i think there is no such things as negative resistance.

if it really exist, i think Ohm's Law or other related laws won't hold anymore..lol

This post has been edited by harrychoo: Apr 6 2006, 10:10 PM

hahaha, i think we learnt a bit too in physical electronics. I oso forgotten liao


Negative differential resistance means, the resistance value is decreasing over time mah, rite?
0 resistance is ideal, and super conductors only has very very near to zero resistance.

-ve resistance is like..... the object exist to have some energy supply (instead of resisting, it is giving energy).

This post has been edited by charge-n-go: Apr 6 2006, 11:23 PM

that is what i said, which means it impossible that a normal wire giving out energy...

I dunno how to explain to my frend that his reading is wrong....

actually im new to the job and he's senior than me, so if i go to my immediate supervisor and tell this thing, my frend my think i want to 'show power'...

LoL, i were u, i oso dunno wanna laugh or cry towards this senior

Well, if he said -ve terminal then logical la, -ve resistance is stooopig.

Ohm's Law is a very primitive law and the introduction of superconductor somehow violates it.

Negative differential resistance is something like negative temperature coefficient. The resistance of a material decreases when a controlled variable is being altered.

That is correct, but you still cant get resistance -ve...

you only decrease the resistence, but it will never reach 0, let alove -ve

In situations like these, look at the tools being used in measurement. An Ohmeter is just measuring the voltage across the resistor after pumping in a known current. If the DAC resolution is not high enough, or the voltage scaling not large enough, then the result of the measurement is bound to be erroneous. Furthermore, if the resistance of the ground wire is less than the resistance of the probe leads, then the readout is also definitely wrong.

the multimeter used is of industry standard...

while the probe is calibrated every 3 months as per requirement

Fair enough. Was it a handheld unit or a bench-top? What does the specification for the multimeter say about the resolution and accuracy? For measuring something in the milli-ohm range you should probably be using a RCL meter with Kelvin clips instead of a two-lead, contact probe multimeter.

Measuring Resistance (epanorama.net)

There is a phenomenon called negative resistance, where the current will actually increase when the voltage is reduced (and vice versa). And when that happens the circuit will actually oscillate. Quite cool stuff btw. I first learnt about it when checking out on cold fusion on J.L Naudin's website. (Note: this is not pseudoscience... )

http://jlnlabs.imars.com/cnr/index.htm
http://en.wikipedia.org/wiki/Negative_Resistance

Actually it's possible to get a -ve reading.

1)ground bounce (the ground voltage jumped to a positive voltage when you place the probe, should be very transient though). Since we always "assume" that ground = 0v, that can explain some things...
2)there is a voltage source connected. (will probably screw up your multimeter permanently though)

This post has been edited by martianunlimited: Apr 8 2006, 03:05 PM

I don't know how I managed to miss this thread all this months, heheh... anyways, int19h checking in. Atm my interests are mainly with top-level architectural design, eg mapping algorithms to array structures, augmenting existing processor core designs with custom instructions... simple noob stuff like that. I'd rather stay away from the low-level stuff, will leave that to you guys

[edit: clarified something]

This post has been edited by int19h: Apr 17 2006, 03:40 PM

hola, im new hear.
taking computer engineering in mmu.

just would like to join this thread even though im just in second year.
seems like u guy's topic are too advance for me

neway, lets bring this up, up n away.

W00t i have LVSed already! A bit more tweaking and i'm done!

MAD MAC 525 layout:
http://www.contrib.andrew.cmu.edu/~fma/cmu...t%20labeled.PNG

Win, gold and binary!

Yes, finally done with my 8-bit CPU FYP. It is working !!

neat mask layout
i really need to brush up my skill to your level
= /

I didn't layout the whole chip, i did the adder and part of the multiplier only. 13000 transistors is a bit much for one person (with other work) to layout in a month and a half

The key is good floorplanning and size estimation. My team's initial predictions on size and transistor counts were very detailed and almost spot on, which helped a lot. We also floorplanned the chip early on and enforced area and shape restrictions for the modules once the initial layout started and everyone stuck to it so we got the shape nice with few gaps and a good transistor density.

Of course above all you need a good team to work with and my team did a good job, i didn't have to fix that much stuff

This post has been edited by ikanayam: Apr 21 2006, 01:33 AM

reporting in !

Boss charge-n-go ...

hahaha :Þ

Do you guys have any recommended website about applications of signal flow graph?

going to grad liao only u report ar...


What about google?
i think SFG is useful for defining the input/output of a system.

Anyone knows where in penang can i get PCB developing service?? UV,Develope and Etching need it to do a circuit for my FYP

This post has been edited by Cloudx: Apr 27 2006, 12:59 PM