Slashdot Mirror

Bah. I entered the link and Slashdot removed it.

http://techlib.com/files/RFDes...

See http://www.techlib.com/area_50/xraydefender.htm -- tho techlib.com isn't resolving right now (server down, I'll bet), so you'll just have to try an alternate source:

http://www.techlib.com.nyud.net:8090/area_50/xraydefender.htm coral cache says gateway timed out...
http://wayback.archive.org/web/*/www.techlib.com/area_50/xraydefender.htm wayback machine doesn't have it archived...
http://webcache.googleusercontent.com/search?q=cache:SErH8Fhj52cJ:www.techlib.com/area_50/xraydefender.htm+site:techlib.com+backscatter&cd=1&hl=en&ct=clnk&gl=us&ie=UTF-8&source=www.google.com -- you can at least read the text on google, and get thumbnails of the images on the page:
http://www.google.com/search?oe=UTF-8&q=site:techlib.com+backscatter&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&hl=en&tab=wi
Too bad the schematic isn't readable at thumbnail-size, but maybe techlib.com will be back up soon?

As far as radio interference goes, Wenzel's Techlib has some info about how to mitigate this. Of course, sdddddddddddwsssssssssssssss cvvvvvvvvvvvvvv;;;;;;;;;;;;;;
Sorry, cat got on keyboard. Anyway. Of course, it's not like the technicians installing the meters are checking for ground loops... but perhaps they should be? If there is that much potential to interfere with first responders, you'd think some tests on the wiring would be in order...

I'm not sure about the wireless hacking from a laptop mentioned in TFS, but, as far as RF transmissions, these things can generate plenty of spread-spectrum modulation EMF when modulating the 240kHz signal carrier on wire.
There's a good discussion about eliminating ground loops so as to avoid broadcasting the signal as a source of interference at the Technical Library; I suppose one could always use an induction receiver to go the other direction, using a loop antenna. Obviously, modification of the above designs is needed for target frequency band. AM radio circuits might be a good place to start, too.
Actually, there are tons of good MW box loop designs that already go well below 240kHz; that page includes a calculator, and playing with some quick numbers suggests a 48cmX65cm frame [=56.5cm side length] for a 16-turn coil extending 21cm in length in parallel with four 470pF caps gives us resonance at 245kHz. Of course, with 20% tolerance ceramic discs, you may want to replace one of the 470's with a 4-40pF variable cap in parallel with anywhere from a 150pF to a 39pF paralleled with a 560pF, depending on how low or high the 470's are measuring.

[Disclaimer: I am an RF amateur.]

I'm not sure about the wireless hacking from a laptop mentioned in TFS, but, as far as RF transmissions, these things can generate plenty of spread-spectrum modulation EMF when modulating the 240kHz signal carrier on wire.
There's a good discussion about eliminating ground loops so as to avoid broadcasting the signal as a source of interference at the Technical Library; I suppose one could always use an induction receiver to go the other direction, using a loop antenna. Obviously, modification of the above designs is needed for target frequency band. AM radio circuits might be a good place to start, too.
Actually, there are tons of good MW box loop designs that already go well below 240kHz; that page includes a calculator, and playing with some quick numbers suggests a 48cmX65cm frame [=56.5cm side length] for a 16-turn coil extending 21cm in length in parallel with four 470pF caps gives us resonance at 245kHz. Of course, with 20% tolerance ceramic discs, you may want to replace one of the 470's with a 4-40pF variable cap in parallel with anywhere from a 150pF to a 39pF paralleled with a 560pF, depending on how low or high the 470's are measuring.

[Disclaimer: I am an RF amateur.]

I'm not sure about the wireless hacking from a laptop mentioned in TFS, but, as far as RF transmissions, these things can generate plenty of spread-spectrum modulation EMF when modulating the 240kHz signal carrier on wire.
There's a good discussion about eliminating ground loops so as to avoid broadcasting the signal as a source of interference at the Technical Library; I suppose one could always use an induction receiver to go the other direction, using a loop antenna. Obviously, modification of the above designs is needed for target frequency band. AM radio circuits might be a good place to start, too.
Actually, there are tons of good MW box loop designs that already go well below 240kHz; that page includes a calculator, and playing with some quick numbers suggests a 48cmX65cm frame [=56.5cm side length] for a 16-turn coil extending 21cm in length in parallel with four 470pF caps gives us resonance at 245kHz. Of course, with 20% tolerance ceramic discs, you may want to replace one of the 470's with a 4-40pF variable cap in parallel with anywhere from a 150pF to a 39pF paralleled with a 560pF, depending on how low or high the 470's are measuring.

[Disclaimer: I am an RF amateur.]

I'm not sure about the wireless hacking from a laptop mentioned in TFS, but, as far as RF transmissions, these things can generate plenty of spread-spectrum modulation EMF when modulating the 240kHz signal carrier on wire.
There's a good discussion about eliminating ground loops so as to avoid broadcasting the signal as a source of interference at the Technical Library; I suppose one could always use an induction receiver to go the other direction, using a loop antenna. Obviously, modification of the above designs is needed for target frequency band. AM radio circuits might be a good place to start, too.
Actually, there are tons of good MW box loop designs that already go well below 240kHz; that page includes a calculator, and playing with some quick numbers suggests a 48cmX65cm frame [=56.5cm side length] for a 16-turn coil extending 21cm in length in parallel with four 470pF caps gives us resonance at 245kHz. Of course, with 20% tolerance ceramic discs, you may want to replace one of the 470's with a 4-40pF variable cap in parallel with anywhere from a 150pF to a 39pF paralleled with a 560pF, depending on how low or high the 470's are measuring.

[Disclaimer: I am an RF amateur.]

If they become illegal, build your own!

Fortunately, all it takes to make an ion-detector chamber is a tin can, some wire, and an NPN transistor!

http://www.techlib.com/science/ion.html

Happy ion counting!

Linky link.

You apparently aren't an EE. There are a number of ways to do voltage multiplication without a (large) transformer (technically, you can do it without the XMFR, it just helps).

Here is one way. I'm too lazy to try to find a better link with some theory attached, but if you follow the current path on the voltage swings, you should be able to figure it out.