Power cable and audio signal cable parallel proximity - Page 2 - AVS Forum
Forum Jump: 
Reply
 
Thread Tools
post #31 of 51 Old 07-20-2012, 05:09 AM
AVS Addicted Member
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 13,654
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 288 Post(s)
Liked: 997
Quote:
Originally Posted by has7738 View Post

Transformers can still win, though, because they can be operated without a ground reference, thus busting the ground loop. Galvanic isolation, and all. Even a cruddy transformer does that.

Right. If you want to deal with a common mode voltage in the range of a few 100's of volts or a KV or two, transformers provide a very economical solution. The bench performance of the transformers in < $20 ground isolators is really pretty good if you use them intelligently.
arnyk is offline  
Sponsored Links
Advertisement
 
post #32 of 51 Old 07-20-2012, 05:54 AM
AVS Special Member
 
SAM64's Avatar
 
Join Date: Apr 2011
Posts: 1,563
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 68
Quote:
It takes a ferrous metal with high permiability, ideally Mu-Metal, to redirect a magnetic field away from something.

that's what I learnt in university.....wait till the hobbiests come by and tell you you're wrong though wink.gif
SAM64 is offline  
post #33 of 51 Old 07-20-2012, 06:17 AM
AVS Special Member
 
jneutron's Avatar
 
Join Date: Mar 2007
Posts: 1,879
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Quote:
Originally Posted by has7738 View Post

Whereas an AC magnetic field, or any magnetic field for that matter, can't be stopped by a copper or aluminum shield.

Actually, that is not entirely accurate. (and no, not area 51).

Many confuse this issue. (note, I will use "B-dot" in place of the phrase time varying magnetic flux"...)

At the "micro" level:

Skin depth/Lenz exclusion will reject the penetration of a B-dot intrusion. The currents that are generated in a conductive surface with B-dot field lines normal to the surface generate eddy currents. These eddy currents will create a B-dot field which is opposite of the penetrating flux, so will attempt to cancel the penetration. Because this exclusion is dependent on material conductivity and thickness, for normal conductors and low frequency, it is not very effective. For superconductors, it works perfectly, total exclusion results as long as the induced currents do not exceed the material's critical current density times it's cross sectional area. Above that, the super will quench.

At the "macro" level:

Faraday's law of induction describes the voltage that will be present within a loop of conductor that traps a B dot field. When a shielded cable forms a closed loop, both the shield AND the core conductor will have a voltage generated on them as a result of trapped B dot. For the core wire, the current induced will be dependent on the impedance of the overall loop, a typical input will make that 10K ohms give or take. The shield however, is a very different story. The current induced on the shield will create it's own magnetic field, the level of current will depend on the loop impedance, and the field created will be 180 degrees out of phase with the B dot field which was trapped. (This is described well in IEEE-STD-1050, but uses the terms agressor and victim.)

If one can make the loop with sufficiently low impedance such that the cancelling field is equal to the inducing field, then shielding is complete...using a superconducting shield loop for example. The problem with this is..how does the equipment deal with these currents? Both the source and load gear will now have ground loop currents flowing, and they in turn can create B dot fields INSIDE the equipment.

While your statement is indeed accurate at the micro level, at the system level, it is incorrect.
Quote:
Originally Posted by has7738 View Post

It takes a ferrous metal with high permiability, ideally Mu-Metal, to redirect a magnetic field away from something. Cables don't use mu-metal shields because the darn stuff isn't flexible. It's a nickel-iron alloy that gets heat treated and ends up pretty hard and brittle. Makes for good tube shields and transformer shields, but lousy around wire.
Unless of course, you are making old style transatlantic cables.smile.gif.

