Never-connected clone?

[analog_sa]

Thanks to ALW for the Never Connected site.

What do you guys think of the principle and actual design? To me all is not quite clear but the main idea of using a switch to charge a cap for very short periods and only when the cap is not connected to the supplied circuit seems sound and not difficult to implement. Still, they're bound to be difficulties in the implementation.

What kind of switch to use? A MosFet? What about its own switching noise? The rest is also not so clear - swich to the rectified AC waveform or to another cap which is permanently charging? At what level of discharge to supply more 'juice'?

I wonder if any details of the patent application are known but it certainly will make a fun project.

[tiroth]

I'm not a SMPS guy. But to me it sounds like a direct mains SMPS (stage 1), except there is this other stage (stage 2) on the output that turns on and absorbs energy from the resovior (inductor/cap) ONLY when stage 1 is off.

This sounds good in theory but don't we end up with the usual SMPS issues? Even assuming that there are solutions to these, why not just use a normal SMPS supply from the start? Mr. Pass has already pointed out that these may derive their benefits from the low primary:secondary capacitance of the switching transformers.

Where is the benefit?

[Charles Hansen]

Hello -

If you are really interested in this, I would get a service manual for some of the recent high-end Panasonic DVD players. They used a technology called "Virtual Battery" that sounds to me exactly like "Never Connected" (at least from the superficial information available in the sales brochure). If they are the same (and I don't know if this is true) then Never Connected will have trouble getting a patent.

Best regards,
Charles Hansen

[Magura]

Sounds interesting Charles. The never connected caught my eye recently, i sure would be interested in implementing something like that....if not for anything else than to see what happens, since i frankly dont believe in it. It sounds like a SMPS with SMPS problems to me

Magura

[rherber1]

Had a look at the NC website and read Martin Colloms' review but nowhere could I find any real technical detail to make any real assessment. I take Martin's comments as being of little value since it can hardly be said that he is an unbiased reviewer. Martin has been known to "assist" in putting the best light on British products whether they are as good as he says they are or not. I dare say if this product had come out of any other country a local reviewer in that country would also have put it in the best light. Taking a review on the Accuphase PS-1200 Clean Power Supply http://www.audioasylum.com/audio/gen...ges/65099.html as an example from the USA as an example, we can see that this USA product has similar benefits for audio to that claimed for the NC technology.

I did note that the remarkable NC power supply - which is supposedly "never connected" directly to the mains ac supply - is priced at UKP175 - per rail that is. A nice little earner if you are silly enough to pay that much for a number of units for each item of audio equipment. It may well produce clean power suitable for audio equipment but I doubt that it will be significantly better than a properly designed low impedance PSU which uses more conventional techniques - and at a far lower cost to boot.

How can a power supply which is "never connected" actually work? It is a physical impossibility for it to produce power - clean though it might be - without actually having some physical connection to some supply source. When it comes to ac mains supplies you can only get that power by some direct means of conversion. It is either an isolation transformer if you want the best safety, or a mains SMPS. Whichever way you go there has to be some connection to the mains supply - all the time, otherwise there would be huge voltage fluctuations which could give rise to even worse problems. Even if you can store some energy momentarily during which time the mains supply connection is interrupted and therefore "not connected" during this interruption, I can see no advantage in doing so. After the interruption is over the magical electronic "black box" still has to reconnect to the ac supply at some stage, otherwise it will stop working. The fluctuations created by this sort of operation might also produce far worse effects for other equipment than that produced even by the ubiquitous SMPS. Even these potential "noise producers" can be quite efficient when power factor correction is included and proper shielding and filtering is used when powering small signal devices such as in audio components.

Methinks this is just another high priced money earner for the gullible audio enthusiasts who have little technical knowledge.

[Peter Daniel]

Originally posted by analog_sa
Thanks to ALW for the Never Connected site.

What do you guys think of the principle and actual design? To me all is not quite clear but the main idea of using a switch to charge a cap for very short periods and only when the cap is not connected to the supplied circuit seems sound and not difficult to implement. Still, they're bound to be difficulties in the implementation.

What kind of switch to use? A MosFet? What about its own switching noise? The rest is also not so clear - swich to the rectified AC waveform or to another cap which is permanently charging? At what level of discharge to supply more 'juice'?

I wonder if any details of the patent application are known but it certainly will make a fun project.

I would imagine they use two caps which are switched alternately. While one is connected to rectifying circuit, the other is connected to the supplied circuit and vice versa. If the frequency is high enough, the disruption in power supply in between switching is negligable as there are more caps downstream. It's pretty simple, or it seems to me

[rherber1]

Peter, I suspect that your guess as to how it works is as good as mine. Despite the fact that NC claims to be new technology, I doubt very much that it is. It seems to me to use a variation of conventional switch mode conversion, but in the end it is still a stop-start operation with all the attendant fallibilities of this type of operation.

If it is so good, and all that the makers claim for it, then I would expect it to snapped up and used by all the medical equipment manufacturers and radar equipment manufacturers where ultra-low noise powers supplies are vital.

[Peter Daniel]

It is actually like taking the power from a cap, which never runs out of stored energy. I don't know about radars and medical use, but it may be working pretty well in audio circuits.

[rherber1]

Yes, taking power from a capacitor is exactly what an SMPS does. The ac mains is first rectified and charges either one or two fairly large low esr caps to provide the low impedance source for the switcher. The idea is that the output load never really causes the stored voltage in the input reservoir caps to fluctuate to any degree. For audio equipment use an SMPS would have larger caps with lower esr and higher ripple current ratings.

[rherber1]

Personally, I would put more faith in using devices such as those available from http://www.soundlabsgroup.com.au/aud...com_qpower.htm

The cost is much lower and the benefits would be indistinguishable from that claimed for NC.