I bought 10 of those for about $8/ea about a month ago. Of course, the price drops as soon as I buy it. Grumble. The problem these solved was getting constantly bothered by friends and customers[1] to buy for them cell phone batteries for their phones. I was buying them on eBay as a favor, but it has now become a major time burner. So, I passed out the hand crank chargers to anyone that asked, which hopefully has eliminated the problem. I haven't heard from anyone that actually used them.
What I think the world needs is a steam powered cell phone charger. Burns most anything, boils water, spins a turbine, provides charger power, and makes enough noise and smoke to clear the room. If starting a fire is socially unacceptable, a parabolic reflector to concentrate sunlight might work. It should work well if I can keep it from exploding. Something like this, but smaller: Or, maybe a Sterling cycle heat engine that uses the difference in temperature between air and hot coffee/tea to charge the cell phone while at Starbucks. This one looks cool:
[1] I have friends and I have customers. The only difference is that the customers pay me.
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Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Ummm... you're mixing up RF and solar powered (like I just did). The ACM paper was on ambient RF powered communications, not solar. No smoke or mirrors involved. Nanotech smoke and mirrors won't do anything useful for RF. For solar, the limiting factor is the size of the array. Power is limited to a maximum of 1 kw/meter^2 and maybe
15% solar cell efficiency. Moving or concentrating the light around doesn't produce any more power.
Someone did come up with a nanotech solar tracker, but I'm late for a free lunch and don't want to dig for it.
The system described in the article seems somewhat like a passive RFID tag. The tag rectifies the illuminating RF (usually 900 MHz). We're talking 1 watt of RF in the near field, not milliwatts at 1/2 mile. The rectifier also generates the 2nd harmonic of the illuminating RF. A data encoder on the tag modulates this 2nd harmonic by shorting the antenna, producing OOK (on off keying) modulation. Quite simple, but I don't see anything similar in the article or video.
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
On a sunny day (Fri, 03 Apr 2015 21:16:44 +0300) it happened snipped-for-privacy@downunder.com wrote in :
You may like this for info:
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I did the last scan half a year ago, something is there if you try several times... I don't care, I have cable and sat and the whole world for free on sat.
What I *think* happened (but I am in no way sure), is that when the switch to digital was made, the transmitters were in the big TV towers, and covered a large distance. Now it seems maybe those are on local small towers... and not MORE of those :-( And on top of that they seem beamed at large population areas (cities) or in the middle of those, leaving us in the country with whatsleft of the dBm or something. 'digitenne' is KPN. The KPN boss got a 460,000 Euro bonus, (half a million dollar for the year), politics and unions protested, now he returns the bonus, but he still got about a million base pay. If that is not making money by incompetence or Sell-Fish-Ness then what is.
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Mexican Slim tried to buy KPN, I really really hoped he would succeed, and make it into something customer friendly, but they (KPN) had a construct with preferential shares where they -could with just a few shares!!- prevent a hostile takeover.
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Must have pissed of Slim (he is second richest man in the world I think, after Billy The Gates). Seems the Netherlands wants to keep control of KPN at any cost.
So, KPN still has the best cellphone network. For now.
On a sunny day (Fri, 03 Apr 2015 12:02:43 -0700) it happened Jeff Liebermann wrote in :
nice
Those used to be toys in my youth..
That guy is good, wish I could do metal work that fast :-)
Why not use thermocouples in the camp fire?
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100 thermocouples in series gives you 5V.
You could also use a Peltier or 2, I tried heating one on one side, and a considerable voltage appeared (cannot remember how much though..) I have some DC power motors for model airplane, and some spare propeller. I could use that as wind generator (permanent magnet motors). For us electronic types there is power everywhere :-)
On a sunny day (Fri, 03 Apr 2015 12:12:56 -0700) it happened Jeff Liebermann wrote in :
No no! If you use micro mirrors (chips with micro mirrors) for the wavelengths that are in the range of those chips you can make a steerable antenna array. If you need a bigger wavelength just ad more chips. The micro mirrors will only reflect radiation back in the direction they point. Remember if you have a dish made of metal with holes, it still works if the holes are smaller than the wavelength.
