Electronic US Currency

[DStewart]

Back in 1993 (or there abouts) there was an article in Nuts & Volts about the ability to determine the amount of cash some one had on their person. Related to metal threads in the bills. Does any one know about this or has a copy of the article?

[russlk]

Interesting theory, but I put a dollar bill in the microwave to see what would happen: nothing, therefore no metal threads.

[bodgy]

Try it with a £20 note. All UK notes have a metal security strip in them .

[DonFromCT]

<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by Russ Kincaid:
Interesting theory, but I put a dollar bill in the microwave to see what would happen: nothing, therefore no metal threads.<hr></blockquote><p>I don't think they have this in the dollar yet. Try it with a twenty. I'm not sure if is metal, but the strip can be seen vertically on the left side of the bill if you hold it up to a light.

[Chris Smith]

It is a metallic strip, and it may not react to "turkey oven frequency" but two or more strips will react at one or more of the many Microwave frequencies. Two strips placed adjacent will form a capacitor with the muslin paper/cloth forming the dielectric. By random chance alone you need a minimal of three or more bills to form a capacitor. The more bills your have the greater the field strength and you can measure this field of re-radiation. To what accuracy would depend on the sensitively of your receiving equipment, and possibly distance from the object. How to count them, I don't know but experimenting would give a number that you would have to cross reference by experimenting. The basic principal is simple with saturation and re-emission. A friend at Litton about 15 years back had access to the variable RF generators to do this experiment but I don't have those actual microwave frequencies my self. Microwave frequency however covers from the low Infra red of around 800 nm, and technically goes well into the Tera hertz. This makes a couple of billion frequencies possible? Government equipment these days are so sensitive that picking up the RF generated on almost any circuit board including cameras that are recording but not broadcasting, is a simple task. They can even receive cable transmissions of video cameras with out physically tapping the lines. Perhaps their equipment isn't targeted at counting the money but rather counting if there is a "large" quantity and perhaps that's enough for them? This may give them PC, or just to hassle you, follow you, or what ever? The principle is one of the most basic principals in electronics and if you want to defeat it, you will need to wrap your money deep inside metal foil wrapping of several layers, or a light tight metal box.