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Old 19th March 2013, 01:45 PM   #8711
gootee is offline gootee  United States
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Sorry for the non sequitur. While not fully applicable, the following has some interesting sections on sound quality measurements.

http://cdn.rohde-schwarz.com/dl_down.../1MA202_1e.pdf
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Old 19th March 2013, 05:38 PM   #8712
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Unless I am being very dense gootee they don't exactly sell the product . I wish they would give an example of experimental use and data . Maybe they did and I lost the will to live whilst trawling through it ?

I feel I need Richard Feynman to make it accessible. I just watched how badly NASA treated him over the Challenger disaster . Like something they picked up on their shoes and worse , a Rookie . If the film is to be believed he was led up a blind ally and was grilled just as anyone here is . Here we can take it with a pinch of salt , their it was trust and truth .

Tinkering . For 23 years it was my life and I did it even when I didn't want to . It was required . I guess I only tinkered with something unrequested about 10 times in my life . Much of what is made is work in progress . Whilst repairing something the extra effort to make it work properly is nearly nothing . A famous make of amplifier had one design which maybe went to market unfinished ? A track carrying the feedback was too long and convoluted . Disconnecting the track and using a piece of 2.5 sq mm cable cured that . The customer had very accurately described the fault just before failure . It was not obvious and required certain things to happen to set it off . I seam to remember it had a marked effect on measurements . I didn't have a spectrum analyzer then , a Ferrograph test set . The tinkering was requested . Having done work like that for 23 years I can tell you design errors are the norm . I gave up that work in 1997 , I still do a bit for friends . I would bet 90% of products sold in shops can be dramatically improved by the careful use of a little commonsense engineering . As I said today I can not see how reinforcing the 0 V between PSU caps can do any harm . I can not see any circumstances where even if marginal it wouldn't be an improvement . The word impossible comes to mind . OK mistakes can be made . Some are born geniuses , others learn . If I don't know something is wrong my oscilloscope always does .
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Old 20th March 2013, 08:44 AM   #8713
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I'll drink to that.

Sometimes, it takes me weeks to even understand the original design schematic. Fiddling around without understanding it is more likely to cause trouble than to improve anything.
Most of my life was sorting out amplifiers and tape decks . Life was like a Vet , seldom just one thing ( Doctors only do humans ) . Usually phone the company , fax a circuit , ask where to start . Example Rotel . Nige pull out the outputs , usually the drivers have survived . Give it a test . Replace what's wrong . Reset Bias . 30 minutes and job done . Other designs were less happy . A vague idea and how a certain area was always in doubt . My feeling is rushed to market and usually Japanese . From memory all designs I modified did work better . I felt it important to get them reliable . Trio Kenwood and Rotel were the best . Naim Audio the very best . Armstrong seemed to have a good 3 years then pop . That is not the usual pattern . Pop seems to be any time if a weak design . Armstrong was perhaps just capacitors . I say perhaps as I still don't really know . They just seemed to let go . My brother designed a new set of transistors to replace the obsolete types . These seem better . Not really apparent why as the originals were superbly specked and even have cog heat-sinks . When I say a new set he really went to town checking how they would perform .

My brother tinkered with TV's . He made every 1950 , 60 , 70's TV's he saw often enough reliable . The old people locally knew this . He wrote in TV magazine sometimes . His favourite TV's were ITT . Mostly the reliability was down to very small things . He was ambivalent about Sony , it was neither good nor bad . He was very good at audio engineering although not his passion . He saw it all in TV's .

Last edited by nigel pearson; 20th March 2013 at 08:47 AM.
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Old 20th March 2013, 05:55 PM   #8714
a.wayne is offline a.wayne  United States
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Default Super capacitors

Graphene supercapacitors are 20 times as powerful, can be made with a DVD burner | ExtremeTech
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Old 20th March 2013, 06:21 PM   #8715
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If it was April 1st I would have doubts . My fist thoughts were the laser doesn't cover the whole surface so how come we get the real deal Graphene ? But what would I know ? I dare say we might get something useful ?

Graphite oxide + water + laser = breakthrough. - YouTube
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Old 20th March 2013, 11:18 PM   #8716
fas42 is offline fas42  Australia
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Very useful in fact. Imagine a pure electric car with a range of 300 miles, and conventional automotive performance, where you can drive into a "filling station" and recharge your batteries in the same time as you take now to fill the tank with petrol ...

Frank
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Old 21st March 2013, 03:04 AM   #8717
benb is offline benb  United States
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I heard something about this when sitting in on a basic electronics class (I'll be teaching one in a few weeks). The teacher was trying to explain capacitors, and the student was asking about this, trying to tell the news story about how a graphene capacitor could replace a battery. It makes sense (especially after the video) now (I think).
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Very useful in fact. Imagine a pure electric car with a range of 300 miles, and conventional automotive performance, where you can drive into a "filling station" and recharge your batteries in the same time as you take now to fill the tank with petrol ...

Frank
I can see it now, and I recall mentioning this before in a previous discussion on (theoretical) fast-charge electric cars. Every electric filling station will need to be an electric substation because of the huge amount of power needed for fast charging. A residential KWH meter would fly apart from spinning so fast.

On the other hand, a large bank of such capacitors could make for a near-perfect (and in very efficient) load-leveling storage device - charge it up during daylight and/or high wind with solar cells and wind generators, and discharge it into the grid at night when people are cooking dinner, watching TV, doing laundry and fast-charging their electric cars (or pulling 100+ amps from their 200 amp service to charge their car in an hour or two).
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Old 21st March 2013, 03:19 AM   #8718
bcarso is offline bcarso  United States
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Quote:
Originally Posted by benb View Post
I heard something about this when sitting in on a basic electronics class (I'll be teaching one in a few weeks). The teacher was trying to explain capacitors, and the student was asking about this, trying to tell the news story about how a graphene capacitor could replace a battery. It makes sense (especially after the video) now (I think).

I can see it now, and I recall mentioning this before in a previous discussion on (theoretical) fast-charge electric cars. Every electric filling station will need to be an electric substation because of the huge amount of power needed for fast charging. A residential KWH meter would fly apart from spinning so fast.

On the other hand, a large bank of such capacitors could make for a near-perfect (and in very efficient) load-leveling storage device - charge it up during daylight and/or high wind with solar cells and wind generators, and discharge it into the grid at night when people are cooking dinner, watching TV, doing laundry and fast-charging their electric cars (or pulling 100+ amps from their 200 amp service to charge their car in an hour or two).
Feynman has a wonderful discussion of what really happens when we charge a capacitor, I think in his epic Lectures on Physics (with Leighton and Sands). It is not as simple as it is often suggested.
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Old 21st March 2013, 05:43 AM   #8719
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Some of the wilder energy densities talked about are similar to tnt. You would not want to be in an accident with one in your car
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Old 21st March 2013, 07:17 AM   #8720
dvv is offline dvv  Serbia
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Not to throw a wrench into the machine, but as I have been led to believe, charging batteries involves a compromise. Charging them slowly takes more time but prolongs their service life, and charging them fast takes less time but also shortens their useful service life.

Other than that, I see many very useful benefits of going all electric. One could use a single motor, two motors and four motors, having a smaller motor drive each wheel separately. A natural four wheel drive, so to speak, with much less power loss than today, due to much more complex mechanics involved.

In some ways, an electric motor is the ultimate motor. No exhaust, no dangerous fuel involved, and it develepos maximum torque from rev No.1, i.e. its torque cruve is in fact a straight line.

The only thing I know I will miss is the sound of a healthy engine at 8,000 rpm and the growl of a decent V8. Heavenly!
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