I claim this invention that will make me Rich And Famous and soon every dumb^H^H^H^Hsmartphone will have this, starting with APPLE of course, as their own antenna designer was fired because you needed to hold it in a specific way. Apple can buy this Usenet patent from me. :-) At least they won't be able to patent it, as now it is prior art.
I once made a similar program for dumping the Transport Stream (TS) headers from Anysee DVB-T USB adapter.
That listing contained a reference to a DVB-H channel, but apparently none are active anymore. The DVB-H TS in Finland has been converted to DVB-T for regular TV service. So that DVB-H standard seems to dead.
There are two reasons for picking only a part of the channels in a single scan.
If due to flat fade, the whole weak TS is below the threshold while the tuner listens for a specific frequency, the scan will continue, if no signal is detected in a few hundred milliseconds. At rescan, the fade may have ended and the TS header can be read.
Individual Program Streams (PS) within the TS might not be active, some PS may start transmitting in the evening, so scanning during the day and you will miss that PS, even if other PS are found in that TS.
One of the reasons was the too positive early test results in UK with
16QAM 2k, which led to the assumption that you could drop the transmitter power to below -20 dB compared to the analog PEP. That would have saved a lot from the electric bill.
In reality, you may drop the Tx power with only about -10 dB to get the same coverage as analog TV.
Thanks to the Single Frequency Network (SFN) you can have low powered gap fillers on the same frequency, so a specific TV might receive the main station, alternatively the main station and a gap filler or only two gap fillers all on the same.
If the transmitters are at different direction as seen from the receiver, too much antenna directivity (gain) may actually hurt, since some signals from the gap filler(s) may be lost.
Wireless Devices Go Battery Free with New Communication Technique.
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Since I happen to live near a cell phone tower, I am curious to see how much power it would be feasible to harvest with an array of dipole antennae.
I am thinking siimple, like a row of a dozen or so brass brazing rods, stuck vertically into a block of perspex with their bottoms wired in series to ground via a load resistor.
Can anyone tell me, in determining the correct wavelength, how to compensate for the ''end effect", assuming a frequency of 1800MHz?
Also, how would I sdetermine a suitable value for the load resistor?
Is there any other configuration of dipoles, apart from the row described, that would be more effective?
Why hard to make? In the 2GHz region, the elements are about 3 inches long, and are easy to trim with dikes. A fixed gain receiver feeding a DC-coupled detector and an analogue meter will let you trim one up in an hour or two.
If you glue the directors to a wide rubber band, you can adjust all the spacings together. Once that's done, epoxy a dowel to the top and peel off the rubber, and you're done.
I was told of a steam powered floppy drive demonstrated for the local computer group in the late 1970s. I think it was a little model steam engine, small PM DC motor used as a generator, and a regular floppy drive - not sure if 8" or 5.25". The generator must have been good for at least a handful of watts.
"Where have you been hidin' out, lately, honey? You can't dress trashy 'till you spend a lot of money."
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It sells on their site for US$130. I've actually seen one of these on the shelf at a local store; I don't remember what it cost there. I have never tried to use one, though.
My light bill that is due in a couple of weeks is just a bit over US$77 for 511 kWh. So electricity costs me roughly 15.1 cents per kilowatt hour, delivered to the back wall of my house. The purchase price of the stove is worth approximately 860.5 kWh of utility electricity.
The stove claims to put out 2 W continuous, so I'd need to run it for roughly 430,200 hours, or 49 years, to generate that same amount of electricity.
I have seen online a prototype generator that had a DC PM motor, gear train, pulley. You hung it from the ceiling, filled a small cloth bag with rocks or dirt or whatever, ran a rope from the bag through the pulley, pulled the bag up to the ceiling, and then let the falling weight run the motor. It had a +5 V output for charging phones, and a white LED you could switch on for light.
On a sunny day (Sun, 5 Apr 2015 01:55:32 +0000 (UTC)) it happened snipped-for-privacy@att.net wrote in :
Nice.
and did some biking yesterday. Had not used it in a long time, no enjun, no *dangerous* fuel.. But anyways, it has a 'dynamo' say electrical generator, I could easily make a cellphone charger, it would be full after a trip. I know in WW2 people used bikes like that to make light.
