Questions tagged [cellphone]

Questions regarding cellphones, or cellular devices. Please note that repair questions are often closed for failing to follow the Scope of the Site as described in the FAQ.

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1answer
40 views

How to solder the 4-pin battery connector back to phone's motherboard?

One wickedly hot day the battery of my old Nexus 4 swelled up. I use that phone as Android development platform, so most of the time it was plugged into the computer for USB debugging. It's been ...
0
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2answers
40 views

Is there any physical limitation to cell carries sharing the same frequency?

Currently in the U.S. certain companies are granted leases on certain frequencies for cell phone communication. I was discussing with a friend how this allows a company with a lower frequency to get a ...
1
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1answer
86 views

Why does my phone pull less current from power bank when the screen is on? [closed]

While charging my phone (a Samsung Galaxy S5) with a power bank that displays the power output with 0.1 W resolution, I turned the screen on. To my surprise, the power pulled by the phone went from 7....
3
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1answer
151 views

Why can't we divide the electromagnetic spectrum into arbitrarily many radio frequency bands?

I understand there is concern over the limited amount of wireless spectrum available for allocation but am somewhat confused as to why. Couldn't we just divide the electromagnetic spectrum into as ...
0
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1answer
32 views

Camera LED in phones - PWM or analog current controlled?

The LED illuminator/flash that is used on cellphones with cameras is also controlled by flashlight apps. Is the light level controlled by pulse width modulation or is it analog current controlled? In ...
3
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1answer
87 views

How does a cellular network deal with a duplicate SIM? [closed]

I was pointed here from WorldBuilding. Say I had a cellphone, let's call it cellphone A, and made a perfect copy of it - SIM card and all - and let's call this one cellphone B. If I were to call ...
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2answers
87 views

Identify that connector - Is it reusable?

I have an Asus Zenfone AR which has had the screen replaced 3 times. Last time I replaced it myself, Asus the first 2 times. Screen replacement went fine but once together I discovered up volume ...
0
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2answers
77 views

Security/safety circuits in removable cell phone batteries?

It seems like the aftermarket phone battery is so flooded with terrible counterfeits it can't be too hard to trick a phone into thinking a battery is genuine. I'd really like to learn how to use an ...
0
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1answer
78 views

Google Pixel XL; Anyone know what this middle piece is called and what it does? [closed]

Does anyone know what this middle piece is called in the Google Pixel XL? Here is the image (I've underlined in blue): I noticed that it emits infrared light. I think its a proximity sensor but I ...
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0answers
58 views

GSM antenna connection from the phone does not make sense

I recently came across a phone (Samsung Galaxy Grand Prime SM-G530f) with trouble getting any network signal, I did some troubleshooting and ended up finding out that one of the pin(the GSM pin) to ...
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1answer
66 views

Is it possible to generate user-defined signal using an android phone?

Is it possible to generate an electronic wave signal using an android phone? (Theorically) For example by customizing the firmware can I produce some signals like \$ f(t)=2 \sin 3.2×10^9t+3\cos 5×10^...
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1answer
125 views

“Leeching” clock information from cell towers

I understand that cell base stations transmit very accurate time signals among other things. Do you need a SIM card and an account to receive this information, or is it something you can "leech" with ...
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1answer
158 views

How can a phone transmit the signal back to tower? [closed]

If cellphones have such a low power transmitter (around 200mW for LTE) and also doesn't have directionality then how can they talk back to the tower even though they are so powerful and built ...
0
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1answer
80 views

How can I power a USB cord from a 12v 2a power supply?

I'm new to the forums and have a problem I cannot find an answer to. I am making a lamp with LED strips inside powered by a 12v 2a power supply. I want to also power a USB cord with this power ...
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1answer
126 views

How does cellphone idle time work?

Imagine a basic cell phone which operates in only 2G network and able to provide voice call & SMS service. Does this cell phone transmit any data to BTS in idle time (that is when the cell phone ...
0
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2answers
152 views

What's the hardware and software detect mechanism of the cellphone Micro USB devices attached and detached?

What's the hardware and software detect mechanism of the Android cellphone Micro USB devices attached and detached? simulate this circuit – Schematic created using CircuitLab Hardware ...
2
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1answer
60 views

Does Quick Charge have an effect on battery lifespan?

