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phantom power Donating Member (1000+ posts) Send PM | Profile | Ignore Wed May-28-08 01:38 PM
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flux and charge
This is one of those recent memristor articles. I hadn't realized that they were proposing a new reframing of passive circuitry:

The hold-up over the last 37 years, according to professor Chua, has been a misconception that has pervaded electronic circuit theory. That misconception is that the fundamental relationship in passive circuitry is between voltage and charge. What the researchers contend is that the fundamental relationship is actually between changes-in-voltage, or flux, and charge. Such is the insight that enabled HP to invent the memristor, according to Chua and Williams.

"Electronic theorists have been using the wrong pair of variables all these years--voltage and charge. The missing part of electronic theory was that the fundamental pair of variables is flux and charge," said Chua. "The situation is analogous to what is called "Aristotle's Law of Motion, which was wrong, because he said that force must be proportional to velocity. That misled people for 2000 years until Newton came along and pointed out that Aristotle was using the wrong variables. Newton said that force is proportional to acceleration--the change in velocity. This is exactly the situation with electronic circuit theory today. All electronic textbooks have been teaching using the wrong variables--voltage and charge--explaining away inaccuracies as anomalies. What they should have been teaching is the relationship between changes in voltage, or flux, and charge."

HP invited Chua to speak about his theory a few years ago, but at that time the lab did not tell Chua that they were actively seeking the memristor. Only two weeks ago did Williams tell Chua that he had used the proper variables--flux and charge--to invent the world's first working memristor.

A memristor works by virtue of hysteresis, whereby its rate of change accelerates as it moves from one state to the other--"on" to "off," or vice versa. Hysteresis has been explained away by current circuit theory as an anomaly, according to Chua and Williams, whereas its existence is, in fact, a fundamental property of passive circuitry.

http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=207403521&printable=true

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Wilber_Stool Donating Member (1000+ posts) Send PM | Profile | Ignore Wed May-28-08 02:07 PM
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1. One of these days
someone will figure out what electricity really is, and the world will be changed forever.
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electropop Donating Member (1000+ posts) Send PM | Profile | Ignore Wed May-28-08 02:45 PM
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2. Hysteresis an anomaly?
Since when has anybody been mystified by hysteresis? It's easy to design into a circuit - just build in a bit of positive feedback. Maybe they don't train EEs like they did in my day. Why sonny, when I was a circuit-jockey no bigger'n you, I was sniffin' solder fumes just for the fun of it!
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pokerfan Donating Member (1000+ posts) Send PM | Profile | Ignore Wed May-28-08 06:07 PM
Response to Reply #2
3. Hysteresis is an anomaly in a passive device
But I don't subscribe to the theory that it constitutes a fourth passive element.
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electropop Donating Member (1000+ posts) Send PM | Profile | Ignore Thu May-29-08 08:17 AM
Response to Reply #3
4. Magnetic hysteresis and dielectric hysteresis have been around forever.
Edited on Thu May-29-08 08:17 AM by electropop
The former is how permanent magnets and magnetic recording work. The latter causes nonlinearity in capacitors and allows electret condenser mics to work. Both are just permanent molecular/crystalline realignments caused by strong fields.
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pokerfan Donating Member (1000+ posts) Send PM | Profile | Ignore Thu May-29-08 01:47 PM
Response to Reply #4
5. You were comparing to to an active device
which requires amplification. As far as magnetic and dielectric hystesis go, those can be modeled with more basic circuit elements.

The memristor is more intersting and the scientists proposing it as a fourth circuit element have indeed heard of hysteresis.

http://www.informationweek.com/news/hardware/processors/showArticle.jhtml?articleID=207403582


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