Here are some more information and suggestions about wide-band harvesting rectenna:
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Feb 1, 2010 Ultralow Voltage Input Power Converters Support Energy Harvesting:
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Citat: "... Linear Technology's LTC3108, a highly integrated dc-dc converter, is intended for energy harvesting. It can harvest surplus energy from extremely low-input-voltage sources such as thermoelectric generators (TEGs), thermopiles, and small solar cells. ... This allows it to boost input voltages as low as 20 mV, to levels that high enough to provide multiple regulated output voltages for powering other circuits. ..." Schematic:
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Charging times:
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LTC3108:
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LTC3109 - Auto-Polarity "LTC3108" - for the people that can not get the polarity right :-) :
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Radio Frequency Energy Harvesting Project. Final Report for Science Faculty REF Fund. Supervisor: Dr JC Batchelor. Researcher: Dr PS Taylor:
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Quote: "... Radio frequency (RF) energy harvesting, also referred to as RF energy scavenging has been proposed and researched in the 1950s [1-2] using high power microwave sources ... [Please note the "awful" Yagi-Uda narrowbandedness in Fig. 5:] From the dimensions previously presented Fig. 5 shows the CST simulation results for the three band CCR antenna in terms of return loss. The results show the three clear resonances with a return loss of
20dB or better for all three bands in both polarisations. ... The zero bias Schottky diode detector has been previously used in RFEH [5 - 7] and other applications where no primary (DC) power is available. When combined with a simple antenna to form a receiver, it lacks the sensitivity of the superhetrodyne receiver, but offers the advantages of very low cost and zero power consumption. The single diode detector is shown in Figure 7. ..."
This planar antenna are much more broadbanded, and therefor much simpler to make. You then do not need expensive GHz equipment. You can scale it up from 25*25 mm to 107*107 mm (scaling factor: (3GHz/0.7GHz)*25mm ). The antenna will absorb up to about 11.5GHz/(3GHz/0.7GHz)=2.68 GHz efficiently.
Small Printed Ultrawideband Antenna With Reduced Ground Plane Effect:
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Quote: "... [Also see figure 2. Can be fine-meshed so it can be attached e.g. to a non-infrared-reflective window-glass.] The measured bandwidth for -10dB return loss covers the range of
2.95?11.6 GHz and has good agreement with simulations. The return loss response across the bandwidth features a multiple resonance operation. ..."
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Comparison of Antennas for Radio Frequency Energy Harvesting in 0.2- 2.4 GHz Range:
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17 January 2013, Comparative Study of Antenna Designs for RF Energy Harvesting:
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Quote: "... A typical rectenna consists of four main components: antenna, prerectification filter, rectifying circuit, and DC pass filter. Figure
1 shows a block diagram of a typical rectenna. ... As the primary function of a rectenna is to convert RF energy to DC power, the main design challenge is to obtain high conversion efficiency, and there are basically two approaches to achieve this goal. The first option is to collect the maximum power and deliver it to the rectifying diode, and the second one is to suppress the harmonics generated by the diode that reradiate from the antenna as the power lost. In order to increase the conversion efficiency by the first method, several broadband antennas, large antenna arrays, and circularly polarized antennas have been designed. The broadband antenna receives relatively high RF power from various sources, and antenna array increases incident power delivered to the diode for rectification. Antenna array is an effective means of increasing the receiving power but a tradeoff arises between the antenna size and the radiation gain. The circularly polarized antenna offers power reception with less polarization mismatch. To increase the efficiency by second method, LPF is placed between antenna and rectifying circuit or antenna with the property of harmonic rejection is designed. ..."
You can do band notching by designing "funny" slots in the monopole structure to minimize reradiation because of the diode do generate harmonics (because of the diode non-linearity) of the absorbed EM-signals:
A New Compact Ultra Wideband Printed Monopole Antenna with Reduced Ground Plane and Band Notch Characterization:
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It is even possible to restrict the wide-band monopole antenna to one conductor plane - via a coplanar waveguide:
A CPW-Fed Printed Monopole Ultra-Wideband Antenna with E-Shaped Notched Band Slot:
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An Investigation of Wideband Rectennas for Wireless Energy Harvesting:
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Quote: "...
