Recent content by wbeaty

Remember that potential is one way of describing electric fields, and for this reason the Potential behaves something like distance. What is the potential of an object? Meaningless. It's like asking what an object's altitude is. Altitude from what, the center of the Earth? Sea level...

Note well: there are no electrons flowing through your hand. Flesh is an electrolytic conductor, not a metal. When you touch the (+) and then the (-) sequentially, there are brief flows of real, actual, genuine positive and negative ions inside your hand. No mobile electrons. They sum up...

Agreed. I disagree. Yes, in general current does not require a voltage, and voltage does not require a current. For example, persistent currents in superconductors demonstrate currents at zero voltage. And the e-field surrounding an electron? That's existence proof of a voltage at zero...

No, I'm drilling down to the cause of our disagreement. Not transistors. Not diodes. Not capacitors. Not current causing voltage.

No, e-fields don't inherently require currents. This seems to be our sticking point. In reality, any charged particle is surrounded by an e-field. A single electron is surrounded by a radial e-field. This is a fundamental element of classical EM physics. Do you disagree?

Sorry, I guess I wasn't clear enough. I think I'm close to our central disagreement. This is about clearly explaining electrical physics to the general public... and the concept that voltage causes current. But before examining silicon or even conductors, first the simplest basic situation...

Ah, so there *is* a controversy about diode explanations! OK, then before anything else we need to get clear on some very basic physics. Not voltage sweeping charges out of silicon, that's controversial stuff apparently. Not resistor operation (too controversial?) Not the nature of...

It's a diode. :) Is there really a huge controversy about how PN junctions actually work? Is there some thread on physicsforums with a long battle over explaining the diode? And pay close attention to your question above: how does a potential barrier set the rate of charges crossing [a]...

Once again again again: THIS IS FOR CHILDREN. Complexity is verboten, and complex-ifying a simple situation is not any sign of competence. "Complexifers" are extremely valuable as graduate textbook authors, as RF chip designers, and for writing the best SPICE models. But for talking to...

I just heard about a neat little schematic which keeps your transistors ice cold: Zero-volt Switching RF driver http://www.instructables.com/id/ZVS-Driver/step3/Schematics/ I'd just get rid of the flyback transformer and replace it with a big multi-turn loop antenna with a center tap...

To teach such things for 8.02 class at MIT, John Belcher developed the TEAL project: a set of mpeg field animations with a moving wood-grain effect. In this one below you can see the nearfield pattern oscillating in and out, while the farfield peels off and flies away. (It's a video loop, so...

A dipole antenna doesn't exactly "have" a single unique impedance. Yes, if we cut a half-wave conductor in two, then connect a feedline at the break, we'll find a low Z at that spot. But if we go and google up some "delta match" articles, we get our nose rubbed in the true nature of...

So, how can we explain BJTs to children? To design an explanation, first describe the basic BJT operation verbally: Base current controls the BE junction voltage BE junction voltage determines height of BE potential-barrier That potential-barrier sets the rate of charges crossing the BE...

I've devoted much thought to the topic, :) but only ever experimented using Tesla Coils lighting up fluorescent bulbs, or running low-volt solar-cell motors remotely using capacitive coupling and a diode bridge to create DC. The straightforward but hazardous experiment would be to use a...

With lightning, the direction of em energy flow is inwards towards the plasma channel. Before the lightning strike, the energy is stored in strong e-fields between clouds and earth. During the strike, the em energy flows from the e-fields towards the lightning. Note that the energy doesn't...