Battery-free cellphone - Page 1
Forum section: electronics / general

author: Romain
author_rank: Regular Contributor
timestamp: July 07, 2017, 11:24:58 am
content: Who needs batteriser when you can have a battery-free cellphone??!http://www.sciencealert.com/this-battery-free-cellphone-works-by-harvesting-power-from-ambient-radio-signalsQuoteNote they are not claiming they can run a fullspec 8-cores smartphone, but just a simple txt (and call?) cellphone. I'd like to see the practicality of radio energy harvesting...Your thoughts?

author: Rerouter
author_rank: Super Contributor
timestamp: July 07, 2017, 11:33:02 am
content: If you where in a city center, possibly, with a super capacitor or similar to handle to voice modulation / demodulation, anywhere outside of 20K of city center, maybe 2 5 minute phone calls per day? maintaining the connection to the base station does pull a non trivial amount of power. and unless your near an area with a lot of transmitted power, there really isnt all that much floating around, as power decreases with distance squared.

author: tszaboo
author_rank: Super Contributor
timestamp: July 07, 2017, 02:12:45 pm
content: QuoteYou know, what this several meter reminds me? POTS.

author: NiHaoMike
author_rank: Super Contributor
timestamp: July 07, 2017, 02:51:21 pm
content: If they could get past the obsession of making everything as thin as possible, it would be trivial to put in a crank generator.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 07, 2017, 02:56:28 pm
content: Location is everything. Many decades ago a neighbor of a 50kW commercial radio station demonstrated lighting a 100 W bulb from an antenna. I don't know the details but I am sure that he was only a couple of wavelengths from the transmitter tower and was probably using an antenna many meters long. Where I am it takes a fairly good receiver to pick up anything. No one is going to run a telephone from captured power here.

author: Halcyon
author_rank: Unknown
timestamp: July 08, 2017, 03:56:06 am
content: "A custom base station receives the digital packets..."So in other words they would need to design their own network, on top of the what existing carriers already have, that has basically no hope of existing outside a very, very small defined footprint. If you're in the city or any other built-up area, chances are, you'd already have access to a power outlet or even an old-fashioned pay phone (which by law still exist in Australia). Not only that, this device is extremely insecure.A cheaper, more effective solution is just to carry a USB battery bank or a couple of dollars of loose change for the pay phone.

author: Ampera
author_rank: Super Contributor
timestamp: July 08, 2017, 04:12:12 am
content: Quote from: Halcyon on July 08, 2017, 03:56:06 amPay phone? What is this? I have never seen these.The only memory I have of using a pay phone is in like 2004-2005ish to call my parents because I was little and curious. I don't think I've used one since.

author: Halcyon
author_rank: Unknown
timestamp: July 08, 2017, 04:29:06 am
content: Quote from: TwoOfFive on July 08, 2017, 04:12:12 amYep, believe it or not, we actually still have fixed wire pay phones in Australia and it'smandated in legislation. This is to ensureall peoplein Australia have reasonable access to pay phone services on an equitable basis, regardless of where they live or conduct their business. According to ACMA (Australian Communications and Media Authority), there are just under 25,000 pay phones still in operation around Australia.This might seem a little crazy with the technology we have today, but don't forget, not everyone has a mobile phone and there are many areas in regional and rural Australia which simply doesn't have mobile phone coverage. If you have a look atTelstra's coverage map(which has the most expansive mobile coverage in the country), you'll see a lot of areas that aren't covered.The darker green areas denote 4/4.5G coverage and orange is 3G. There is a lot of space between towns where there is nothing (but some people live there). The light green areas are national parks, many of which have no coverage, but then again, people don't live there. A lot of people (including emergency services) right out there in the vast emptiness still rely on VHF and HF radios.Edit: Below is a photo I took recently, somewhere in rural New South Wales and even then, this was a main road which wasn't *that* far out of civilisation (sorry, I've had to significantly compress/resize it due to forum limitations).

author: Doc Daneeka
author_rank: Contributor
timestamp: July 09, 2017, 01:36:19 am
content: Quote from: Halcyon on July 08, 2017, 04:29:06 amThat argument seems a bit insane; these areas without mobile coverage certainly don't have payphones...

author: Halcyon
author_rank: Unknown
timestamp: July 09, 2017, 02:28:56 am
content: Quote from: Doc Daneeka on July 09, 2017, 01:36:19 amIt might seem a little antiquated to you and I, but you can't expect everyone to have a mobile telephone whether it be for coverage reasons or otherwise. Also, in rural areas, pay phones are still very common.

author: Brumby
author_rank: Unknown
timestamp: July 09, 2017, 04:40:05 am
content: Quote from: Doc Daneeka on July 09, 2017, 01:36:19 amREALLY?Do some homework before spouting off, please. It took me less than 30 seconds to find this example:Located at Opalton in Queensland - and according to the coverage map above is still more than 50km from 3G mobile coverage...

