[Lifewater]

Originally Posted by anToNIcHeN

"Oh Lord what to do???.... I asked a simple question and look at what I got!"...
hahahaha.... I am just thinking what this poor soul is going thru right now!..

Yeah Dear got a lot of gyan but now with all these maths it seems I will have to go back and try all connecting options and give it a listen and then stick to the connection in which it plays best.

[navin]

Originally Posted by Lifewater

Yeah Dear got a lot of gyan but now with all these maths it seems I will have to go back and try all connecting options and give it a listen and then stick to the connection in which it plays best.

Lifewater, Ignore the "mumbo-jumbo". Just try what I said in post #4.

[panky12345]

hahahaha..... this thread looks like my XI th std physics text book!!!!

[DerAlte]

Originally Posted by santosh.s

Well, I was trying to avoid differential equations as promised. I assumed "v" to be constant in the "illustration". ... No..no... this is completely wrong. Before drawing any conclusion about how R affects the equation, you must be sure that I is independent of it, when rest of the system doesn't change. But in this case, I is dependent on R, EMF is not. So, you should use the equation EMF^2 / R instead of above. You are saying open circuit will dissipate maximum heat whereas a short will not dissipate anything at all? That would have been true for a given current, but it is exactly opposite for a give voltae!!

Santosh-bhau, hush, you'll manage to wake up M/s Lenz, Faraday, Maxwell, and in all probability Mr. Ohm too. Perhaps if you revisit their sayings things will be simpler.

As an applied science pursuit, engineering does make assumptions, most of them implicit - but the scene is not that bad that we have to discretize the parameters involved and make independent (and most likely incorrect) assumptions of 2nd and 3rd orders, especially with others' thinking. We are just trying to run having tied our shoelaces, so to say! Things start to disprove themselves the more the parameters are dissected. Like Heisenberg Uncertainty principle can be used to prove electricity cannot flow.

"For a current induced in a conductor, the current flows in such a direction that its own magnetic field opposes the change that produced it". Implicit:
1. The circuit is closed
2. There is work done to produce the current (the moving force part)
3. There is work done by "induced" system to oppose the mag field that produced it in the first place (the induced EMF part)
4. EMF, and hence anything else caused by it, is dependent on the electrically continuous length of conductor in the magnetic field.
...
Ad infinitum!

Not being a competent mathematician, I have a problem in reconciling to a set of time-dependent entities being into a lumped constants K1, K1' and K2. Gut feel, but by your logic all motors and generators could have used 1 turn poles instead of multi-turn, and the alu former could have been the VC itself! Help, OEO!

[santosh.s]

DerAlte, first of all, my apologies for mis-understanding your statement earlier and blatantly opposing it- "More turns, more R, more Pdiss (R*I^2)". I read it by mistake as "For a given number of turns, more R means more Pdis" (and a proof is that I did not highlight "more turns" part when I quoted it last time). But then none of my posts/equations are going against that fact. If you increase R by adding more turns to the VC (or if you increase the number of rings in the other case), then damping has to be more, no two ways on this.

Anyways, rest of the discussion is interesting, so here it goes....

but the scene is not that bad that we have to discretize the parameters involved and make independent (and most likely incorrect) assumptions of 2nd and 3rd orders

I don't think there was any mistake in my assumptions. I did not really "discretize" any parameter, unlike what you are thinking. All I did was to analyze only an instantaneous condition, so as to isolate time. In fact, isn't that how differential equations like the one mentioned by you are derived? The differential equation explains what a sequence of ALL such instantaneous conditions sum upto, and how everything changes with time. I, for simplicity, considered only one such time instance, rather than all of them- which are infinite in number. I am absolutely not loosing on anything by doing that, as compared to what your differential equation would have explained (as far as the purpose of our argument is concerned- amount of damping- , of course!). Also, I agree with 4 points made by you, and I haven't ever gone against them.

"Discrete" analysis is fundamentally different in the sense delta-x or delta-t are not infinitesimally small as in my "instantaneous" case, they are FINITE, measurable and greater than zero. For example, in digital audio the time between two samples is discretization per se. BTW, I believe discrete system analysis is more complicated than analog domain, definitely not lesser.

I have a problem in reconciling to a set of time-dependent entities being into a lumped constants K1, K1' and K2.

These K's symbolize fixed parameter of the system like- length of the wire, magnetic field strength, velocity (being instantaneous) etc. - I am not brute forcing time dependent parameters into constants.

Gut feel, but by your logic all motors and generators could have used 1 turn poles instead of multi-turn, and the alu former could have been the VC itself! Help, OEO!

If that's what you concluded from my posts, then probably you did not read them as seriously as I would have expected you to. If that was the conclusion, then I would have doubted myself and checked my postings 100 times to find out mistakes. All I tried to prove was that a shorted VC having N turns with resistance R per turn should provide the same amount of damping as N separate turns (rings) with resistance R each. If you want to match the same level of damping with just one turn, then you have to make it much thicker and reduce its resistance to R/N.