Mu metal saturates easily, so it's always wise to consider the maximum fields being excluded. Sometimes, multiple layers are needed. I can't use it at work, field levels are too high. Even normal steel saturates above 1.5 tesla.
Quote:
Originally Posted by has7738 View Post

Transformers can still win, though, because they can be operated without a ground reference, thus busting the ground loop. Galvanic isolation, and all. Even a cruddy transformer does that.
Quote:
Originally Posted by arnyk View Post

Right. If you want to deal with a common mode voltage in the range of a few 100's of volts or a KV or two, transformers provide a very economical solution. The bench performance of the transformers in < $20 ground isolators is really pretty good if you use them intelligently.
Agreed. I'm building a mobile rig for my daughter, laptop driven, so I'm going to include two input sets(one redundant) both transformer isolated, it doesn't get any better than that..

jn

Some discuss because they can. Others attack because they cannot. (unknown attribution)
A good man knows his own limitations...(Dirty Harry)
Lead, follow....or get out of the way..
jneutron is offline  
post #34 of 51 Old 07-20-2012, 06:25 AM
Senior Member
 
has7738's Avatar
 
Join Date: May 2012
Location: North America
Posts: 297
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 24
Quote:
Originally Posted by arnyk View Post

Right. If you want to deal with a common mode voltage in the range of a few 100's of volts or a KV or two, transformers provide a very economical solution. The bench performance of the transformers in < $20 ground isolators is really pretty good if you use them intelligently.

Right, my favorite PC Buzz fix is that ground isolator blob from Radio Shack...two xfmrs in one blob, RCA cables and everything, about $20. I keep them in stock, ready to go. And don't tell anyone, but they sound good too so long as you stay in the consumer level world. Ok, here's the number: 270-054. Every go buy them out again.

The problem with using a transformer with a kV of common mode on it is that CMRR is a ratio, so if that's a line level circuit, even with anything but a really good transformer the noise could be audible. That one's a real problem, just not enough low cost rejection in the world to beat down that much input voltage below audibility. Now if you've got a volt of CM and anything with 100dB of CMRR, you've got a win. Not with 30dB more CM to kill though, and if that voltage is even 3KHz, you're done. As an example, a really good mic input transformer like the JT-16-A specs 117dB of CMR at 60Hz, 85dB at 3KHz. He doesn't publish the CMRR curve, but it gets worse as frequency goes up. If this is a mic input, even with 117dB of CMR and 1V of CM you could have an audible problem. So it's not only what the CM voltage is, but what it's frequency is too. Of course 1kV would render an active circuit inactive, even if applied for...well, as fast as you could connect and disconnect an XLR. Heck, a connection spike with 48V of phantom power on a mis- wired XLR doesn't do an active input any good, which is why there's usually a DC clamp to save it's bacon.

But as an example of high CMRR being needed, and an active input applied, consider an EKG or ECG system where you've got this big old body out on the end of it acting like a massive antenna in a world of all sorts of EM fields, but the signals you want are micro volts and fairly low frequency. They all use in-amps. Of course medical equipment costs about a million times that of audio gear on a per-part basis, so what the heck, whip up a custom in-amp and don't electrocute the patient. Messes up their whole day.
has7738 is offline  
post #35 of 51 Old 07-20-2012, 06:33 AM
AVS Special Member
 
jneutron's Avatar
 
Join Date: Mar 2007
Posts: 1,879
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Quote:
Originally Posted by has7738 View Post

Right, my favorite PC Buzz fix is that ground isolator blob from Radio Shack.

Agreed. They work very nicely. I've QA concerns with RS, but price is good...
Quote:
Originally Posted by has7738 View Post

and don't electrocute the patient. Messes up their whole day.

Well, at least there wouldn't be any customer complaints..

jn

Some discuss because they can. Others attack because they cannot. (unknown attribution)
A good man knows his own limitations...(Dirty Harry)
Lead, follow....or get out of the way..
jneutron is offline  
post #36 of 51 Old 07-20-2012, 06:38 AM
AVS Special Member
 
jneutron's Avatar
 
Join Date: Mar 2007
Posts: 1,879
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Quote:
Originally Posted by SAM64 View Post

that's what I learnt in university.....wait till the hobbiests come by and tell you you're wrong though wink.gif
Well, I kinda dispelled that. High conductivity materials certainly do it as well. And it doesn't have to be niobium titanium or niobium tin either. Really good annealed copper has electrical conductivity over two orders of magnitude better that it's room temperature conductivity in the 2 to 4 kelvin temperature range, yet has a permeabiliy extremely close to free space.. (mean free paths on the order of 4 to 10 centimeters).

