a question about resistors in an arc experiment

Clearly a 2-terminal negative resistor with no internal power source, which his circuit claims to be, violates conservation of energy.

Conservation of Energy is one of the few laws I'm not willing to mess with.

You can make an unpowered 2-terminal circuit with a region of incremental negative resistance, but his circuit doesn't do that, either.

John

So what _is_ your dispute? Hot and bothered that a negative resistance region obtained using an active circuit (in a way a form of gyrator) does not fit your definition of a negative resistor?

...Jim Thompson

Jim, have you run JFs circuit? Do you think it behaves like a negative resistor?

Here. I'll do it for you. I loaded it exactly as he posted it, and ran the transient sweep as he set it up. I changed nothing.

ftp://jjlarkin.lmi.net/JF.jpg

The nodes plotted are the V3 supply, the R3-R4 junction, and the low end of R3, the opamp output.

Well, who is right, JF or Sylvia? Boy or girl?

John

OK, now meet some of the COBOL programmers who are handling all your money.

John

Change that "emaciated" to "dried up" ;-)

...Jim Thompson

On Sun, 18 Jan 2009 11:08:04 -0800, John Larkin

This is a very neat scope. We have one at work. It has a couple of deficiencies, though. I wish it had more than 2500 capture points.

And, you can't look at all captured data previous to the trigger point (with the sweep stopped) if you expand the sweep speed too much.

And, finally, on the Tek forum there is a description of a measurement problem:

More like the atonality of Berg, Dvorak, Schoenberg, Webern, Bartok and Stravinsky, all scrambled together ;-)

...Jim Thompson

Heck, I have a huge gap, 24 kilobytes, between my last HELP message text and the start of the Xilinx config stuff. It only assembles to about 40 kilobytes so far.

A 68332 can do .W (16 bit addressing) on the bottom 32K of code space, and sign extends that to include the top 32K of the 32-bit space, which is i/o and CPU ram. I use .L addressing above 32K, 0x00008000 and up, which is just lookup tables and help text and Xilinx config stuff and some chunks of flash. Easy.

John

There's no accounting for taste. You like AlwaysWrong too, don't you?

John

So what? The current through R4 is not the current being input into the circuit, because some goes into the V+ pin of the Op-amp.

Sylvia.

Crimnany, he was trying to help you out. You were the one that was unfamiliar with simulation software, remember?

The issues are already stated in the text you've quoted above.

Sylvia.

Like anybody here gives a fat flying f*ck who you decide to 'write off'.

No, he does not particularly like me.

JF has pretty much sat idly by for the last couple years in the groups. Maybe a hundred posts, if we do not count all these reply posts once you get him going when you won't admit an error.

He is probably the calmest guy in here. He strikes me as a well read, well spoken old stoner engineer that probably has more on the ball than most folks in here do. Certainly more than your reactionary ass does. You seem to like jumping on bandwagons. Right now it is the krw name calling bullshit bandwagon... you even came up with your own names. I do not think you even know what an open mind is, and that is what has your mind throttled.

And that is dubious ;-)

...Jim Thompson

He's just reading the sign of the R4 current backwards. It starts at

The opamp is railed low, and does nothing.

ftp://jjlarkin.lmi.net/JF.jpg

Look, for example, when V3=10 volts. The R4-R3 junction is at 5 volts. The opamp output is as close to ground as doesn't matter. Current is flowing INTO R4.

John

Analyze JFs "negative resistance" circuit for us.

John

Muzak is uniformly irritating and banal, Phil is frequently amusing and never banal.

Best regards, Spehro Pefhany