a question about resistors in an arc experiment

I think the problem with that one is the current-voltage line does not go through the origin. (In fact the simulation is still unphysical for me, with current at -8mA at 0V supply!)

For me, the essential quality of a "resistor" would be that it should closely follow Ohms law. That is, I = V/R where R is a constant (or close to it).

I have the movie on DVD...

...Jim Thompson

You sound like a leftie weenie, telling me what *I* can believe, DimBulb.

When we (engineers who design electronics) draw opamps, we don't always show the power supplies, because we all know that opamps need power supplies to work. And we don't always insert every adjective and every qualifier into a sentence where we know other circuit designers will perfectly understand our intent. And most of us take conservation of energy for granted.

In other words, don't be a PITA.

Good grief.

John

That's the circuit I used, in a box with two 9-volt batteries, in my class project ca 1968. I used a 709 opamp, as I recall. It was fun, plugging negative numbers into all the classic circuit equations and seeing the actual waveforms.

Sylvia should try it.

John

It works fine in LT Spice. A -10 ohm resistor connected to a 1 volt battery charges the battery at 0.1 amps.

Perhaps you meant "simulate in hardware." If that's what you meant, you should have said so.

John

There's (at least) one nice direct application of this idea - compensating for the winding resistance in a DC motor speed controller.

I think it's accurate to call the hardware circuit an *emulation* of a negative resistor. Which can of course be simulated :) But the hardware implementation is - or has - a real, physical, resistance.

You can do that in power supplies, too, to make up for wire resistance to a remote load. A lot of hysteretic buck switchers have inherent negative output resistance, for reasons I don't know.

John

I withdraw my "smart girl" comments.

...Jim Thompson

slope

Well, the point is to have fun with whatever anybody posts, isn't it?

John

Yeah, I just said it was nice to have a girlie around. :)

Maybe she's cute.

On a related note, I was just contemplating the wisdom of the 19th ammendment, when I remembered that it was immediately preceded by 3 foolish and regrettable ammendments which men alone voted for.

This is SOP in brush DC motor drives. It is called "IR Compensation" in the industry.

Kilovolts? Where do the kilovolts come from, and when?

John

If you actually know anything about the electrical properties of arcs, say so. Seems what you mostly do is juvenile he-said-she-said crap.

John

power.

He should have listened to them. He might not have died of a morphine OD.

John

power.

See the movie. He was a very stressed-out individual.

...Jim Thompson