But I guess since I do magnetic field goop for a living, I'm probably not in the "hobbyist" category.

jn

Some discuss because they can. Others attack because they cannot. (unknown attribution)
A good man knows his own limitations...(Dirty Harry)
Lead, follow....or get out of the way..
jneutron is offline  
post #37 of 51 Old 07-20-2012, 06:48 AM
AVS Addicted Member
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 13,654
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 288 Post(s)
Liked: 997
Quote:
Originally Posted by has7738 
But as an example of high CMRR being needed, and an active input applied, consider an EKG or ECG system where you've got this big old body out on the end of it acting like a massive antenna in a world of all sorts of EM fields, but the signals you want are micro volts and fairly low frequency. They all use in-amps. Of course medical equipment costs about a million times that of audio gear on a per-part basis, so what the heck, whip up a custom in-amp and don't electrocute the patient. Messes up their whole day.

If I understand EKG and EEG, the application is very different from audio in that the LF bandpass goes many octaves lower, and response to 20 KHz isn't even a thought.
arnyk is offline  
post #38 of 51 Old 07-20-2012, 06:52 AM
Senior Member
 
has7738's Avatar
 
Join Date: May 2012
Location: North America
Posts: 297
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 24
Quote:
Originally Posted by jneutron View Post

And it doesn't have to be niobium titanium or niobium tin either.agnitude better that it's room temperature conductivity in the 2 to 4 kelvin temperature range, yet has a permeabiliy extremely close to free space.. (mean free paths on the order of 4 to 10 centimeters).
But I guess since I do magnetic field goop for a living, I'm probably not in the "hobbyist" category.
jn

That settles it. I'm keeping my copper shielded wire and cranking my air conditioning down to 2 kelvin. Hope the wires still bend.

Come to think of it, hope I still bend.
has7738 is offline  
post #39 of 51 Old 07-20-2012, 06:58 AM
Senior Member
 
has7738's Avatar
 
Join Date: May 2012
Location: North America
Posts: 297
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 24
Quote:
Originally Posted by arnyk View Post

If I understand EKG and EEG, the application is very different from audio in that the LF bandpass goes many octaves lower, and response to 20 KHz isn't even a thought.

Right again, but it is a thought because there are some details in those LF signals they want to see, so you can't just brick wall filter above 10Hz, there is actually response in the 60Hz range, though it's been dealt with. I'm assuming too that modern machines use some form of digital conditioning, so I'm thinking of the old stuff.

I guess that EKG discussion is tangential anyway, but the point is that a well designed in-amp can have a flatter CMRR curve than any transformer. But again, not just any active input will do that, it has to be well designed. If you do a CMRR sweep test on the garden variety audio input you get a wicked curve that's optimized for 60Hz, then falls to pieces, transformer or active.
has7738 is offline  
post #40 of 51 Old 07-20-2012, 06:59 AM
AVS Special Member
 
SAM64's Avatar
 
Join Date: Apr 2011
Posts: 1,563
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 68
Quote:
Well, I kinda dispelled that.

yeah, 'kinda' wink.gif
SAM64 is offline  
post #41 of 51 Old 07-20-2012, 07:05 AM
AVS Special Member
 
jneutron's Avatar
 
Join Date: Mar 2007
Posts: 1,879
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Quote:
Originally Posted by has7738 View Post

That settles it. I'm keeping my copper shielded wire and cranking my air conditioning down to 2 kelvin. Hope the wires still bend.
Come to think of it, hope I still bend.

They will....you won't..smile.gif

That's one heck of an air conditioner...

jn..

ps...trivial fact.. kapton is the only insulator I'm aware of that remains flexible below 10 Kelvin..

