Ukrainian startup: We’ve solved long-range wireless charging - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: December 24, 2015, 12:02:26 am
content: "Buffer Battery" is all you need to know about this one. I stopped reading after that.http://arstechnica.com/information-technology/2015/12/ukrainian-startup-xe-claims-to-have-solved-wireless-charging/

author: georges80
author_rank: Frequent Contributor
timestamp: December 24, 2015, 12:09:22 am
content: The clincher is the statement:"That's the time needed for the buffer battery to build up a head of steam"Excellent, we're back to steam powercheers,george.

author: Howardlong
author_rank: Super Contributor
timestamp: December 24, 2015, 12:37:33 am
content: Even if 100% efficient, I'd like to see how he'd get the 5W claimed through any type approval/certification.That, among a plethora of other holes, it's difficult to know where to start.What's disappointing is that AT's journo wasn't up to the job of understanding much about how wrong it is.

author: taemun
author_rank: Regular Contributor
timestamp: December 24, 2015, 02:16:22 am
content: Stumbled over this:http://arstechnica.com/information-technology/2015/12/ukrainian-startup-xe-claims-to-have-solved-wireless-charging/Ukrainian startup, <100MHz transmitter with <5W power output. Apparently they're guiding all of that energy to the receiver, instead of being dispersed evenly around the room.Their website:http://technovator.co/Thoughts?

author: Brumby
author_rank: Unknown
timestamp: December 24, 2015, 02:38:36 am
content: I would think this technically feasible with some sort of beaming technology and a practical way of aiming it, but one must wonder about the biological effects.Walking past a transmitting 5W omnidirectional CB antenna is one thing, but walking through a focussed beam is a little more concerning - especially when this is likely to be transmitting for long periods. (One would hope the system is smart enough to only transmit high power when there is a device to charge present.)I would be interested to see the FCC examine it.

author: ataradov
author_rank: Super Contributor
timestamp: December 24, 2015, 02:40:30 am
content: How is it Ukrainian, if they only have offices in the US and Polland?

author: Brumby
author_rank: Unknown
timestamp: December 24, 2015, 03:08:04 am
content: QuoteIdentical? Hardly. If they wanted to compare it ti Tesla's wirelesspowertransmissions then I'd agree - but they are comparing it tosignaltransmissions. The reference to mobile connections immediately adds another question mark when it comes to the next claim:QuoteAs far as I am aware, the jury is still out on the biological effects of EM radiation.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 24, 2015, 03:34:52 am
content: Quote from: Brumby on December 24, 2015, 03:08:04 amWell, that's the thing about a legal (jury trial) truth versus a scientific (statistically highly confident) truth, they are two different things. Me? I'd much rather have the former, when at all possible. (It's not always possible, which is why we still have much of the judicial system as we know it.) But if you prefer opinion, that's up to you...Aside from low statistical significance studies, andanecdotal reports*, the only proven effects of EM are 1. bulk heating (any frequency, but mainly >10MHz), and 2. molecular excitation and ionization (only for E&M > 1eV or so, in other words, anything you can see or higher). It would seem biological beings areway the fuck more robustthan average electronics, over most of the EM spectrum we have available.*He sneered, knowing that the plural of anecdote is anecdotes, not data.Anyway, the topical point remains; even if energy can be beamed safely around people (which is honestly not hard, and may be accidentally too pleasant, e.g., imagine UHF space heaters..), there's simply no way it won't interfere with, and utterly destroy, so much common electronics. Interference is the bottom line the FCC and IEC and others are concerned with, so it just can't happen.Tim

