Is this for real?

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www.quirky.com/blog/post/2014/03/mind-your-watts-introducing-reter/
I can't believe this will work, since it's clamped around both H&N wires.
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On 3/5/2014 6:16 PM, Congoleum Breckenridge wrote:

The ammeter I've got requires a splitter, for that reason. I'm suspicious.
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On 03/05/2014 05:31 PM, Stormin Mormon wrote:

I'm stumped too. Clamp-on meters measure the field in /one/ wire.
If you put a clamp on meter over both wires since current in = current out the sum total would be zero.
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Maybe you've put your finger on it. The webpage says he "dreamt up Reter as an alternative to traditional clamp meters that fall short."

Maybe the "clamp" isn't over both wires. Maybe the sensor is to the side of both of them, much closer to one wire than to the other.

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Fields from a SINGLE long wire drop off as the inverse distance, 1/S.
Ah, but usually you have two wires, one with current + and the other with current -
If the wires are REALLY close together you can see how the plus and minus end up with almost zero field.
However, most wires have a bit of size to them, thus kind of close to them you get 1/S for the positive flow and -1/(S+dS), where dS is that smidgeon of extra distance. now you see, NOT zero field...
What you get here is 1/S - 1/(S+dS) = (S+dS-S)/(S^2+dS*S), for really small dS, throw it away and you get dS/S^2, thus everybody tells you how the field drops off as the inverse SQUARE of the distance.
Now, with judicious measurements made in a 'real' scenario; it is possible to find the current flow in the two wires just by examining the magentic field around the pair, albeit a bit tricky. For example, measuring close, and further, you can find the 'distance' between the wires and calibrate your measurement. In other words, measure current without knowing the exact structure of your wires. and determine the structure of the wires all at once. But, as I said, a bit tricky.
Most clamp on meters use an 'iron' core to distort and 'short' [as in concentrate] the field around whatever it is clamped onto. That type meter dtermines the TOTAL current flowing through whatever it's clamped onto, so if clamped on both AC wires, you get zero.
However, what I described is measuring the field WITHOUT distorting the field [well, not distorting too much]
As an extreme example of the effect of 'spatially' measuring fields to then determine current flow: My magnetic field measuring circuitry has extremely low noise floor. Using that circuitry I once designed a non-contact 'clamp on' multi-sensor system for measuring the independent current flows inside a 25 pair cable. ...for tapping any phone line you want. Each pair when 'active' is anywhere from 10-75mA and produces a noticeable field out to around 3 ft. If your noise floor is low enough.
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On 3/5/2014 3:31 PM, Stormin Mormon wrote:

The technology exists. But it depends on the physical arrangement of the wires in the cable. Standard flat two-wire cable, maybe. Twisted 3-wire cable of unknown internal dimensions, not so much. I wonder more about what powers the wifi.
In the real world, I expect the unknown cables will be problematic.
How many devices do you have that don't plug in and also have access to the power cable and it's only 2-wire? Water heater? nope Stove? nope Furnace/AC? nope And do I need an iphone to monitor it? KillAWatt is a better investment.
Also in the real world, accuracy isn't necessary. Energy savings is all about relative usage. Less is better.
You need two rules. 1) If you're not using it, unplug it. But you can't unplug devices where this might be useful. 2) Don't use it.
You don't need any measurements to do this. Shorter showers cost less. So take shorter showers.
Mike's metrology maxim... Never measure anything if the answer won't affect your future behavior. I know that a shower costs me about 13-cents. Am I gonna shower half as long to save 6.5-cents??? NO!
I have a device that monitors the utility meter and reports what it thinks. Before I go to bed, I often check to see if it reads 1Amp baseline usage. If it doesn't, I probably left the lights on in the garage.
I figger that in about 20 years, I'll have saved enough money to pay for the monitor...if I ignore the cost of 20 years worth of batteries.
So, my prediction for this device is that gadget lovers will buy it if it's cheap. If they specify accuracy, they're gonna get a lot of them back. If they really explain the benefits, people might realize they don't need one. It's a solution in search of a problem. Fortunes have been made on less...pet rock anybody???
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On 03/05/2014 07:04 PM, mike wrote:

