If you put a capacitor in series you lose the other advantages. The design question is how much power does the resistor have to dissipate to reduce the flux leakage in the otherwise unloaded transformer?
Anyone care to guess the other advantage of wasting a bit of power?
they could, I would expect that would allow faster charging and improve battery capacity
hehe 350K difference.. I guess you would really have to value your appearance of saving the planet.
horrid ostentatious colour too
hehe 350K difference.. I guess you would really have to value your appearance of saving the planet.
horrid ostentatious colour too
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Thanks for the link John, really enjoyed that talk.
Good to hear my take on mains leads from a top industry enginner 😀
BTW - this is true at most any frequency if loud enough... the ear will loose sensitivity, compress. The affect starts with the high freqs most.
An easy way for many people to experience this is at a concert with a PA for re'inforcement'. Before the concert, the background music thru the (EQ'ed) PA sound is shrill... a lot of HF boost. During the concert, the sound seems balanced. That's when you should leave or stick ear plugs in your ears. When the ear clamps down and attenuates the high freq, it is way to loud.
If you put your fingers in your ears for a minute, the ear raises its HF sensitivity and so when you take your fingers out of your ears, you hear it shrill again and it takes only a second or two-three for the ear to atten and clamp down on the highs where the sound balance is flat sounding again (because it was EQ'ed at full blast levels). Of course the people around you are looking at you as a moron for doing this but I still have some of my HF hearing. 🙂
-RNM
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The point I was making, is that we can't hear the U/S at all, but we do experience a physiological effect. Measuring a physiological response (MRI or EEG) does not equate to hearing.
My own experience was the reduction of background noise during the U/S exposure.
So, to me, being able to tell when Ed's 30 Khz signal is present is in fact, a no brainer..
A regime where I am indeed... an expert...😉
jn
Your point was clear to me.
I just added another dimension to the same mechanism.... compression of the high freqs at high acoustic levels (even if not registered in the brain). same result - reduction of background level (noise).
Ref can be found in audiology studies.
-RNM
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Do they now, over what frequency range? Years ago as Media Lab liason I helped out the Audio Spotlight guy (pre-startup, he had to graduate). I always questioned how the 100's (literally) of watts of ultrasound that it took to exploit the non-linearity of air would fly past OSHA.
EDIT - Joe is still at it... http://www.holosonics.com/?gclid=CIfWrYGF2rcCFUJqMgod1QUAlQ
The systems they sell are modest but a significant portion of the 65W quoted is radiated ultrasound.
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No, I do not. It was a result of personal experience. Within a production high noise environment, a person 10 feet behind me was using an ultrasonic welder to staple superinsulation layers. Every time he pushed the power button, the background noise went down. Pumps, compressors, fans, motors, they all got quieter.
Once I realized the connection, I had him turn it on at random while I was back turned to him, and I would raise my hand when the background quieted down. It proved the connection.
You mean the "no-brains" expertise? I thought everybody knew that...
jn
I am not aware of any exposure limit changes within OSHA. When I broached the issue to the safety guys here because of my hearing damage concerns, they had no idea how to either approach or measure it. Bottom line was, we decided to use over the ear hearing protection even though we had no way of knowing if they actually protected us. All they could do was measure using A weighting. Unfortunately, the weighting is geared to low level sound audibility, not towards measurement of high level sound energy which may damage hearing, and the weights drop fast in the 10k and up range.
I suspect total delivered energy to the eardrum should be the metric. However, I have no data to support that suspicion. I note that it is easier to deliver energy to the eardrum at shorter wavelengths than at long.
Yah, that hundreds of watts of U/S thing...holy mackeral.. I cringed when I first read about that. Seemed to be about as smart as using a magnetron for home heating.
jn
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When one guy I know was given the royal show-and-tell by Woody Norris, he was in close proximity to one of the transducers and reported some discomfort then, and a headache thereafter.
In a somewhat-breezy article by van Maanen which references one of Norris's TED talks, in Linear Audio volume 5*, it's asserted that the ear has 25% distortion (no levels or frequency range specified), with the discussion following giving the implication that this is how Woody's gizmos work. But we know that a good deal of the effect is due to the nonlinearity of the medium, i.e., the air. Energy is there at the difference frequencies independent of nonlinearity of the receiver.
*On the audibility of "high-resolution" digital audio formats and how to test this
In a somewhat-breezy article by van Maanen which references one of Norris's TED talks, in Linear Audio volume 5*, it's asserted that the ear has 25% distortion (no levels or frequency range specified), with the discussion following giving the implication that this is how Woody's gizmos work. But we know that a good deal of the effect is due to the nonlinearity of the medium, i.e., the air. Energy is there at the difference frequencies independent of nonlinearity of the receiver.
*On the audibility of "high-resolution" digital audio formats and how to test this
Interesting. I called the safety guys because one of the operators was experiencing headaches..
jn
When the ultrasonic heterodyne transducer of Norris failed to captivate the audio community ("doesn't suffer from all the problems of conventional loudspeakers..." yada yada) the indefatigable man found applications in anti-personnel weaponry.
jneutron,
I don't have the attenuation chart for the over ear sound barriers but I would suspect that the high frequencies are the most attenuated of the entire band. You can still hear someone talking to you very easily with the ear protection. I bought my last set for shooting at the gun range and they do work rather well.
I wonder about the level of low frequency output and sub sonic output at concerts these days as so much electronic music has the bass frequency level bumped up so loud these days.
I don't have the attenuation chart for the over ear sound barriers but I would suspect that the high frequencies are the most attenuated of the entire band. You can still hear someone talking to you very easily with the ear protection. I bought my last set for shooting at the gun range and they do work rather well.
I wonder about the level of low frequency output and sub sonic output at concerts these days as so much electronic music has the bass frequency level bumped up so loud these days.
but does it need to go through the ear at all at such HF? or is it more of a bone conduction jobbie? that would surely make the over the ear protection somewhat less effective.
I have been to several demos of the gadget. It neat, not audiophile at all and I don't think they know how it works. In the demos the sound always emanated from the surface it reflected off of. I think the IM process is only at the reflecting surface, not in air at all. Thats why its a good secure ship to ship communicator.
qusp,
I was always under the impression that it was the lower frequencies that use bone conduction?
I was always under the impression that it was the lower frequencies that use bone conduction?
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