author: wbeaty
author_rank: Contributor
timestamp: December 24, 2015, 04:48:17 am
content: When they mention "crystal radio," it probably means they're doing the same as MIT's "wi-tricity" project. It's that same odd nearfield-resonance effect, high-Q antennas with large EA effective aperture.In theory it's possible to transfer *unlimited* energy in the nearfield zone. Just use a tuned-primary tuned-secondary transformer with infinite "Q." Basically that's how crystal radios can drive earphones without being connected to a thousand-foot vertical longwire antenna. The higher the resonator Q, the stronger the oscillating flux surrounding the local receiver, and the larger is the effective area of your antenna. This is true even when the physical antenna size is << wavelength. That's for antennas, but the same physics applies to transformers. We can make air-core RF transformers the same coupling as heavy iron cores, simply by using a pair of tuned circuits. With sufficiently high Q, a resonant transformer will behave like a direct wire connection, even with large space between primary and secondary (up to a 1/4-lambda distance.)Modern products using this effect are the passive "amplifiers" for AM radio: the Select-A-tenna and the Terk Advantage products. They're just physically large, high-Q tank circuits tuned to the same freq as your AM radio, and placed nearby. They only amplify your antenna's EA diameter, and so increase the total microwatts being absorbed from passing EM waves. They seem like magic because there are no connections: your AM receiver lies within the strong fields of the separate tank circuit, giving unnoticed transformer coupling.Real world limitations: it's better to have larger diameter antenna coil (or higher operating frequency,) and unless we're using room-temperature superconductors, a physically heavy tank-circuit gives higher Q. Just use many KG of ferrite, many KG of copper litz wire. That way your small antenna-glob will absorb EM as if it was a very long halfwave dipole. You can use it to charge a phone at high wattage over impressive distance. The challenge is to adjust parameters for acceptable materials price and physical receiver size. BRAINSTORM: several-pound pancake-coil antenna, perhaps aluminum foil-tape rather than copper wire, then make it bowl-shaped and convince the user to wear it on their head like a hat! (Aluminum tape-wound coil equals, ahem, tinfoil helmet. But it would work! It really would!!!)

author: SeanB
author_rank: Super Contributor
timestamp: December 24, 2015, 05:27:50 am
content: Funny enough when I took apart a tag detector the coils were wound with aluminium foil, around a half kilo per coil. Would have been 10kg of copper foil if they had gone that route, and the resonating capacitors were 3-5uF polyester foil units. That thing would make any metal within 5m whistle when it was in use, and we had to move the monitor 5m away so the CRT did not sit there all day and wave at you.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 24, 2015, 05:28:19 am
content: Quote from: Brumby on December 24, 2015, 02:38:36 am5 watts is still only 5watts ---gain antennas don't "focus" the transmitted signal,they just make it look like a transmitter of higher power into an isotropic antenna.Feed that 5watts into a resistor,hold the resistor--it will get warm,maybe hot,depending on the resistor ratings.That is all the power there can ever be.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 24, 2015, 05:42:49 am
content: All that said,as soon as the Bank in Nigeria comes through with my $35,000,000 for helping the Prince free up his funds,I'll immediately invest $1,000,000 in this product.

author: Brumby
author_rank: Unknown
timestamp: December 24, 2015, 06:18:33 am
content: Quote from: vk6zgo on December 24, 2015, 05:28:19 amSorry if I used the wrong word - but any antenna with directional characteristics is going to have more W/m2in one direction than another. However, I may have incorrectly assumed that the power emitter of this unit may use a directional antenna.QuoteThis is a macro effect. It does not preclude other things going on which are not so obvious.