placed just right it could work.
Forty years ago I never would have believed one could focus and image from a camera *after* it was taken...but I bought a Lytro which can do that. (After I had fun with it, I gave it to my daughter)
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<stuff snipped>

http://en.wikipedia.org/wiki/Lytro
I thought they had finally come up with something I could use to salvage the out-of-focus pictures in my collection. Not yet, although it is an interesting device.
I didn't believe anyone could take a helicopter to the summit of Everest because the air was too thin to provide sufficient lift but damn if they didn't! (and even go higher)
I also didn't believe that there were ever any SIX star generals. Turns out that's wrong, too. This getting old really sucks.
--
Bobby G.



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On 03/06/2014 02:19 PM, Robert Green wrote:

There is software that can do it, I don't know how well.
I just did a quick Google search and found this
http://www.focusmagic.com/
But there is a lot more.

I never even heard about that. I do admit to being a skeptic though regrading human-powered flight...and was proven wrong.

I thought when Omar Bradley retired that was the end of all five star Generals.
Please let me know about the six star variety I never heard of that one.
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Hmm, interesting. I'll have to give it a try. Thanks!

The internet taught me a lot about looking things up before I post and still I get nailed:
http://www.nationalgeographic.com/adventure/0509/whats_new/helicopter_everest.html
<<French pilot Didier Delsalle touches down on top of the world in a controversial Everest first.
Ever since Hillary and Norgay claimed first dibs to the summit of Everest in 1953, others have attempted their own "firsts" on the 29,035-foot (8,850-meter) peak (see "More Unusual Everest Firsts" below). But on May 14, 2005, test pilot Didier Delsalle, 48, of the French company Eurocopter made Everest and aviation history by landing his unmodified turbo engine AS350 B3 helicopter on the world's tallest mountaintop. His solo flight broke the unofficial record for highest helicopter landing, previously held by Nepalese Lt. Col. Madan Khatri Chhetri, who in 1996 rescued climbers Beck Weathers and Makulu Gau near Camp I at approximately 20,000 feet (6,096 meters). (The record for the highest helicopter flight is 40,820 feet (12,442 meters), set by Jean Boulet in 1972.) >>
FWIW, Boulet's turbojet copter flamed out at 40,820 and he autorotated down all the way. Talk about your Missouri boat rides! That must have been one hell of a descent. Unlike jet planes that can be "windmill started" in an emergency, a helicopter's turbo can't be restarted via diving.
It should also be pointed out that Everest is so windy on most days that a copter is fairly useless in rescue missions which frequently take place during immense storms. Squirrely handling at the best of times in the thin, windy air at that height. Impossible when the winds really whip up.

You're thinking five stars - they're as common as turnips compared to six stars, aka General of the Armies. Even stumped my retired Army wife with this one!
http://en.wikipedia.org/wiki/General_of_the_Armies

Only one man has been appointed General of the Armies in his lifetime, and one other posthumously:
I'll leave it unwritten in case people want to guess (or cheat to look smart!). (-:
--
Bobby G.



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On 3/5/2014 7:04 PM, mike wrote:

I put a power meter on my water heater at the end of 2008. The family was using $1.73 per day to heat water. Then my daughter went to college, now our hot water costs about $1.01. btw. I didn't save money with her in college :-)
Oh, I don't see how that can work with both wires running through it. Mikek
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On 3/5/2014 9:15 PM, amdx wrote:

I imagine there could be a way to do it.
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If the effective length of cable section being scanned by the detector arrays is limited to just a few millimetres, I doubt the usual rates of twist in a typical power cord would add more than a 1% error.
Even so, if such a sophisticated bunch of sensor arrays are being used, it seems very likely that the twist rate can be determined and this information used to cancel out any such 'error'.
It seems to be, as I said before, an awful lot of trouble just avoid seperating out the hot conductor to take electric field (voltage) and magnetic field (current) sample data to calculate a wattage reading.
However, if this tech is real and based on 'de-weaponised' 'Spook' technology that's been released into the private sector, then why not?
--
Regards, J B Good

