what component is this?

[Cyparagon]

Isn't negative resistance impossible to make?

Nope. My understanding: The more current you send through an ionized gas, the more ions it creates, and therefore the lower the resistance, and therefore the lower the voltage drop, and therefore the higher the current ad infinitum.

 

[chipdouglas]

just a little update if any of you care.... i replaced the resistor but the burnt part of the board was burnt so badly i couldn't trace where the paths went.


michael

 

[Eudaimonium]

just a little update if any of you care.... i replaced the resistor but the burnt part of the board was burnt so badly i couldn't trace where the paths went.


michael

If it's only a layer of soot, it's easily cleaned with a solvent to see traces.

What exactly do you mean, burned?

 

[chipdouglas]

the actual pc board was burned too. and charred all the way through.

 

[HIMNL9]

Then now it's conductive ..... scratch away all the burned (carbonized) part, or the circuit can go shortcircuited from this, especially for main power sections.

Better some unhestetical holes in the PCB and paths re-made with wire and solder, than a new "KABOOM" when you turn it on again

 

[Eudaimonium]

Then now it's conductive ..... scratch away all the burned (carbonized) part, or the circuit can go shortcircuited from this, especially for main power sections.

Better some unhestetical holes in the PCB and paths re-made with wire and solder, than a new "KABOOM" when you turn it on again

Exactly, however you look at it, it needs to be taken care of, otherwise ...

Here's the first thing coming to mind when somebody says "Burned PCB":

Oh and, about the "KABOOM" part, it's a shame that stuff rarely actually explodes due to short circuit somewhere, they just most likely flip the main fuse switch in your house shutting your lights down, and then stinking up your room

They don't even have the decency to go out in style!

 

[HIMNL9]

Right this, i meant ..... when the PCB is burned like that one, you will need to take away all the carbonized part, and then redo the paths with solid wires and solder ..... cause the carbonized part is not more insulating, it becomed conductive (not like a piece of wire, but enough for cause a lot of problems)

They don't even have the decency to go out in style!

ROTFL , really

 

[csshih]

yeah. they're more of a plbbbbbtt *sizzle* *fuzzz* *feeeeep(smell)*

 

[LSRFAQ]

Electrofreaky forgot the tolerances GOLD SILVER NONE = GET SOME NOW! = 5-10-20%

Not exactly PC is it...

Steve

 

[kristopher]

A friend of mine always says once you let the smoke out, they're no good anymore!

As to negative resistances, you can get that with quantum well states. As you line up a well the device starts to conduct, but as the state becomes too high, then it stops conducting until the next well lines up. Essentially the IV curve has bumps in it, and with negative slope that means negative resistivity. There is a (quite highly technical) explanation here, but you can look at figure 4 to see a graph of what I was trying to explain:

Influence of Transit-Time and Quantum Well Negative Resistances on Quantum Well Oscillators

 

[HIMNL9]

"Negative" resistance (sorta of, anyway, it's negative "differential" resistance ), already exists from long time, in electronic components ..... never heard about tunnel diodes ?

 

[Eudaimonium]

I know what tunnel diodes are and I know about all this stuff you are saying. Problem is this is not a negative resistance as we figure it, as far as I can tell it's something closely resembling negative resistance, under very strict circuimstances.

Actual negative resistance would be if you simply took your DMM, and measure -5 ohms across a component (at any given time/temp).

If normal resistance dissipates electrical power into thermal power, then negative resistance would in some way gather the sorrounding energy from the component and feed it to the existing electrical circuit (that's the way I figure, at least).
So basically, working component would need heating, not cooling, to keep working since it'll get colder and colder (drawing heat from itself and sorrounding air/whateva).

Now, you can almost make something like it, for example having an amplifier (transistor technology rulez, eh?). The amplification is essentially making small power signal into large power signal. Problem is, it's drawing a secondary power source to add to the signal being amplified. If one is to have anything else but electricity being converted into more electricity (adding to the existing one in the circuit), THEN you'd have negative electrical resistance in ideal form.

Tunnel diodes don't do that when they are in the so called negative resistance state in their graphs, correct? They just behave abnormally for electrical components, but not actually feeding more current into the existing circuit via supernatural means.

Somebody correct me if I'm wrong, I so seriously want to be wrong in the opinion that negative resistance as I've imagined does not exist.

 

[HIMNL9]

No, Eudaimonium, you're basically right, a true "negative resistance" must be a component that GIVE you energy when you use it, instead TAKE energy ..... just for make a (paradoxal, but true ) example, a negative resistor can be a resistor that, instead eat energy and dissipate it in heat when is powered, take heat from the ambient and give you more energy of the one that you use for power it ..... but we're too much used to reason in standard ways, for imagine something similar in the reality .....

I mean, you know basical ohm law, 1V across an 1 ohm resistor give you a current of 1A and dissipate 1W/s in heat ..... now try to imagine a concrete device that, with 1V across 1 ohm (and no other power supplies), TAKE 1W/s of heat from the ambient and give you 2A of current in result ..... a bit difficult, isn't ?

 

[Eudaimonium]

HIMNL9 - That's my whole point! There is no such a device at all (at least not yet), hence I draw a conclusion that a negative resistance is impossible to achieve (at least with known technology so far).

Cyparagon has said that I'm wrong and provided link to Wikipedia, but that's not a true answer to the question at hand, is it?

On the other hand, there's this thing constanty begging to get noticed, the Thermo Electric Cooling elements...

There's Seedback effect and it's reverse counter part, Peltier's effect ... well, we know that a thermocouple metals give off heat from one side and take it from the other...

But what is the exact physical explanation for atoms there deciding that they'll stand still if the current passes, rubbing it in the face of all other atoms who jump crazy from electrons flowing through?

Do you think it would be possible to get only the cold side of TEC bloc?
We already have a hot-only side, heaters/resistors. Sounds perfectly reasonable that at some point, some dude will figure out a counter part to resistor, a cold-only side element of TEC.

 

[HIMNL9]

No, is not possible to get only one side of a Peltier cell, cause it's a bipolar device, and it does not work without a difference of temperature ..... anyway, the Seebeck effect is not a true negative resistance, cause it still gives much less of the energy (in current) of that what you pump in it (in heat).

At the moment, is matter of science fiction only, same as the "second degree perpetual motus"

 

[ElektroFreak]

Yeah, your digital electronics prof could have been a little more appropriately creative. There is no place for that. Sorry but I'm a real beast where it comes down to that stuff!:tsk:

LOL... ok then. Why don't you go on ahead and tell all the THOUSANDS of electronics engineers and professors out there that have been passing that around for YEARS that they're "being bad". LOL!!!

Seriously, ya might want to find something better to whine about. Maybe (I know it's a real stretch) just maybe you could even stay on the topic of lasers and electronics instead of trying to "police" something that has been around for decades.