippers are problematic, you may have to use some overlapping cloth and metallic snap buttons to cover the zipper. Depending on frequency, you may have to use metallic snap buttons at every 3 cm, making dressing and undressing quite painful.
How about the head/face ? Is it covered or not ?
The largest risk for RF damage is the eyes, since there are no thermal sensitive neurons in our eyes, so never look into a waveguide, which might even theoretically be powered up.
The next sensitive part is our brain due to heat damage.
What is the point of protecting the body from RF exposure, if the head is not protected ? If the head/face is not properly protected, any microwave radiation will penetrate from the opening for the neck into the lower body parts.
On a sunny day (Fri, 15 Mar 2013 16:45:57 -0700) it happened Jeff Liebermann wrote in :
Cute.
Speaking of plate armor, Boeing's "solution" to the 787 Dreamliner burning battery problem is to fortify it inside 150 lbs of steel casing. So much for the weight advantages of LiIon. I wonder if it includes a barbeque grill on top.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On a sunny day (Sat, 16 Mar 2013 09:33:16 -0700) it happened Jeff Liebermann wrote in :
I like the sentence: "Mr. Sinnett said that Boeing engineers had identified 80 different ways that the batteries could fail"
Does not make me that optimistic...
Yes the heat must go somewhere, maybe bring bacon and eggs... :-)
the batteries could fail"
That phrase is part of the standard tag line ending in "... more research is necessary". Claiming that there are XX number of unsolved problems is largely a poorly veiled solicitation for a consulting contract. I add phrases like that to most of my reports reminding the customer that if he happens to have some money left for research, I wouldn't mind getting a piece of the action.
Well, Boeing did add a "new titanium venting system" which presumably will act as a chimney or smoke stack.
The Boeing fix (800KBytes):
The technical briefing (90 min video... yawn)
The Boeing press release:
Just in case, the start of a cover up or plausible denial. What? No fire? "Venting batteries produced 'smoke' that wasn't, no fire, performed as planned." and: "a deep discharge event occurred in one cell of the planes' batteries, heating it to the point at which it vented so much hot electrolyte that an adjacent cell warmed and also vented." Domino effect for batteries by thermal transfer via electrolyte spray. Truly amazing. More research is necessary on this apparently new and previously unknown phenomenon.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Not at all. Conductive hook and loop fastenings (Velcro (Tm)) are available. Elastic conductive fabrics are available as well.
Conductive hat and veil, again with hook and loop fastenings.
Actually, protecting the feet and hands are the toughest problems.
?-)
On a sunny day (Sat, 16 Mar 2013 14:34:27 -0700) it happened Jeff Liebermann wrote in :
the batteries could fail"
I have read that pdf no, very comprehensive. A few questions pop up: Is it worth it (added weight of enclosure) cost of all that testing yet to be done, possible repeat of events, it is not enough that is is not dangerous due to fire, it is also a backup of flight systems (in flight), so it SHOULD NEVER HAPPEN, this solution looks as though they expect it to happen frequently, so why not go back to nicads, or some other technology (Airbus is working of fuel cells).
Yes, but everyday the fleet is grounded costs airlines, and I am sure they will sue Boeing, money.
Yes, industry at it best, that poor technician who warned the FAA those batteries were a flying bomb fired, wonder if they will compensate him in some way.
There is also something else, years ago when the A480 was presented (by big time politicians), I looked at he wing, and said (its on usenet) "That construction is not OK": Now they have cracks in the wing. I look at he dreamliner wing, and it sucks. It sucks from an aerodynamic POV. But just again a gut feeling. I like delta wings:
Wouldn't Space Shuttle tiles be a better solution for the Boing 787? They are very lightweight, or so I understand, and were able to keep (most of) the shuttles from burning up on re-entry.
It wasn't the silica tiles that failed on the Columbia. It was the reinforced carbon-carbon leading edge panel that crumbled when impacted by rather light weight, but high velocity, foam insulation.
I think Boeing is trying to contain an potential explosion and not just deal with the heat produced. The pure silica glass shuttle tiles are rather brittle and would probably make a nice fragmentation bomb. My guess(tm) is that the steel box is temporary and a quick fix to get the 787 back in the air, and that a more elegant solution will quietly be developed somewhat later.
Each 787 carries TWO such battery boxes. One powers the APU, which is where the two "non-fires" happened. The other box powers the cockpit instruments, which might explain the current crisis mode.
I wonder how thick the battery box will be. The modifications added
68Kg (150 lbs) to the weight of the two battery boxes, most of which is probably in the steel box. I couldn't find any dimensions on the battery box, but my guess(tm) from the photos and the Yuasa LVP-65 battery dimensions is about 40cm x 28cm x 20cm (LWH). That's a surface area of about 5,000 sq-cm. Steel has a density of 7.8 grams/cm^3. For 34Kg, that's: 34Kg * 1000gm/Kg / 7.8gm/cm^3 = 4400 cm^3 Therefore, the approximate thickness of the steel box is: 5000 cm^2 / 4400 cm^3 = 1.1 cm or .43 inches not including the weight of original box, which presumably is much lighter than 34Kg. This 7/16" thick box will probably stop a small explosion, which I guess(tm) is the justification for the weight.-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
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