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On 3/5/2014 6:15 PM, amdx wrote:

Up close and personal, near fields have more information that you can get from measuring at more than one point in space.
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repost a reply here....
Fields from a SINGLE long wire drop off as the inverse distance, 1/S. Ah, but usually you have two wires, one with current + and the other with current - If the wires are REALLY close together you can see how the plus and minus end up with almost zero field.
However, most wires have a bit of size to them, thus kind of close to them you get 1/S for the positive flow and -1/(S+dS), where dS is that smidgeon of extra distance. now you see, NOT zero field...
What you get here is 1/S - 1/(S+dS) = (S+dS-S)/(S^2+dS*S), for really small dS, throw it away and you get dS/S^2, thus everybody tells you how the field drops off as the inverse SQUARE of the distance.
Now, with judicious measurements made in a 'real' scenario; it is possible to find the current flow in the two wires just by examining the magentic field around the pair, albeit a bit tricky. For example, measuring close, and further, you can find the 'distance' between the wires and calibrate your measurement. In other words, measure current without knowing the exact structure of your wires. and determine the structure of the wires all at once. But, as I said, a bit tricky.
Most clamp on meters use an 'iron' core to distort and 'short' [as in concentrate] the field around whatever it is clamped onto. That type meter dtermines the TOTAL current flowing through whatever it's clamped onto, so if clamped on both AC wires, you get zero.
However, what I described is measuring the field WITHOUT distorting the field [well, not distorting too much]
As an extreme example of the effect of 'spatially' measuring fields to then determine current flow: My magnetic field measuring circuitry has extremely low noise floor. Using that circuitry I once designed a non-contact 'clamp on' multi-sensor system for measuring the independent current flows inside a 25 pair cable. ...for tapping any phone line you want. Each pair when 'active' is anywhere from 10-75mA and produces a noticeable field out to around 3 ft. If your noise floor is low enough.
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On Thu, 06 Mar 2014 05:21:37 -0700, RobertMacy

So, a bunch of electronically selectable and 'steerable magnetic detector arrays' plus a shitload of electronics then?
I suppose it might be do-able today (Hell! who'd have thought we'd have microprocessor chips with transistor counts measured in hundreds of millions (last figure I saw was 135 Million nearly a decade ago).
Seems to be an incredibly 'over-engeered' solution' just to save the need to isolate the conductors to take a current measurement though.
--
Regards, J B Good

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On Thursday, March 6, 2014 7:38:31 AM UTC-5, Johny B Good wrote:

The part that makes it hard to believe is that this is apparently some little company that doesn't even have a real product to sell yet. It looks like a small, cheap device targeted at consumers. They don't say anything about any new technology, patents, or how they do it. You would think that if this were possible to do with any reasonable accuracy and cost all the pros in the field, eg Fluke would have been out with it long ago. A simple clamp on that you could put around any power cord/cable like that would be an instant seller.
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On Thu, 06 Mar 2014 05:38:31 -0700, Johny B Good

My guess at material cost for using 'available' components, around $200, and DSP processing at much less than $800
Well it's for people who want to do something and not be noticed doing it. Especially undetectably tapping a single phone line from 1 to 3 feet away, through a wall for example, then use a short range 'retransmit' to get it out without tracking the contact back to yourself. package something like that in a wad of tar, so it looks innocuous, like tar dripped from the ceiling onto the cabling, etc.
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On Thursday, March 6, 2014 8:43:20 AM UTC-5, Robert Macy wrote:

Except that from the link that's clearly not the market being targeted and the price point obviously isn't $3K either
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On Thu, 06 Mar 2014 07:33:32 -0700, snipped-for-privacy@optonline.net

Interesting how you went from one shot cost of $1000 to market at $3k. Maybe I should have posted the estimated costs for volume of 100 to 1000
Either way, I wa responding to the idea that intelligently using the field mapping around a cable was exhorbitantly expensive. Back to a single pair current measurement...
could be cost as low as $2 plus housing in 100's quantity.
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