author: Brumby
author_rank: Unknown
timestamp: December 24, 2015, 06:31:11 am
content: Anyway, while the concept is nothing new, there remains the question as to whether it is a product that will clear all obstacles and actually make it to market.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 24, 2015, 06:44:09 am
content: Quote from: wbeaty on December 24, 2015, 04:48:17 amNot mentioned, but perhaps implied: bandwidth is inverse with Q. So an "infinite Q" crystal receiver would be really useless, as you'd only ever hear a low grumble! (But it would be okay for CW, as long as the filtered signal is mixed with a BFO before detection. And as long as your tuning is super accurate, and never drifts. Which, well...)On a related subject: I've played with the spurs from a crystal filter before; some of them are quite narrow indeed, in the 100s of Hz. Tapping on the RF signal generator (which, since it uses an air variable capacitor, is quite AM and FM sensitive to vibration) results in a thumping sound, akin to the sound of tapping on, well, a metal chassis (who would've thought!), but as heard through a hundred feet of steel pipe, or something like that. Except it's not waves trapped in a pipe, but vibrations in a tiny crystal, vibrations that have a time constant in the tens of milliseconds! Cool stuff.Also, the Q sets the impedance ratio, of how the tank's impedance (characteristic Zo = sqrt(L/C)) matches against the source/load impedance. For reasonable values of L and C, at a very high Q, neither series nor parallel impedances are very inviting! (The same problem is encountered in induction heating, where the tank Q is modest, but the impedance is low to begin with. Direct (parallel) drive is typically an option, but difficult because it has to be constant-current, which makes the inverter more expensive. Series is much easier to use, but necessitates a very low drive impedance, typically tens of milliohms. But this is handled easily with a large ratio transformer and single-turn secondary, so it's not as bad as it sounds.)QuoteActually, superconductivity is a finicky thing. It's certainly not unlimited in frequency -- the Cooper pairs are bonded with ~meV of energy, so it stands to reason that photons in that range (THz+) will decouple them, and the solid ceases to look like a superconductor near that frequency, or its superconductivity gets destroyed*.*Actually an effect, as far as I know: superconductors can be "switched" by saturating them with such radiation, which effectively heats the electrons I suppose. But because the temperature of the solid is mostly phonon energy, it doesn't heat up much. You could think of it as, there are two temperatures at work (the material and the electrons), and you're only heating one (transiently).In fact, Type II superconductors exhibit hysteresis loss (the conductive equivalent of ferroelectricity?), which is evident in most videos using them: flux pinning. It's a DC hysteresis effect, where some flux gets trapped in the bulk, rather than being fully excluded (Meissner effect). Any time you have varying flux, there is some chance that it gets pinned and unpinned, resulting in losses. Hence: finite Q for any frequency from near-DC to cutoff.Even Type I superconductors are known to have losses, though it's my understanding, no one really knows how or why. The typical Q factor of niobium resonators (used in LINAC beamlines at LHe temperatures) is 10^9 when unpolished, rising to 3 x 10^9 or so when polished (but not too well polished, or something; it's picky and empirical, as I recall).Still, 10^9 is no Q factor to laugh at, what with quartz crystals topping out in the 10^5 range!For present day, room temperature materials, at low VHF frequencies, I don't think much more than 2000 is remotely reasonable. And that's due to losses alone; with source and load impedances included, picked for modest efficiency, that pulls down to maybe 200-500.QuoteYeah, using low loss ferrite (e.g., #61?), and arranged so that it produces a maximum of external field, of course (e.g., loopstick).NiZn ferrite is noticeably more expensive than MnZn, so what with the needing kg of it... and kg of litz... yeah.QuoteThe legendary Bill Beaty, ladies and gentsQuote from: SeanB on December 24, 2015, 05:27:50 amAre you sure they were polyester? (...How would you know?)Polyester is all but useless for any amount of power:and the Q isn't great to begin with, so I wouldn't think they would get very far. (Fair note: those were CDE's DME series, which are one of the smallest volume-per-CV caps you can find. They should be expected to be lossier than usual. The runaway characteristic of PE isn't so helpful, though -- which is one thing PP will get you, stable operation even when running hot. Right up until the case splits and the guts ooze out, and I'm not even kidding about that, I've done that too!)Polypropylene is available in dipped packages, so you can't really tell by looking.Tim

author: SeanB
author_rank: Super Contributor
timestamp: December 24, 2015, 02:29:33 pm
content: Seeing as it only was around 30W of power, and had a class D output stage ( and 2kg ferrite core chokes) it is not exactly high power, just enough to read shop tags.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 25, 2015, 03:25:16 am
content: Merry Xmas Mojo-Chan!!