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Old 4th April 2013, 04:45 PM   #8781
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Yet again I prove I can not multitask . I am not even sure which one it was to be !!!! The boss phoned whilst doing this !
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Old 4th April 2013, 06:10 PM   #8782
mjona is offline mjona  New Zealand
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I can't help think that there is a little more baiting than debating going on between parties on this forum.

Michael J.
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Old 4th April 2013, 07:38 PM   #8783
dvv is offline dvv  Serbia
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Not really, just some good natured pulling of legs, or if you prefer, yanking of chains.

No need to be strictly formal, methinks. Nobody is here because they HAVE to be here.
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Per Aspera Ad Astra.
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Old 5th April 2013, 01:03 AM   #8784
mjona is offline mjona  New Zealand
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Quote:
Originally Posted by dvv View Post
Not really, just some good natured pulling of legs, or if you prefer, yanking of chains.

No need to be strictly formal, methinks. Nobody is here because they HAVE to be here.
In that context good natured pulling of legs is fine.

Michael J.
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Old 5th April 2013, 01:38 AM   #8785
bcarso is offline bcarso  United States
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Quote:
Originally Posted by mjona View Post
In that context good natured pulling of legs is fine.

Michael J.
"
Mr Barnard: Shut your festering gob you tit! Your type makes me puke! You vacuous toffee-nosed malodorous pervert!!

Man Look! I came in here for an argument.

Mr Barnard (calmly) Oh! I'm sorry, this is abuse.

Man Oh I see, that explains it.

Mr Barnard No, you want room 12A next door.

"

From Monty Python's Flying Circus, the argument clinic sketch
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Old 5th April 2013, 05:47 AM   #8786
mjona is offline mjona  New Zealand
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Quote:
Originally Posted by bcarso View Post
"
Mr Barnard: Shut your festering gob you tit! Your type makes me puke! You vacuous toffee-nosed malodorous pervert!!

Man Look! I came in here for an argument.

Mr Barnard (calmly) Oh! I'm sorry, this is abuse.

Man Oh I see, that explains it.

Mr Barnard No, you want room 12A next door.

"

From Monty Python's Flying Circus, the argument clinic sketch
Thanks Barney,

The Man
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Old 5th April 2013, 09:00 AM   #8787
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Quote:
Originally Posted by mjona View Post
I can't help think that there is a little more baiting than debating going on between parties on this forum.

Michael J.
Compared with school it's nothing . I should point out I worked on a farm and was very tough , it helped . One or two contributors are too serious and don't take criticism well . I say some daft things and get shot down in flames when I do . Sometimes that's when I learn most . I often know what I am saying is provocative , it's just good to go through the arguments one more time . For example and not me who said it . Voyager may not be responding to time in a way that we understand as it leaves the Solar System . I 99.9% don't think it worth repeating , 0.1% was enough that I wrote it . Do I beleive it ? 99.9 % no .
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Old 6th April 2013, 04:27 PM   #8788
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Click the image to open in full size.

This is something from work . LM317 . Zero interest in noise when doing the test and no requirement for it to be low . Just being certain no oscillation . The references voltages are about safety and not typical use ( we call 230 V 300 V when we can ) . The 317 will see no more than 32 V and 25 typcial . A double 317 was used as it is cheaper than a heat sink . 2 x 1R used in outputs and them connected as if a single regulator . No extra 10 uF to the adjust pin . Usual 0.1 + 1 uF as per application notes ( one set for two ) . Output voltage 10.2 V .

What I think we see here is statistical noise cancellation ? Interestingly not only lower but nicer . I have used multiple parallel op amps for noise reduction in the past . Perhaps this is why I liked it ? Anyway , thought it worth a share . I think I was told 66.5 mV ( divide by root 2 ) would be the least possible using this technique and would be 3 devices . Doubtless another reason might be the real one ? The current was 1 x 110 mA or 2 x 55 mA .
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Old 6th April 2013, 07:24 PM   #8789
bcarso is offline bcarso  United States
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Quote:
Originally Posted by nigel pearson View Post

What I think we see here is statistical noise cancellation ?
To be expected from paralleling, to be sure. In principle no limit to that, and with statistical independence of the internal references, will give a reduction factor of the square root of N (the number of devices). The effect on line rejection is another matter. There may be other interactive effects given the low resistances used for the combination, and one could be a little concerned about differences in the voltages of the internal references if the aim was an assured noise reduction. But as you point out this was not the aim of the paralleling, merely a reduction in device dissipation.
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Old 8th April 2013, 08:57 AM   #8790
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I reran the tests with a DC source . Not much to tell , a small reduction in noise . I should have said 0.665 mV as suggested limit . As said previously it is the shape of the noise that seemed to have changed ? I thought about output impedance . With 2 x 1 R sharing resistors the change should be for the worse . I thought about the lower current , if I get a chance I will rerun that . I might try a quad op amp , see where that goes . I especailly like them as the pin out is symmetrical , less chance for errors . LM 324 is nice and noisy , it might give more to look at . TLO74 and MC 33079 also . For once I see no reason to extend it to high cost op amps . The trends should be universal . 4 x MC 33079 should give less than 2 nV / root Hz in paralell . Using one at a gain of 62 at 500 uV ( max ) seemed to sound excellent . From what I understand the electrons would be scarce at that level . It beggars belief sharing the electrons out between 3 op amps in my case can work ! It sounded better especially in terms of warmth . Seeing these graphs I feel the warmth is explained . I have said that transistor sound is VAS + crossover distortion , perhaps add noise shape ? Tim de Paravacini was saying this years ago , I get the feeling the journalists somehow mildly lost the point . It is not the lower noise , it is the noise shape perhaps ? The way it was said is if we lower the noise as far as we can everything gets better ( especailly 1/f ) . I really doubt that , in fact I can see how noise could be useful in small amounts ( white ) . Shape of noise must matter . With a noisy source perhaps it will be clearer . One test will be using gain to equalize the noise levels between paralell devices and one device . I suspect LM 324 the best choice for easy to read graphs .

One thing I did find is LM317 delivers on it's promises and costs peanuts . Mine is an industrial application , I almost feel ashamed to ask it to do this mundane work .

Naim Audio used 5 transistor in paralell for MC pick ups , this is when I first saw it used . I suggested recently someone use a 6 transistor long tail pair for a conventional power amplifier . Doubly so now that I have seen the nature of the noise .
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