Re: absolutely OT
It happens quite often in audiophile reviews. 😀
(Imagining a double blind test of bikes...)
Edmond Stuart said:
It happens quite often in audiophile reviews. 😀
(Imagining a double blind test of bikes...)
The cat's out of the bag now, Edmond! I can't wait to read the next Keith Howard piece in Stereophile, exploring the Coriolis effect in amplifier output stage distortion.
🙄
🙄
Here's to not falling over.
My physics is getting pretty rusty, but I think in cycling you have to consider the effect of the angular momentum of the wheels during a turn. The way I see it, when Jan leans to the right, the frame of his bike leans to the left (maintaining the position of the COG). However, the angular momentum of the wheels resists this movement, resulting in an opposing force shifting the COG to the right, which in turn allows Jan to accelerate in that direction. As a side benefit, the front wheel processes and helps turn the wheel to the right. Of course, you could accelerate this process by initially turning to the left.
I’m not sure how much this has to do with electronics, but it helps keep Jan from falling on his keister. We wouldn’t want that to happen! 😉
Looney
My physics is getting pretty rusty, but I think in cycling you have to consider the effect of the angular momentum of the wheels during a turn. The way I see it, when Jan leans to the right, the frame of his bike leans to the left (maintaining the position of the COG). However, the angular momentum of the wheels resists this movement, resulting in an opposing force shifting the COG to the right, which in turn allows Jan to accelerate in that direction. As a side benefit, the front wheel processes and helps turn the wheel to the right. Of course, you could accelerate this process by initially turning to the left.
I’m not sure how much this has to do with electronics, but it helps keep Jan from falling on his keister. We wouldn’t want that to happen! 😉
Looney
Above a critical speed, a motorbike is even prone to dangerous oscillations of the front wheel.
john curl said:
That's like asking me if I can ski an icy, black mogul run in a white-out. I've never tried. I suspect I can get to the bottom of it but it may take some time and I might incur some serious bruising.
gyro
I did have Eric Laithwaite (gyroscope supremo) as a lecturer - what a brilliant guy, extremely accessible genius. I have a feeling you might like this article, John: the harder they fall
Brian
I'm having these images of postal workers across the world physically struggling to deliver parcels containing gyroscopes.
john curl said:
Hello John
What did he prove, my understanding was that he mentioned Otala in article on the distortion caused by undegenerated diff input opamps, and that when they are feed with large input signals ( frquency and amplitude) that feedback cannot correct the error. Further in the article he mentions the current conveyor topologies and how their input stage is far more linear and do not produce as much distortion when the input signal changes abruptly. But he finishes by saying that this problem with with diff pair inputs can be solved with degenertaing the input pair with a resistors.
But to this day tha lowest THD Audio opamp Analog Devices (where Barrie Gilbert works) makes is the AD797 and this does not have a degenerated diff pair input stage.
Regards
Arthur
John,
I'm surprised you approve of an op-amp that uses internal NFB to improve its spec sheet.
Brian
I'm surprised you approve of an op-amp that uses internal NFB to improve its spec sheet.
Brian
traderbam said:
You'll never know what's under the plastic hood 😀 LM6172 and LM7171 from National are internally current feedback.
By the way, computer monitor is a horrible thing for feedback: I almost lost vision especially of small details on dim light, now are training my eyes so they re-learn to apply feedback. I can solder and read without reading glasses again.
Re: 1500V
As an apprentice I leaned right over my cluttered workbench to reach something, supporting my weight with my right hand, placed down on top of the fins of a huge selenium full wave rectifier of a old Marconi valve regulated power supply.
Unfortunately it was plugged in and there was ~1500V across those fins. My rubber soled safety boots were doing a good job and I really didn't want to touch anything with my other hand at that time, so I held my left arm in the air, balancing myself so that I wouldn't roll over or fall into the supply proper.
Once balanced, with probably half my weight pushing down on that rectifier, I then had to lift/push myself up upright and back onto my feet with my right arm, forcing those fins to push harder into my palm and fingers.
I was a bit white after that, and my fingers didn’t feel too good either.
Edmond Stuart said:
As an apprentice I leaned right over my cluttered workbench to reach something, supporting my weight with my right hand, placed down on top of the fins of a huge selenium full wave rectifier of a old Marconi valve regulated power supply.
Unfortunately it was plugged in and there was ~1500V across those fins. My rubber soled safety boots were doing a good job and I really didn't want to touch anything with my other hand at that time, so I held my left arm in the air, balancing myself so that I wouldn't roll over or fall into the supply proper.
Once balanced, with probably half my weight pushing down on that rectifier, I then had to lift/push myself up upright and back onto my feet with my right arm, forcing those fins to push harder into my palm and fingers.
I was a bit white after that, and my fingers didn’t feel too good either.
Kind of reminds of the time in the military when I put my hand out to steady myself . . . on the top plate of one of those portable gas lamps . . . . I had a 3 inch ring branded into the palm of my hands that took weeks to heal.
Here's another good one. An electrician gets up a 10 foot ladder to do some work on a PA system - you know the systems that use a step down transformer at each speaker. He has to re-make some conncetions on the primary side of the transformer. Instead of coming down the laddrer to ge t some wire strippers, he decides to use his teeth. Just then, someone decides to make an announcement . . . .
Here's another good one. An electrician gets up a 10 foot ladder to do some work on a PA system - you know the systems that use a step down transformer at each speaker. He has to re-make some conncetions on the primary side of the transformer. Instead of coming down the laddrer to ge t some wire strippers, he decides to use his teeth. Just then, someone decides to make an announcement . . . .
Wavebourn said:
Hello Wavebourn
How do you retrain your eyes I am interested.
Regards
Arthur
PHEONIX said:
First of all Arthur, I've discovered more than 100 years' old theory of how eyes work developed by Dr. William Bates. According to what is taught to modern medics, a soft eyeball is stable, but hard lens changes it's shape. According to Bates, the soft eyeball changes it's shape, but a hard lens does not. It is logical. And it explained observations of American Indians who had perfect vision being very old, and of Bates' patients who he prescribed glasses to. Patients were loosing their vision progressively. When he discovered how eyes work he started teaching people to train their eyes again to return their vision.
First of all, muscles and nerves must work. That means, limiting movements of eyes de-train them; learning to see everything on the same distance (a book, a monitor) de-train them; seeing everything always equally lighted does the same harm.
That means, all glasses including sunglasses limit usage of eyes, so have to be avoided.
And second, exercises and relaxations are needed.
However though it is about feedback, it is not about feedback in Blowtorch preamp, so let's hope John forgiveth us for the heresy.
Wavebourn,
That's really interesting. I guess the eyes work kind of like the ears. Many people develop hyperacusis (Increased sensitivity to certain sounds) because they spend lot of time indoors, and in offices with sealed windows. And there ears don't get the practice they need with many sounds (conditioned reflexes need practice). So, some sounds start to become irritating or hurt their ears.
Early treatment involves just gradually listening more to loud sounds that don't bother them. This helps desensitize their ears. But it often gets more complicated than that. So, I'm kind of doing the same you are except with the ears. 😀
That's really interesting. I guess the eyes work kind of like the ears. Many people develop hyperacusis (Increased sensitivity to certain sounds) because they spend lot of time indoors, and in offices with sealed windows. And there ears don't get the practice they need with many sounds (conditioned reflexes need practice). So, some sounds start to become irritating or hurt their ears.
Early treatment involves just gradually listening more to loud sounds that don't bother them. This helps desensitize their ears. But it often gets more complicated than that. So, I'm kind of doing the same you are except with the ears. 😀
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