This work is licensed under the Creative Commons Attribution International License (CC BY).
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... The results demonstrate that the maximum rectenna conversion efficiency is nearly 57% around 1.7 GHz and over 20% over the wideband of interest for the incident power density of 120 uW/cm2. It is noted that the impedance matching is one of the main factors affecting the rectenna energy conversion efficiency. [] This new wideband rectenna has great potential to harvest wireless energy in GSM/3G/4G and ISM 2.4 GHz bands. ..."
Quote: "... [pdf page 25] Power Summary: estimated by Friis equation
Outdoor (GSM/TV base station): 490 mW
Indoor (Cell Phone and WLAN): 202.5 mW
Received power at least 100 mW. ... [pdf page 29] Antenna b. Frequency
GSM/GPS/Wi-Fi Size
Max. Gain
> 2dB ... [pdf page 29. Energy harvesting on overdrive? :-) ] Future Work Construct an over-1mW energy harvesting system by combining multi-harvester.
Intelligent frequency-hopping RF energy harvesting system.
** Analyze trade-off between efficiency and wideband matching, targeting max. power transfer.
** Use power sensor to search for band with max. energy and dynamically tune the matching network.
Multi-sources energy harvesting power manager
** Adjust ff1 of DC-DC converter to change the loading for each ZHout of different harvesters ... [pdf page 37] Reference ..."
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My humble contribution:
How about several parallel non-overlapping band-pass filters, with their own zero-bias diodes and boost-converters - delivering to the same output (super)capacitor/energy-storage?
The filter cross-over frequencies has to be chosen at frequencies, where energy harvesting are not optimal.
Quote: "... [pdf page 25] Power Summary: estimated by Friis equation
Outdoor (GSM/TV base station): 490 mW
Indoor (Cell Phone and WLAN): 202.5 mW
Received power at least 100 mW. ... [pdf page 29] Antenna b. Frequency
GSM/GPS/Wi-Fi Size
Max. Gain
> 2dB ... [pdf page 29. Energy harvesting on overdrive? :-) ] Future Work Construct an over-1mW energy harvesting system by combining multi-harvester.
Intelligent frequency-hopping RF energy harvesting system.
** Analyze trade-off between efficiency and wideband matching, targeting max. power transfer.
** Use power sensor to search for band with max. energy and dynamically tune the matching network.
Multi-sources energy harvesting power manager
** Adjust ff1 of DC-DC converter to change the loading for each ZHout of different harvesters ... [pdf page 37] Reference ..."
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My humble contribution:
How about several parallel non-overlapping band-pass filters, with their own zero-bias diodes and boost-converters - delivering to the same output (super)capacitor/energy-storage?
The filter cross-over frequencies has to be chosen at frequencies, where energy harvesting are not optimal.
And the manager/CEO has a fine picture frame with the certification.
Somebody told me that it might also mean, that they do the same errors over and over again, because it now harder to make changes. The changes now has to be formally documented.
Beware the ISO 9000:
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Quote: "... ISO 9000 does not make any value judgements about a company's processes, it merely confirms that they are documented. A process could say to take a large foam clue bat and whack the customer and that would be perfectly fine to ISO 9000. ... At my present job, we have a Quality Leader/Kaizan Specialist on the division president's staff. Once the president dragged him down to our department because production was having difficulty with crimping connectors to cables (an actual quality problem!). The President told him that this was the perfect project for a Kaizan (a type of quality process meeting) and for him, the main Quality guy, to look into it. That was the last time we ever saw that guy. The threat of doing actual work scared the hell out of him. However, when we started having Quality training again, he was totally there, showing how good an organizer he was.
This type of person is worthless. Actually worse than worthless because they have to pay him. I believe that, if I were ever to become president of a company, I would interview every single employee and ask them one question: "How good are you at powerpoint? As soon as someone answered 'Excellent' or 'Highly Skilled', I'd immediately fire them, because, they are obviously not doing any work to help the company. ..."
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