Regarding speakers and motors with 1 turn, yes one can make such transducers and they will work too. But the difference would be that they will need much more current and less voltage to operate at the expected levels. It will be something like converting home appliance (high voltage, low current) to operate with car electricals (low voltage, high current), and you would probably need 0-gauge wires to drive them too! In short, practically there are more turns due to similar reasons for which transformers are required in electric world and gearboxes in mechanical world.

Once upon a time, I had made such a funny, practically useless DIY. I mean a "driver", not "enclosure" as it is almost implied in audio DIY community. When I read about the basic principle of a loudspeaker's working for the first time, I felt like it wasn't so complicated and that I could easily make one such device. So, I took a small plastic casing, attached a small steel/iron cap (bottom plate of a dry cell) on one side, made an electromagnet with an iron nail and "N" turns of a fine wire, mounted it as close to the steel plate as possible but without touching it (this part was quite tough). Connected the coil to headphone jack of a walkman, expecting it to reproduce the song. And it did indeed produce sound to make me happy, albeit at a very very low level. I could clearly recognize lyrics when holding it next to my ear... ahaa... I wasn't so familiar with a term called SQ then! Much later I realized that it could have been called (probably) a form of planar electromagnetic speakers. One turn speaker should be something like this one, I guess.

[low_bass_makker]

Originally Posted by santosh.s

Regarding speakers and motors with 1 turn, yes one can make such transducers and they will work too. But the difference would be that they will need much more current and less voltage to operate at the expected levels. It will be something like converting home appliance (high voltage, low current) to operate with car electricals (low voltage, high current), and you would probably need 0-gauge wires to drive them too! In short, practically there are more turns due to similar reasons for which transformers are required in electric world and gearboxes in mechanical world.

Once upon a time, I had made such a funny, practically useless DIY. I mean a "driver", not "enclosure" as it is almost implied in audio DIY community. When I read about the basic principle of a loudspeaker's working for the first time, I felt like it wasn't so complicated and that I could easily make one such device. So, I took a small plastic casing, attached a small steel/iron cap (bottom plate of a dry cell) on one side, made an electromagnet with an iron nail and "N" turns of a fine wire, mounted it as close to the steel plate as possible but without touching it (this part was quite tough). Connected the coil to headphone jack of a walkman, expecting it to reproduce the song. And it did indeed produce sound to make me happy, albeit at a very very low level. I could clearly recognize lyrics when holding it next to my ear... ahaa... I wasn't so familiar with a term called SQ then! Much later I realized that it could have been called (probably) a form of planar electromagnetic speakers. One turn speaker should be something like this one, I guess.

Very correct. the best example is the starter of a car. it has very few turns but very thick wire. Because we dont need speed there we need power.

The speakers are made with a bit practical approach, so that they can be efficient , the thing you did will also produce sound but it will not be efficient or even have a linear response.

Ever tried a DC motor or a transformer kept close to a magnet connected in place of a speaker, they also produce music but at a very low level.

[DerAlte]

Originally Posted by santosh.s

I don't think there was any mistake in my assumptions. ... ever gone against them.
...
All I tried to prove was that a shorted VC having N turns with resistance R per turn should provide the same amount of damping as N separate turns (rings) with resistance R each. ...

Once upon a time, I had made such a funny, practically useless DIY

I bow my head to you, OEO! Shabash, you have demonstrated perfect scientific temperament. Now that we have the "implicit" parts past us, what you have been saying makes a lot of sense. I had missed taking the example of squirrel-cage motors, which is better understood by your logic.

Most of us have done our simple-minded 'product development', not realizing that they were in fact post-facto proof of someone else's product. Your 'product' was in fact the 'speaker' transducer in the handsets of old rotary telephones, albeit with the mechanical parameters not under control.

I had, during engineering studies, goofily attempted to make "flat speakers" out of thin plywood and telephone 'transducers'. The 'surround' was strips of cycle-tube! That gave me *some* lessons in material properties and system behaviour, e.g. when excursion was high, the blasted thing would either stick to the pole or move completely out of range. Those speakers never 'spoke', but, it was lot of fun in learning!!!

[navin]

It's been a long time since I did not feel like the only geek on the planet.

[DerAlte]

Originally Posted by navin

It's been a long time since I did not feel like the only geek on the planet.

You're most welcome, Old man of ICE!

It's all stuff that we file away as useless when we get it, but need desperately the day basics are needed to resolve anything.

[santosh.s]

Originally Posted by low_bass_makker

Very correct.

Originally Posted by DerAlte

Now that we have the "implicit" parts past us, what you have been saying makes a lot of sense.