Some discuss because they can. Others attack because they cannot. (unknown attribution)
A good man knows his own limitations...(Dirty Harry)
Lead, follow....or get out of the way..
jneutron is offline  
post #42 of 51 Old 07-20-2012, 07:06 AM
AVS Special Member
 
jneutron's Avatar
 
Join Date: Mar 2007
Posts: 1,879
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Quote:
Originally Posted by SAM64 View Post

yeah, 'kinda' wink.gif

Agreed. Unfortunately, no matter how high level or low level I make the technical details, some hobbyist will still indeed claim some silly thing..

jn

Some discuss because they can. Others attack because they cannot. (unknown attribution)
A good man knows his own limitations...(Dirty Harry)
Lead, follow....or get out of the way..
jneutron is offline  
post #43 of 51 Old 07-20-2012, 07:21 AM
AVS Special Member
 
jneutron's Avatar
 
Join Date: Mar 2007
Posts: 1,879
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Quote:
Originally Posted by has7738 View Post

Right again, but it is a thought because there are some details in those LF signals they want to see, so you can't just brick wall filter above 10Hz, there is actually response in the 60Hz range, though it's been dealt with. I'm assuming too that modern machines use some form of digital conditioning, so I'm thinking of the old stuff.

I would have assumed a notch at 60hz . Just looking at the waveforms, I'd think they'd want 10, 20, even 30 hz response for some details.

I don't think it's quite as bad as we're thinking however. The measurements are all fully differential, and they control the magfield coupling loop geometry by the lead bundle design.

jn

ps..interesting read...

http://www.eetimes.com/design/medical-design/4213140/Techniques-for-accurate-ECG-signal-processing

to wit, quotes from the article..neat stuff hilited..
According to the IEC specification, the bandwidth of the ECG required is from 0.5Hz to 150Hz

The main sources of noise in ECG are

•Baseline wander (low frequency noise)
•Power line interference ( 50Hz or 60Hz noise from power lines)
•Muscle noise (This noise is very difficult to remove as it is in the same region as the actual signal. It is usually corrected in software.)
•Other interference (i.e., radio frequency noise from other equipment)

This noise can be removed by the following methods:

•Isolate the front-end ground electronics from the digital system as much as possible. Effective system level design is extremely important in terms of the overall noise rejection.
•Use instrumentation amplifiers with very high common mode rejection ratios on the order of 100dB
Drive the patient body with an inverted common mode signal. The right leg of the patient is driven with a signal which is the inverted average of Lead_I, Lead_II, and Lead_III. Scaling the suitably prevents common mode noise from being coupled into the system.
•Shield the device using metallic shields to prevent high frequency RF from being coupled into the system.
•Use shielded cables to acquire the ECG which are driven with a common voltage to reduce noise from being coupled.
•Apart from the above methods, a number of software algorithms are present for the removal of noise after the signal has been acquired.

Power-line noise is removed by implementing a notch filter at 50/60Hz in the digital domain.

Some discuss because they can. Others attack because they cannot. (unknown attribution)
A good man knows his own limitations...(Dirty Harry)
Lead, follow....or get out of the way..
jneutron is offline  
post #44 of 51 Old 07-20-2012, 01:14 PM
Senior Member
 
has7738's Avatar
 
Join Date: May 2012
Location: North America
Posts: 297
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 24
EKG signals are mostly below 30Hz with the shortest period at 50ms (20Hz), though they may want some detail in the waveform, so probably bandwidth 2 or 3 times the shortest waveform period. But there are some EEG (gamma brain wave) signals in the 30-100Hz area. I keep all my brainwaves below 20Hz so my brain doesn't interfere with my subwoofer, and I don't have to think as fast.

Even lower at 2 Kelvin.
has7738 is offline  
post #45 of 51 Old 07-22-2012, 07:51 PM
Senior Member
 
danielrg's Avatar
 
Join Date: Jul 2011
Location: Salt Lake City, UT
Posts: 218
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 16
Quote:
Originally Posted by jneutron View Post

Exactly. Been there done that as well.
Back in 2004, I had to run unbalanced line level 125 feet from a stage amp to a balconysource. 450 seat venue, about 15 kw of solid state dimmer, a quarter million volt Van De Graf generator, a toro 700 leafblower, building HVAC, and a 12 phase 5 megawatt power supply a quarter mile away.
Ran a loooong extension cord to the mixer rack, wrapped a mic cable and the unbalanced line feeds to the stage around the extension cord. Eliminated ALL noise.
In my case, configuration C.

jn

I am trying to learn more about ground loops. I very much appreciated the diagram.

