You've just added in a simulation of an infinitely long lasting power supply.
Making a real negative resistor along those lines would involve having a real infinitely long lasting power supply. Last time I checked, they were hard to come by.
Sylvia.
a question about resistors in an arc experiment
Jan 15, 2009
381 Replies
Positively excellent retort.
And to think that you fat, retarded bastards have been calling me a troll.
I would say zero current flow. As in open circuit.
Certainly the current tends towards zero as the resistance tends towards infinity (or minus infinity).
But for a resistance that is "greater than infinite"? Not possible to say without a definition of the term.
Sylvia.
Have you managed to run my simulation yet?
JF
slope
You\'re looking at the wrong thing.
Look at the voltage into R4 and the current through it.
With a rail-to-rail input and output opamp it\'s much nicer:
Version 4
SHEET 1 880 680
WIRE 384 -16 -96 -16
WIRE 176 48 128 48
WIRE 320 48 256 48
WIRE 192 96 -32 96
WIRE -96 128 -96 -16
WIRE 192 128 192 96
WIRE -32 144 -32 96
WIRE -32 144 -288 144
WIRE 0 144 -32 144
WIRE 128 144 128 48
WIRE 128 144 80 144
WIRE 160 144 128 144
WIRE 320 160 320 48
WIRE 320 160 224 160
WIRE 160 176 128 176
WIRE 192 208 192 192
WIRE 192 208 16 208
WIRE -288 240 -288 144
WIRE 128 256 128 176
WIRE 176 256 128 256
WIRE 320 256 320 160
WIRE 320 256 256 256
WIRE 128 304 128 256
WIRE -96 400 -96 160
WIRE -288 416 -288 320
WIRE 16 416 16 208
WIRE 16 416 -288 416
WIRE 128 416 128 384
WIRE 128 416 16 416
WIRE 128 464 128 416
WIRE -96 512 -96 432
WIRE 384 512 384 -16
WIRE 384 512 -96 512
FLAG 128 464 0
SYMBOL res 112 288 R0
SYMATTR InstName R1
SYMATTR Value 100k
SYMBOL res 272 240 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 100k
SYMBOL res 272 32 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R3
SYMATTR Value 490
SYMBOL voltage -288 224 R0
WINDOW 3 24 104 Invisible 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR Value PULSE(12 0 0 0 .1)
SYMATTR InstName V3
SYMBOL res 96 128 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R4
SYMATTR Value 490
SYMBOL Opamps\\\\LT1797 192 96 R0
SYMATTR InstName U1
TEXT -8 440 Left 0 !.tran .02 uic
TEXT -112 416 Left 0 ;> >
TEXT -112 144 Left 0 ;> >
JF
I haven't tried. I don't see what point you think you're making.
Sylvia.
No, I\'ve just made the input signal the opamp\'s power supply as well,
obviating the need for an infinitely long lasting power supply.
After all, if there\'s no signal present of what use is the supply?
You\'ll never know if you don\'t try...
Anyway, What\'s the matter; afraid you might learn something and feel
indebted?
JF
Not as much fun, though ;-)
-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)
You should adopt that as a sig, John.
-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)
It's a bad photo to judge from, but Sylvia looks emaciated... that's pushing "skinny" just a wee bit too far ;-)
...Jim Thompson
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
Obstinate? See the SIG, you're blundering along riding a collection of bad assumptions.
It's alright, around here, to admit error. Actually, it's admirable, it happens so rarely ;-)
...Jim Thompson
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
It\'s what you learn, after you know it all, that counts.
slope
I still don't get it. If I run the transient response, just as you set it up, the opamp output is stuck near ground and the V3 source sees a load of about 1K to near ground, plus the opamp supply current. The opamp is just an expensive ground.
So what's the function of the circuit?
John
I've run your sim, comments posted elsewhere, and I can't figure out what the circuit is supposed to do.
John
he
is
ede
nNo, it follows Ohm's law with a minus resistance value:
V =3D R * I
The value of R is negative.
lYou seem not to understand that there are two types of negative resistors. Both are validly negative. Try thinking about the conductance of a negative resistor. Consider passing resistance through zero and then consider passing conductance through zero. You will see that they don't both take you to the same place.
There's cause to think that neither you nor I are gorgeous burning hunks of male beauty.
John
I did a walk through the Cornell EE department. Just for fun, I counted oscilloscope screens (three) and PC screens (had to be a hundred, maybe.)
My office is a little better, three oscilloscopes (as many as Cornell!) and two PCs. I actually own about 40 scopes and 5 PCs.
John
Hardly ;-)
But does your "skinny" preference descend to "bony" ?:-)
...Jim Thompson
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
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