Originally posted by Andrew Hamilton
Thanks for that 🙂

I was rather hoping that it wasn’t true that a material cannot superconduct when you have an AC current because that would be a bit of a pity if it was true I think.

He should have said a semiconductor diode or transistor that happens to be a superconductor cannot conduct in both directions, that is the nature of diodes and transistors.

That's why you have to have two types of transistors, a P type and an N type usually, in a circuit to amplify a complete sine wave or audio or video analog signal. Digital signals are only one way conductive by their very nature.

1 can be represented by a positive pulse and a 0 can be represented by the opposite, usually something close to zero. It could be the other way round, a 1 being close to ground, zero volts and a 0 being a plus voltage.

It can also be the negative voltage equivalent, a 0 being zero volts or slightly negative and a 1 somewhat more negative, say 0 = 0 volts and 1 = -5 volts. Either way there is only a one way conduction of current.

Analog signals have to be amplified in both directions which is why you need two transistors usually. There are amplifiers that only need one transistor but that is called Class A, which conducts all the time and is not very efficient energy wise.

The two transistor version is called Class B, where one transistor conducts on the positive side of the wave and the other conducts on the negative side of the wave.
That type can be pretty energy efficient, there are other types more efficient, class D which I won't go into here but class B is the normal method of analog amplification.

Here is a bit on class B amps, if you look at the circuit, there are transistors marked TIP41 and TIP42, if you look close you see little arrows on the lines inside the circle of the transistor. One has the arrow pointing away from the vertical line and the other arrow is pointing to the vertical line, that shows one being NPN (TIP41) and the TIP42 is PNP. (P type)

http://www.allaboutcircuits.com/vol_6/chpt_6/10.html

The triangles before those parts are called Op-amps, neat little buggers that nowadays are very low noise and very fast amps for small signals. They are two triangles but one part, TL082, 1/2 of one in each triangle. But that's another story🙂

Originally posted by dannyUchiha
No offense to anybody, but that article seems like a load of crap. I have studied superconductivity for the last 2 years, and I'm still waiting for a serious, scientific paper that mentions this discovery.

Also, the person that discovers superconductivity above 200K is sure to win a Nobel prize almost inmediately.

Superconductivity is a field tha ...[text shortened]... engineers working around the clock, but we are still nowhere near a Tc of 200K, let alone 254K!

I already said as much. The fact he mentions a 'high tech DVM' says to me he is using maybe an 8 digit lab meter and seeing no voltage, assumes it has to be superconductivity, which needs a lot more sophisticated equipment than DVM's to prove. To ascribe superconductivity to a layer in a semiconductor does not allow for sustained current loops for instance since that requires a loop of SC wire and a means to induce a current flow and a means to measure that current, usually magnetically, not with some 'high tech DVM' so it's no wonder the scientific community has shunned this dude.

Here is one question for you since you have studied SC for years, can an alternating current be induced into a SC closed loop? My guess is not, it would radiate away energy as EM.

Also, can you induce a single electron to fly around an SC loop? If so could you measure it? Would the measurement of a single electron upset the flow of that electron through the SC matrix?