No you wouldn't. You'd have 0 V between two chassis connected to the ground. Having one device with it's ground connected to the hot is rare. Having two such devices plugged in different outlets yet within arm's grasp of each other is fantasy.
Sadly such things can happen. Rare maybe, but why take the risk when it's avoidable?
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Dave Plowman dave@davenoise.co.uk London SW
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Is there a limit to the number of outlets on one circuit?
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Dave Plowman dave@davenoise.co.uk London SW
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Name one single case.
Why run power into your house at all if you are unwilling even to risk wiring problems that border on fantasy?
How would I be able to if it happened in the US?
Thought you still have some two pin appliances - so no safety earth and the plug can be reversed. Are you really saying you can't imagine a scenario where two faults resulted in the possibility of touching two phases? Of course if everything is protected by RCBOs etc it wouldn't much matter. But I got the impression some older installations weren't.
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Dave Plowman dave@davenoise.co.uk London SW
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I don't know, but likely. Many building codes require outlets every 'n' feet, not crossing a doorway. A friend had a vestibule between the house and garage:
--=====----- | | x x | |
--x--------
where x are doors, and === is a sliding door. To meet the code, he had 5 outlets in the space. There's no furniture but lots of places to plug in anything....
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Who knows? One Brit makes one claim, and another calls him a liar.
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I could tell you a thing or two about that as well. Balanced connections are VERY advisable especially with the rise in use of SMPSs with their associated ground leakage currents and the general increase in EMI pollution in the aether.
Graham
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grounding
call
offer.
installations...
drive.
I've done some research, and have been unable to find anything "definitive" about "grounding and its discontents".
I did ask the sous-manager of the Bellevue Magnolia, and was told that Magnolia did not require balanced cabling in home-theater systems -- it was the customer's choice. He didn't say how often they had problems with ground loops, buzzing, etc. The implication was that such problems were sufficiently rare that there was no need for Magnolia to insist on balanced lines.
I found the explanations given in this group about how unbalanced lines were inherently okay, and there was no reason one should ever have problems with ground loops, to be incomprehensible. (To me, anyway.)
I don't believe explanations until I actually understand them. For example, it took me 50 years (yes!!!) to understand why inductor saturation causes a loss of inductance. I'd never seen an explanation that went beyond "It is intuitively obvious, of course..."
Ditto for ground loops. I finally figured it out a few years ago. Briefly... Voltages are potential /differences/, not absolutes. When you connect an unbalanced output to an unbalanced input, the latter "sees" the voltage difference between the output line and ground of the "sending" device. If the AC grounds of the two devices are not at the same potential, the input will see this difference superimposed on the signal -- et viola! -- hum.
"It stands to reason" that, even if two devices are on the same power line, the farther apart they are, and the greater the difference in the current they draw, the greater the likelihood there will be a significant difference in the AC potentials of their chassis.
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I cannot find a cable isolation transformer suitable for digital-delivery systems. (Parts Express sells one, but says it isn't suitable for digital, which at least one buyer confirmed.) I put one together from two baluns, but haven't tested it yet.
Oddly, Comcast has not such device, free or even for sale. They say that customers either don't have problems, or don't complain about them.
Use an optical cable.
digital,
Oh? How? The system uses coax.
Does someone make an RF/optical, optical/RF converter?
Yes. google is your friend.
Err, either they're fitted with balanced connectors or they're not. To modify an unbalanced unit isn't a trivial matter. Involves either using expensive transformers at either end of the line or incorporating new electronics. You don't just buy a new cable. ;-)
It's really quite simple. With unbalanced you mustn't have a second connection to ground *anywhere*. Which means only one of the bits of equipment must have the mains ground connected - since with most the mains ground will be connected to the signal ground. Also applies to video and aerial connections.
In the UK pretty well all audio etc equipment sold is class II insulated so doesn't need a safety ground. But may have one for other reasons. Lift all of them apart from the one on the AV amp. You'll not then have a ground loop problem.
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Dave Plowman dave@davenoise.co.uk London SW
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Sure you do. Almost all "good" home-cinema (as well as middle-to-high-end audio) equipment has both balanced and unbalanced ins and outs. (My Parasound controller does. I use the unbalanced outputs to feed a Pioneer quadrascope.)
Total overkill. Balanced audio is only needed for very long runs or in very hostile environments - not found in the home. Are your aerial and video connections balanced?
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Dave Plowman dave@davenoise.co.uk London SW
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I've Googled, and as far as I can tell, there is no commercially available device that converts cable-TV RF signals to optical, then back again. What would be the point of such a device, when an isolation transformer would be much, much cheaper?
On the other hand, there are hundreds of products that convert TOSlink to coax and back again.
There is no reason. You can use a six hole Amidon core and make a
1:1 isolation transformer. Bytemark used to sell a lot of Amidon cores and beads at hamfests, but their website has been gutted. I can't find my Amidon Databook right now, but I'll see if I can locate it this weekend.You may find a suitable core in a junk two way 75 ohm TV splitter. The Amidon website is useless, but the style would be like their FB-61-5111-2.5, although type 64 core material would probably be better than type 61. You can open a diecast splitter by shoving a sharp awl or small screwdriver through the aluminum in one corner and peel the thin aluminum back away from the conductive epoxy. If you can't find one, I might still have some left from they 75 ohm return loss bridges I used to build. They are out in the shop, and its still raining around here, so it will be a day or two before I can check for you.
-- You can\'t have a sense of humor, if you have no sense!
available
What
be
Thank you for your suggestions and kind offer. I'd appreciate your looking.
When I was putting together this device *, I opened the balun with a F plug on one end and two screws (for the twinlead) on the other. ** The thought of "rolling my own" crossed my mind. The whole thing verges on the trivial, the "hard" part being firmly and stably attaching the F jack.
Two obvious questions...
** The other balun has a F jack on one end, twinlead with terminations on the other end.
They use 36 to 40 AWG solid well past 1 GHz
For best isolation I would use equal turns, a single wire for each side, passing through three holes., each.
The problem with most baluns is that they wind two 75 Ohm windings as a center tapped 300 Ohm transformer and feed the 75 Ohm to one winding, and take the 300 Ohm off both windings and have the center tap grounded, which provides no grounding. I used to buy fiber washers with a 3/8" I.D. and a 1/2" O.D. from General Cement to isolate one jack from a metal box. The other was connected to the box.
Keystone is carried by a lot of distributors. I don't know if I have any of the General Cement washers left. My last purchase was over
20 years ago.'Authorized National Catalog Distributors':
Allied Electronics 800-433-5700
or go to:
to find local wholesalers on a state by state basis.
I just looked at a damaged General Instruments four port tap with a broken 'F' connector. It was replaced in front of my house the other day because of an intermittent connection to a neighbor's house.. I see they are using a smaller core for the transformer Typical center tapped design, but tiny compared to the old 300 MHz version of the same tap. It appears to have three intact 1:1 wound cores. If you'll e-mail me with your street address, I'll pull a couple and mail them to you. Just separate the center tap, and use those leads as the pair of 'grounds'.
Use a couple short pieces of 'component lead' (AKA tinned steel wire, salvaged from a small resistor or capacitor) to connect them to the 'F' connectors.
If I can get to it, I'll send you a small coil of surplus component lead form the old Sprague capacitor factor in Orlando. I have a 20 pound spool, buried out in the shop somewhere.
-- You can't have a sense of humor, if you have no sense!
We've been through this before, and I'm not going to keep arguing. Most equipment these days has balanced connections. It's ridiculous not to spend a little more for balanced cables.
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