Question - would configuration "B" be good or bad? Looked pretty good to me... Is "C" even better?

Along the lines of ground loops, can current loops of large area in the AC power side (lighting or other power supply portions of a stage/theater) have a negative effect by generating excessive noise? In other words how power is routed for a bank of dimmer switches, where the neutral doesn't follow the hot around the circuit cause problems?

For example:



In this case, the supply to the light doesn't follow the same path as the return. Would the area of the loop possibly mean anything? I read that for noisy AC circuits (and indeed for most any AC circuit running through a "sensitive" area, the neutral should STAY with the hot throughout the route. Particularly if the dimmer is a solid state dimmer, chopping up the power waveform and creating nasty harmonics?

Would this be better:



Or just a waste of copper? I don't think many electricians would bat an eye at doing what's in the first picture. Is there any reason to do what's in the second picture? It takes significantly more wire and results in the same basic circuit... But does one behave better at avoiding injecting noise into the space? Especially with the idea of having a solid state dimmer on the circuit - one of the noted enemies of sensitive equipment...

So this question would be on the side of not generating noise, instead of how to reject noise that already exists. I'd assume a well designed stage/theater would do everything to minimize both the generation and the injection of noise into the area. Do any of these principles you have been discussing apply to reducing the generation of interference as well as rejecting it?

Electrical engineer by education. Currently a system engineer. I like home automation, theaters, and blinking lights.
Someday it'll be more of an actual hobby - if my employer would ever let me go home!
"The Escape Pod" - My First Theater Build
danielrg is offline  
post #46 of 51 Old 07-23-2012, 01:13 AM
Senior Member
 
has7738's Avatar
 
Join Date: May 2012
Location: North America
Posts: 297
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 24
The problem with dimmers is, as you mention, how they "chop up" the waveform to achieve dimming. However, these days most decent dimmers employ filtering to minimize the RFI they radiate. If you look at the specs on dimmers (if you can find them) you may find a figure that implies how much junk is spit out, usually a figure or two that imply a filter.

Either of your circuits would work. Just keep your lighting circuits and av equipment circuits isolated, don't share wiring or conduits. Keep everything AV separate from the dimmer circuits all the way back to the breaker, you should have no problems.
has7738 is offline  
post #47 of 51 Old 07-23-2012, 05:08 AM
AVS Addicted Member
 
arnyk's Avatar
 
Join Date: Oct 2002
Location: Grosse Pointe Woods, MI
Posts: 13,654
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 288 Post(s)
Liked: 997
Quote:
Originally Posted by has7738 View Post

The problem with dimmers is, as you mention, how they "chop up" the waveform to achieve dimming. However, these days most decent dimmers employ filtering to minimize the RFI they radiate. If you look at the specs on dimmers (if you can find them) you may find a figure that implies how much junk is spit out, usually a figure or two that imply a filter.
Either of your circuits would work. Just keep your lighting circuits and av equipment circuits isolated, don't share wiring or conduits. Keep everything AV separate from the dimmer circuits all the way back to the breaker, you should have no problems.

Also, many dimmers do chop, but they chop on zero crossings. This does not eliminate harmonics, but it is good for something like a 20 dB (10x) improvement over random chopping. The filters are still needed, but they have much less hash to trash.
arnyk is offline  
post #48 of 51 Old 07-23-2012, 06:16 AM
AVS Special Member
 
jneutron's Avatar
 
Join Date: Mar 2007
Posts: 1,879
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Quote:
Originally Posted by danielrg View Post

I am trying to learn more about ground loops. I very much appreciated the diagram.
Question - would configuration "B" be good or bad? Looked pretty good to me... Is "C" even better?

C is in essence, a subset of B. It just has the power amp and IC sliding along the power cord to the outlet.
Quote:
Originally Posted by danielrg View Post

I don't think many electricians would bat an eye at doing what's in the first picture. Is there any reason to do what's in the second picture?