Great!.... that means the physics textbook served it's purpose.
Limewater, so, where were you?......BTW, are you still following?

Sorry, I have got this bad habit of hijacking threads because I never feel like creating new ones myself, due to an unpleasant experience with my very first thread!



The first thread I am talking about was related to a modification to the "better than merc s-class" A/C in my car, which I thought should be a trivial matter for those who go to great lengths modifying their cars- like adding cold air intake, changing cam-shafts, gearboxes, even engines and what not. But actually I ended up irritating a few guys who felt like it was a nonsense, and that my assumptions were wrong to begin with. Somehow, I managed to convince them about what I was saying, but then the activity stopped thereafter LBM/DerAlte/Navinji you may want to have a glance (??), it is located at:
http://www.team-bhp.com/forum/techni...eater-off.html

[DerAlte]

Originally Posted by santosh.s

Great!.... that means the physics textbook served it's purpose.

Careful, physics textbooks should be used sparingly for engineering topics - they provide negative acceleration to understanding. Technology and engineering build upon the concepts proposed by science to provide practical application, so one does not have to explain how bricks are made to explain architecture.

Originally Posted by santosh.s

Limewater, so, where were you?......BTW, are you still following?

Avoiding bheja-fry geek-talk like plague, I guess, and leading a normal healthy life, bless him. We don't know whether the "Limewater" handle refers to Ca(OH)2(aq) or Citrus aurantifolia+aqua,but in either case such talk would have a distinct clouding effect on the solution.

Originally Posted by santosh.s

Sorry, I have got this bad habit of hijacking threads because I never feel like creating new ones myself, due to an unpleasant experience with my very first thread!...LBM/DerAlte/Navinji you may want to have a glance

OEO, having spent most of my working life dealing with reqs and specs, I have learnt the hard way that understanding is directly proportional to clarity of expression, especially with as ambiguous a language as English! [Works better in German, but even there E has made in-roads (e.g. "gemanaged" is the G participle for "managed" - simply add "ge-" prefix to an E verb to make a G verb participle; "gesteuert" is archaic and fallen from favor, "gemanaged" is fashionable)]

That was my allusion to the "implicit". Since the speaker and the audience have different thought processes and reference points, normally the onus is on the speaker to create the reference points clearly for sync. In most conversations, the ref pts are implicit - so much so that one faces comical situations with "OmG, I thought you were talking about ..." - looking London, going Tokyo!!! The audience can at most take responsibility for missing reading a part of the speaker's expression.

[Lifewater]

Originally Posted by santosh.s

Limewater, so, where were you?......BTW, are you still following?

Yeah Yeah Santosh Collecting a lot of gyan. BTW I have fitted the sub by connecting a single VC and leaving the other VC free not shorted. I listned to the sub by shorting the free VC terminals and did not like the sound at all. The sub is in an enclosure and By jove tested to see how loud it plays --- it just rocks seems it will blow off my santro. THANKS Navinji. BTW please carry on your discussions a lots of fundas and theories are being cleared.

[navin]

Originally Posted by Lifewater

Yeah Yeah Santosh Collecting a lot of gyan. BTW I have fitted the sub by connecting a single VC and leaving the other VC free not shorted. I listned to the sub by shorting the free VC terminals and did not like the sound at all. The sub is in an enclosure and By jove tested to see how loud it plays --- it just rocks seems it will blow off my santro. THANKS Navinji.

Shorting the second voice coil does add damping lowers Qts and hence sometimes offer a more natual bass buuuuttt this damping esp with subs with big Mms makes the soun sound a little "funny".

To be honest I tried this as well and could not put my finger on it but the voice coil open sounded less "distorted" than the voice coil short. The distortion I talk about is not 2nd and 3rd order distortion but distortion menaing that the "sound deviated more from the input" than otherwise.

[low_bass_makker]

Hey, maybe we can exploit that! Actually, we can...
Say you want to use our Shiva driver. Say you like everything about it (especially the massive Xmax!), but
for your intended application, you want a higher Q. Well, this is the way: drive one voice coil. But rather
than just shorting the second coil, or leaving it open, terminate it with a resistor. The result? The Qts of
the driver will change from the open to the shorted Qts as the resistance is decreased. That means you can
tune the Q of the driver, with nothing more than a potentiometer!
In fact, for our Shiva subwoofer, operation in this mode allows one to literally dial in a Qts from ~0.4 to
~0.80. Now THAT'S flexibility! So a dual voice driver is actually amazingly flexible. Much more so than
usually pushed. Use a dual voice coil driver, and you can use a much wider range of enclosures, and even
have a system that can have a "Qts" knob on it, for changing the Qtc of a sealed system on the fly,
according to your tastes.

Taken from Adire audio website.

[navin]

Originally Posted by low_bass_makker

Taken from Adire audio website.

Hey I thought Dan closed Adire for lack of funds.