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Old 29th October 2012, 06:53 PM   #7521
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This is what Rotel recommend as an upgrade for the 965 clock . I think something a little better for the PSU would be wise .

XO
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Old 29th October 2012, 07:01 PM   #7522
bcarso is offline bcarso  United States
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Originally Posted by nigel pearson View Post
This is what Rotel recommend as an upgrade for the 965 clock . I think something a little better for the PSU would be wise .

XO
Yes, agree, and I see they are pushing voltage regulators as well. Even they look a trifle on the noisy side.
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Old 29th October 2012, 08:56 PM   #7523
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This looks so very easy to do . Perhaps it is good enough ?

http://www.diodes.com/_files/product...zetex/an51.pdf
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Old 29th October 2012, 09:31 PM   #7524
bcarso is offline bcarso  United States
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Quote:
Originally Posted by nigel pearson View Post
This looks so very easy to do . Perhaps it is good enough ?

http://www.diodes.com/_files/product...zetex/an51.pdf
Possibly. Noise is low, but there is no plot of output impedance with frequency, which, based on the single transistor circuit shown and the description of the shunt regulator, is important for the oscillator.
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Old 30th October 2012, 10:34 AM   #7525
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Zetex do mention low impedance and how it is compromised by even the shortest wiring . That suggests it was in the authors thoughts . It looks a very good risk .

To put it into perspective Rotel recommend upgrading from 78 series regulators to a larger number of LM317 . As the comparison here is with LM317 we might have without too much complexity a sort of bronze , silver and gold . The circuit looks simple enough to have a small PCB made ( yes please anyone ) . I think I remember Naim using 24 regulators in their middle range tuned up Philips CD player . If I understood correctly they selected LM317 and had an outlet for the rejects ( the majority , 90% ? ) . He was unwilling to say what the rejects were rejected for . Speed and noise perhaps ? I do know they said it was just looking for the best of devices , all theoretically were OK . My suspicion is as they tested everything they used it was no big deal if someone would buy the rejects to do it . If you think about it they buy lets say 1000 pieces at $100 . Then sell the rejects for $50 and end up with something they feel to be special at less than 50 cents each ( as they test everything anyway that is not a cost ) Recently they have made their own regulator which seems very complicated by comparison with the Zetex .

BTW . Even though 95% convinced as I was at the beginning I will try RC and perhaps LC alternatives to a crystal . It is not about being right or wrong . It is about being honest and saying I genuinely know . I would not do it with many things as the complexity and cost would make it stupid . In this case it is 5 minutes work to have something working . Do I expect it to be better ? No . Will I enjoy doing it ? Yes . Everyone told me idler driven turntables were a waste of time . Sadly for 60% of my life I didn't question it . They rumble so you don't want one , end of ...... Do they ? I have the world record on that at - 79dB weighted ( shared with Martina Schoener as it's both of us who created it ) . The irony is nothing different to a Garrard 401 except attention to detail . All parts of mine fit a 401 . As no one believed I had no books to read . My interest in general electronics came from building it's PSU which is no small part of the - 79 dB . I feel I could have taken 3 dB off of that figured it the motor had been properly in the feedback loop . There was an output transformer in the way . The next step a bespoke motor coil as did Thornes on the TD125 . The TD 125 wasn't feedback as such , it did at least have the lowest impedance . Also that type of motor steps so feedback will do very little to reduce vibration . The Garrard has a more elastic coupling of rotor to stator field . It's vibration is mostly rotational speed plus 100/ 120 Hz . There is chaotic vibration ( measured and considerable, jitter ? ) from the motor thrust bearing which I eliminated by an air bearing of sorts .

With Digital it is like a vegetarian eating meat for me . I find I can these days . CD ......?
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Old 30th October 2012, 11:44 AM   #7526
DF96 is offline DF96  England
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For feeding a crystal oscillator in a CD player the main criterion for a regulator chip would be noise, especially LF and subsonic noise. HF noise can be filtered away. Long-term DC stability does not matter.
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Old 30th October 2012, 01:21 PM   #7527
dvv is offline dvv  Serbia
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Nige, with everybody and their dog making electronic components these days, the need for incoming quality control is an absolute must for anyone half serious.

After stressing myself out with 317/337 woes, like exchanged pin places and similar ridiculous things, I just dropped them and went all discrete, all shunt. I still use them, but in non-critical places only, like providing power for LEDs and similar highly intellectual jobs.
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Old 30th October 2012, 01:33 PM   #7528
bcarso is offline bcarso  United States
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Originally Posted by dvv View Post
Nige, with everybody and their dog making electronic components these days, the need for incoming quality control is an absolute must for anyone half serious.

After stressing myself out with 317/337 woes, like exchanged pin places and similar ridiculous things, I just dropped them and went all discrete, all shunt. I still use them, but in non-critical places only, like providing power for LEDs and similar highly intellectual jobs.
My "favorite" not too long ago was discovering two different pinouts for the ubiquitous TL431 in SOT-23 and I think SO-8.

And no, it wasn't an audio application, rather a detector of automotive filler, typically used to conceal damage.
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Old 30th October 2012, 06:25 PM   #7529
benb is offline benb  United States
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A friend was putting together "introduction to soldering" LED flasher kits for Atlanta Mini Maker Faire and was having a problem with a batch of transistors, something like a 2n2222, he got from Digikey. They just weren't working in the circuit, whereas his previous ones did. I told him "check the pinout." He eventually looked at the datasheet for the exact part he ordered and found the pinout different from the previous transistors, but what I MEANT was for him to stick the thing in the transistor HFE connector/setting of his DMM using different pins for E B and C until it came up with a reasonable (50 to 200) value, in other words, check which pinout actually works as a transistor.
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Old 30th October 2012, 06:44 PM   #7530
dvv is offline dvv  Serbia
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Frankly, if I could, I'd ban such products. To me, this is a swindle, if the original has a certain pinout scheme, anyone producing replacements should HAVE to adhere to it no matter what, or you can't put the original's designation, because it is not a pin-for-pin replacement.

When it's a small signal TO-92 or some such, it's not too hard to get around it, but if it's a power device, then it's not nearly so easy.
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