Both arrangements are generally the same, the only diff being that very small loop in the junction box. If the junction box is a typical metal one, it is magnetic and will pretty much prevent that loop from splashing field external to the box. The most important thing is that both arrangements control the current very well. If you clamp a current probe around either the 25 foot or 40 foot cable runs, there is a net zero current. In my figure A, a current probe would measure ground loop currents, but in B and C, there will be no net current no matter where you put the clamp (as long as you encompass the AC and line level cord.)
Quote:
Originally Posted by danielrg View Post

So this question would be on the side of not generating noise, instead of how to reject noise that already exists. I'd assume a well designed stage/theater would do everything to minimize both the generation and the injection of noise into the area. Do any of these principles you have been discussing apply to reducing the generation of interference as well as rejecting it?
The principles apply to both. Essentially, the perfect transmitter is also the perfect receiver. There are very few exceptions to this rule.

Way back in the distant past, when dinosaurs ruled the earth, dimmer triacs were allowed to increase the line current without remorse. The current slew rate was not controlled, and was very high. Eventually, some cro-magnon organization came up with a slew rate specification to limit the frequency content of typical consumer light dimmers. But it is still a good idea to limit transmitting and receiving loops, and put as much distance between the circuits as is feasable as mentioned by has7738.

I've used quite a few zero crossing solid state switch modules for AC control, and dimmers, but I've never seen a zero crossing dimmer.

jn

Some discuss because they can. Others attack because they cannot. (unknown attribution)
A good man knows his own limitations...(Dirty Harry)
Lead, follow....or get out of the way..
jneutron is offline  
post #49 of 51 Old 07-23-2012, 08:15 AM
AVS Special Member
 
SAM64's Avatar
 
Join Date: Apr 2011
Posts: 1,563
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Liked: 68
Quote:
Also, many dimmers do chop, but they chop on zero crossings. This does not eliminate harmonics, but it is good for something like a 20 dB (10x) improvement over random chopping. The filters are still needed, but they have much less hash to trash.

You're referring to reverse phase dimming, which uses IGBT's as the switching element. They do switch on at the zero crossing, and then ramp down later in the waveform. They don't require inductive chokes like triac dimmers do...but then, I've never seen any reverse phase dimmers for consumer use.
SAM64 is offline  
post #50 of 51 Old 07-23-2012, 08:28 AM
AVS Special Member
 
jneutron's Avatar
 
Join Date: Mar 2007
Posts: 1,879
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 17
Quote:
Originally Posted by SAM64 View Post

You're referring to reverse phase dimming, which uses IGBT's as the switching element. They do switch on at the zero crossing, and then ramp down later in the waveform. They don't require inductive chokes like triac dimmers do...but then, I've never seen any reverse phase dimmers for consumer use.

Very interesting. I did find one manufacturer which requires reverse phase dimmers on their LED products due to leading edge transient voltage possibilities with normal triac based dimmers.

So there are consumer based ones. Apparently, it is very important to review the manu's information in order to select the proper type. sheesh, as if it's complex enough as it is.

I can certainly see how reverse would lessen all kinds of noise, acoustic and electrical for incandescents.. Leading edge turn on does so into a colder filament, which has less resistance, whereas trailing edge turnoff would be with the filament hottest. Less current is interrupted..

jn
Guess I'm not such an old dog...afterall:)

Some discuss because they can. Others attack because they cannot. (unknown attribution)
A good man knows his own limitations...(Dirty Harry)
Lead, follow....or get out of the way..
jneutron is offline  
post #51 of 51 Old 07-23-2012, 06:48 PM
Senior Member
 
danielrg's Avatar
 
Join Date: Jul 2011
Location: Salt Lake City, UT
Posts: 218
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked: 16
Thanks for all the great information. Now to find the right dimmers for the job! (Always a challenge)

Electrical engineer by education. Currently a system engineer. I like home automation, theaters, and blinking lights.
Someday it'll be more of an actual hobby - if my employer would ever let me go home!
"The Escape Pod" - My First Theater Build
danielrg is offline  
Reply Audio theory, Setup and Chat

User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off