4 ms·

Right angle circuitry

62 points by yread 16y ago

networkjester 16y ago
Does anyone have an answer or idea for the "WHY?!!!" part of Figure 8's paragraph?
- jackdawjack 16y ago
  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)
  - networkjester 16y ago
    Thank you. That was a nice, concise answer! (it's been a while since I've had any E/M)
- tome 16y ago
  You need a current to flow in order to induce a magnetic field in the second iron ring.
tricky 16y ago
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.
- aarongough 16y ago
  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...
mmagin 16y ago
"James Clerk Maxwell might be spinning in his grave. But is he rotating around his long axis, or flipping endwise?!!!"
- rikthevik 16y ago
  Only the right hand rule can tell us that.
pixelbath 16y ago
Is it bad that this is the first time a toroidal transformer has been explained to me this clearly?
jacobolus 16y ago
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 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/elect.html http://amasci.com/miscon/elteach.html http://amasci.com/miscon/elteach.html http://amasci.com/miscon/whyhard1.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.

62 points by yread 16y ago

networkjester 16y ago

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

jackdawjack 16y ago
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)
- networkjester 16y ago
  Thank you. That was a nice, concise answer! (it's been a while since I've had any E/M)
tome 16y ago
You need a current to flow in order to induce a magnetic field in the second iron ring.

tricky 16y ago

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.

aarongough 16y ago
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...

mmagin 16y ago

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

rikthevik 16y ago
Only the right hand rule can tell us that.

pixelbath 16y ago

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

jacobolus 16y ago

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 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/elect.html http://amasci.com/miscon/elteach.html http://amasci.com/miscon/elteach.html http://amasci.com/miscon/whyhard1.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.