Right angle circuitry | Hacker News Reader

Right angle circuitry

amasci.com

62 pointsyread10 comments

semi-related. People who build tube guitar amps (lots of high voltage AC) take component placement very seriously. The magnetic fields floating around the chassis greatly affect tone (and noise, which is sometimes a big part of tone.)

Some of the high end amp builders I know have spent a lifetime of experimentation figuring out the best way to place components and route circuits [anecdote, no references available]

If you want a simple example, have a look inside any audio amplifier. The two transformers will always be mounted at a 90 degree angle to each other (power xformer/output xformer) to minimize noise.

Yes indeed. I have actually built a few tube guitar amps for fun. I did the designs myself and the first one produced so much noise/hum that it was practically unusable.

Twisted pair wiring, careful routing of grounds, transformer location and component selection all seem to play massive roles.

No wonder then that most amps these days are built around transistors, even though they sounds worse...

"James Clerk Maxwell might be spinning in his grave. But is he rotating around his long axis, or flipping endwise?!!!"

Only the right hand rule can tell us that.

I assume you got the link from Randall’s blog, yread? I probably should have submitted it here when I came across it a couple months ago and emailed the link around to “nerd snipe” various physicist/engineer type friends. Either way, I’m glad to see this get some discussion on Hacker News.

The author’s (William Beaty) other pages about electricity are somewhat interesting too http://amasci.com/ele-edu.html. In particular, he has some good rants about the terminology/pedagogy of E&M/electrical engineering: http://amasci.com/miscon/elect.html http://amasci.com/miscon/elteach.html http://amasci.com/miscon/whyhard1.html

In short: the terminology as used is ambiguous and confusing, and the common metaphors used to explain electricity are somewhere between misleading and wrong, and this has resulted in most people, including most textbook authors, having a poor understanding of how it actually works.

Is it bad that this is the first time a toroidal transformer has been explained to me this clearly?

Does anyone have an answer or idea for the "WHY?!!!" part of Figure 8's paragraph?

in figure 7, Faradays Law: changing magnetic field in the left torus induces a variable current in the wire, then via ampere's law the changing current in the wire induces a magnetic field in the second torus.

However in figure 8 while there is an A field which extends to infinity, don't forget that B = curl(A) and so the magnetic field of the torus is going to be confined within it. As such there's no way to induce a new field in the additional torus. A is a potential, it's not a "real" field in as much as you can only measure things like |B| and |E| (or quantum phases induced by A in the Ahranovov-Bohm experiment)

Thank you. That was a nice, concise answer! (it's been a while since I've had any E/M)

You need a current to flow in order to induce a magnetic field in the second iron ring.

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