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net-david 5th December 2003 02:10 PM

Never-Connected power supply
Does anyone have any information on how this power supply design works? I read something about it in either Stereophile or TAS, so I had a look at their web site: , and the sites of their dealers for upgrades to existing equipment; & .

The concept seems interesting, and the boards look simple enough. Is this something DIYers can duplicate?


richie00boy 5th December 2003 02:19 PM

I wonder if it works by rectifying the mains and smoothing it, then this is used to feed an oscillator to re-generate (an approximation of?) the 50Hz sine?

djk 6th December 2003 09:29 PM

Imagine you have a bridge running straight off the mains, no transformer.

You have a filter cap.

You have a load for the filter cap (audio amplifier).

You have a DPDT switch on the filter cap that can either connect it to the mains, or the load, but not at the same time.

The load is 'never connected' to the mains.

If the switch goes FUBAR you can get fried.

sam9 6th December 2003 09:54 PM

The name "Never Connected" may be good marketing but is otherwise a tad silly. In there more common type of power supply there is no wire that connects the DC rails of an audio device to the mains simply because there is a trandformer in between. In this sense, most audio equipment is "not connected". But so what? Dependeing on how you look at it either you are already "Never Connected" or so long as you are getting power to your equipment you are "unconditionally cxonnected".

Even a regenerator is connected is a significant sense - if the mains go out, the music stops.

If one is a fanatic about the suject, onr could in principle use the mains to charge a huge bank of batteries and then run an inverter from the batteries. Then there could be endles discussion about the appropriate exotic components to use in our diy inverters!

millwood 6th December 2003 11:06 PM

Sounds like a good product for the power cord advocates to try out, :)

djk 6th December 2003 11:29 PM

"simply because there is a trandformer in between"

Ever bought a large transformer? $$$

Ever lifted one? ###

These guys want to get rid of the transformer.

OTOH, the isolation provided by the transformer can keep you from being fried.

Kermit 6th December 2003 11:43 PM

For those interested, the article David is referring to is on page 29 in the December issue of stereophile.

net-david 6th December 2003 11:58 PM

Thanks Kermit. I was just going through the recent issues trying to find the reference.

Here is the interesting part:

"The Never-Connected approach takes advantage of the sometimes overlooked fact that the power supply actually takes up power from the mains over only a few degrees of the complete sinewave - the breif period in the cycle when the voltage on the secondary is higher than that on the supply rail, which is a necessary precondition for current to flow. NC's innovation is to isolate the equipment itself entirely from the wall during this part of the cycle by diverting the incoming current into a storage capacitor, then releasing it to the supply side once the AC current stops flowing."

sam9 7th December 2003 12:11 AM

Sounds a bit like the principle behind the power supply on my ancient Carver "Cube".

jcarr 7th December 2003 12:42 AM

Try this older thread, particularly the second page.

Mind you, it has _not_ been established for certain whether the type of circuit that we were discussing is similar in thinking to the Never Connected or not.

hth, jonathan carr

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