author: Ampera
author_rank: Super Contributor
timestamp: July 09, 2017, 04:46:16 am
content: Quote from: Halcyon on July 09, 2017, 02:28:56 amFor example, in the United States, for an unlimited plan from German Telecommunications, you gotta be ready to pay 100 USD a month for the service, not counting initial or financed costs of the phone you're using, or the price to get a SIM card installed. This is one of the most reasonable plans in the area, and it's specifically why my family doesn't use it. We don't need it, as we don't go anywhere, and when we do, we are doing something, and don't have the need for an internet connected device. We all have very cheap cellphone plans that are basically talk (and VERY basic texting) only. The US has probably the most unreasonable costs for mobile service in the world, although I would wager that Australia is even more bullshit, because almost everything is expensive there.

author: Brumby
author_rank: Unknown
timestamp: July 09, 2017, 04:52:12 am
content: Australia is a big flaming country. It is almost as big as the USA!We have a lot of sparsely populated area - and large distances of nothing.A solar powered phone booth with satellite connectivity is not exactly science fiction - and one could be placed anywhere.Certainly, with today's expectations, there is pressure on the telecoms to provide better mobile coverage and satellite connected booths may fade - but in this country, I can see them having a place for a very long time yet.

author: stj
author_rank: Super Contributor
timestamp: July 09, 2017, 02:50:17 pm
content: the u.k. still has all it's payfones.the owner (BT) isnt stupid, most if not all of them contain wifi hotspot equipment - saves leasing antenna space on other people's property!!

author: Brumby
author_rank: Unknown
timestamp: July 09, 2017, 04:54:23 pm
content: Quote from: stj on July 09, 2017, 02:50:17 pmLeveraging off existing, established sites that are already serviced.Very sensible idea.

author: Unknown
author_rank: Unknown
timestamp: July 09, 2017, 05:03:29 pm
content: Quote from: TwoOfFive on July 09, 2017, 04:46:16 amI don't agree with that. I just have some phones onTing, an MVNO. The connection fee is $6/mo with fairly cheap tiered usage based billing after that. It may not be as cheap as some Asian countries with new, dense cellular buildouts, but I wouldn't call the costs "unreasonable" unless you make them so (e.g. you demand an iPhone on Verizon with unlimited voice/data).

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 10, 2017, 08:12:22 pm
content: since the 80is Cordless Phones do not use Batterys.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 10, 2017, 09:39:23 pm
content: Quote from: Lord of nothing on July 10, 2017, 08:12:22 pmReally? I have replaced the batteries in mine. By opening the battery compartment door and dropping new ones in. 90s vintage and 2000s vintage.They are rechargeable NiMh. I suspect the cordless phones that are for sale now use LiPo or similar.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 10, 2017, 10:34:30 pm
content: QuoteSo there are not a Batterie.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: July 11, 2017, 03:34:12 am
content: Quote from: Lord of nothing on July 10, 2017, 10:34:30 pmLanguage problem? So what do you call those little cylinders that store energy chemically and deliver electric current? In the phones I have purchased a primary cell also works fine, but not as convenient as rechargeable which only requires replacement every decade or so.If you are doing some pun on the grammar it has not survived translation.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 11, 2017, 08:38:21 am
content: QuoteOnetime use -> BatteryMultiple use: Accumulator

author: Halcyon
author_rank: Unknown
timestamp: July 11, 2017, 08:41:25 am
content: Quote from: Lord of nothing on July 11, 2017, 08:38:21 amI've never heard anyone use the term "accumulator", but I get where you're going with it.In AUS, NZ, UK, US, Canada, they are collectively known as "batteries".

author: richard.cs
author_rank: Super Contributor
timestamp: July 11, 2017, 02:44:35 pm
content: In the UK accumulator is an obsolete term for the multiple use item (common up to perhaps the 1930s?), battery technically means a group of 2 or more cells of any chemistry, rechargeable or not, but in common usage refers to single cells as well.

author: strawberry
author_rank: Super Contributor
timestamp: July 12, 2017, 12:08:01 am
content: Am I right, Battery is series device that consist of small cylindrical cells.Battery as single cylindrical element is generalised slang came from Lead acid era..That's why Dura'cell'

author: Ampera
author_rank: Super Contributor
timestamp: July 12, 2017, 12:30:48 am
content: Many batteries are made out of multiple cells, but many are not. AFAIK, they are both called batteries in English speaking nations.I have never heard of the term accumulator. I have also never seen a cordless phone that uses single use cells.

author: tszaboo
author_rank: Super Contributor
timestamp: July 13, 2017, 08:05:51 pm
content: Quote from: Lord of nothing on July 11, 2017, 08:38:21 amI'm afraid not. The term accumulator is used in 3-4 countries, but it comes from the local language. In english, its one of the obscure rarely used words.Single use -> primary batteryRechargeable -> secondary batteryLithium battery without protection: cell. Technically, the Ni-MH AA and similar 'batteries' are cells.multiple cells connected together -> battery