a question about resistors in an arc experiment

The circuit was both original and correct. It debounces a switch and obviously produces a clean positive glitch, with a minumum of parts. If somebody wants a negative glitch, it's trivial to modify. The circuit was a gift, not a challenge, and was accompanied by no personal comments of any sort.

Quit whining and post some circuits that are either original or correct. And if you do include insults and challenges, I'd suggest you make some small effort to be right, or even the skinny girls in the group will cheerfully whack you.

How's that?

John

Well, excuse the bloody hell out of me.

Thanks, Rich

Maybe *you* were, but everyone else had a clue.

select it with the move tool and hit ctrl-R twice stick it back where you found it.

yeah it'd be nice to be able to do that with the current probe tool. Actually it'd be nice to be able to reverse the polarity anywhere the current probe can be used. (eg -ve supply of the op-amp)

The two of you need to settle on some terminology.

There's the resistance defined by V/I, the large signal, operating point, or whatever you want to call it 'resistance'. Then, there's the small signal, differential, or region, defined by dV/dI.

Sylvia is referring to the former, you, the latter. Each definition has different implications for stability, power dissipation and other properties of a circuit.

The terminology is quite settled.

The former being negative makes no sense in the real world, so is ignored. The latter is known as "negative resistance". The derivative is understood by everyone with the exception of Sylvia, and perhaps yourself. This has been made clear many times in this thread but she refuses to listen.

Sylvia's reference doesn't exist.

...Jim Thompson

What an astounding concept. Maybe you could make that your sig file. Or your company motto.

John

You're just not used to guys who aren't hostile to women.

It is interesting to see you and JT play the little-boys-club game and try to chase women off. It's not the first time this has happened here. I'm siding with Sylvia because she stood her ground sensibly in pointing out that you were wrong, and because she totally shut down JTs ability to make an objective comment on a simple circuit... because he can't apparently stand to have a "girl" be right.

So yeah, as far as that goes, Sylvia rocks.

John

--- Here's the statement in its proper context, cheater:

"It doesn't make any difference whether it worked or not, the point was that an active negative resistance using its input signal as a supply would be the equivalent of a passive one."

Another use of it, in proper context, might be:

"It doesn't make any difference whether it worked or not, Larkin claimed, regarding his 555 trigger circuit, that: "The circuit was both original and correct.""

JF JF

Well, that's wrong too.

The polarity was flipped for some pin on a 555. The principle remains useful. The intent was to help. It does make a nice debounced pulse.

You are getting to be the village busybody, all dispute and clucking. In some threads, your posts are nothing but insults, to various people, with zero content. Do some electronics; you'll feel better.

John

I think John knows very well that we're talking about the former.

Sylvia.

You haven't been paying much attention then. This subthread has included discussion of a number of circuits that were intended to behave in the way a negative resistor (that is, one presenting total negative resistance) would behave. The debate (for want of a better word) has then centred on whether those circuits work as claimed, and the extent to which they can justifiably qualify as negative resistors given their various limitations.

But, hey, if you just want to insult me, and it makes you feel better, then go ahead.

Sylvia.

Which they always are, given that there is some capcitance between the leads. I visualise the voltage increasing until it reaches the breakdown insulation of either the resistor, or the air. In the latter case, we'd get an arc, which is where this thread came in.

Sylvia.

Both of the posted opamp-based neg-R simulation circuits are unstable if connected to a cap. The second one makes a nice exponentially-increasing voltage, V = e^(-T/RC), where R is negative, until the amp rails.

The first one certainly freaks out the opamp by ac-grounding its inverting input, doing I'm not exactly sure what. It would be stable for some small cap values.

John

I was paying attention to you denying that negative resistance was possible (indeed common), while refusing to acknowledge that you were the one using incorrect terminology.

Nope. I have no animosity toward you. Just don't be so pig headed.