When charging my phone (a Samsung Galaxy Note 4 using a 3,220mAh lithium-ion battery) I have the option of charging it with with a standard charger or a Quick Charge 3.0 charger. Quick Charge is a: ...
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1answer
40 views

Direct Phone Charge from Solar Cells via USB

I have a 19V 0.7A series of solar cells I'd like to connect to a standard 5V USB breakout PCB for phone charging. Do I need to worry about causing damage to the phone or battery without a regulator? ...
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1answer
80 views

Fast charging ports under the hood - technical details behind the standards? [closed]

There are a few things I noticed and examined for two different fast charging standards: MediaTek PumpExpress works without any data communications with the charger. Output 2 from my USB multimeter ...
21
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6answers
2k views

What drives the advancement towards ever faster cellular network speeds? [closed]

I've always accepted that technology advances. Being born in the 90s, everything just becomes faster, smaller, cheaper and generally better if you wait a few years. This was most obvious with consumer ...
0
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1answer
151 views

Can a 3.2V, 400mAh battery charge a smartphone?

I have a solar panel that slowly charges this battery and I am thinking of trying to make a cell phone charger out of it. I know it won't be fast, but will it be able to charge a phone?
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3answers
125 views

What technology is used for authorities to send emergency alerts to mobile phone users? [closed]

Do modern-day protocols that our mobile phones run on eg. CDMA/GSM, 3G or 4G have a emergency break-in/broadcast protocol for authorities to issue warnings to the public? In the recent case in Hawaii ...
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1answer
70 views

Is it possible to move an internal SD card from a Samsung Galaxy S3 into another phone (Galaxy S2) to retrieve the information from the card? [closed]

Is it possible to move an internal SD card from a Samsung Galaxy S3 into another phone (Galaxy S2) to retrieve the information from the card, or is there any other way to access the information from ...
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2answers
124 views

Multiple induction coils in series (phone charging)

I'm doing a DIY project of sorts, and I'm trying to create an array of about sixteen coils in series in a sort of square. The goal of this is to make a larger charging surface than just a small pad, ...
1
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1answer
677 views

How hot does a lithium-ion phone battery have to be before it explodes?

I have an LG G4, model LG-H810 (serial indicates it's one of the shoddy-soldering ones) and it gets extremely hot during light gaming or while watching videos. It's not too uncommon for me to pick it ...
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2answers
2k views

Identify which bus, mobile phone batteries use?

Mobile phone battery bus are usually 3 pin or 4 pin which are usually 2 wire buses (I2C) or a similar type of serial interface for a 1 wire bus. Does anyone know of a method for checking which bus ...
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1answer
116 views

How to remove folded battery from phone without starting a fire?

I was trying to replace the battery in my phone, but since it was very well glued to the phone, I accidentally folded it in half. This immediately caused some dark brown smoke to come out from it, so ...
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2answers
55 views

How are higher dimensional sphere packings used in signal transmission?

How are higher dimensional sphere packings (HDSPs) related to the error-correcting codes used by cell phones, space probes and the Internet for signal communication through noisy channels? HDSPs ...
0
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3answers
46 views

Velocity limit of UMTS and (or) CDMA2000

If the client is moving relative to the base station, the Doppler shift would compress or extend the packet. If the effect is strong enough, the PN generator in the receiver will eventually get out of ...
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votes
1answer
56 views

Ghost screen in the background…like water mark in my cell phone screen [closed]

I'm using Moto G4 plus bought during Feb'17.I have been noting this problem for a few weeks.If I stay long in a screen for eg. a chess game, the screen stays on all the following screens in the ...
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votes
1answer
65 views

Why sometimes I have voice but no data on a GSM network? [closed]

From what I understand, both voice and data are using the same antenna (At least 3G). Sometimes in a remote area, I have plenty of signal but no data service. Is it possible some cell towers don't ...
0
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1answer
143 views

What is a phone unlock box? [closed]

I have read about a phone unlock boxes (JAF, Phoenix, etc). What are they exactly? Some serial adapters? JTAG adapters? What is their role and what makes them so expensive?
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2answers
87 views

Powering multiple cellphones with a DC power supply

I have about 100 cheap cell phones that need to be on 24 hours a day. Unfortunately (likely due to the cheap nature of these phones) the batteries end up bloating after a couple months of being ...
1
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1answer
389 views

Polar pattern of typical speakers and microphones found in smartphones

I'm interested in knowing how is the directivity of the typical microphones and loudspeakers found in smartphones and tablets affected as they operate in the near ultrasound region (18-21 kHz). Near ...
0
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0answers
77 views

Can cell phones be reprogrammed for peer-to-peer connectivity avoiding carrier base stations to create a free meshed network? [duplicate]

In light of recent events concerning the freedom of internet, thoughts are going in the direction of breaking free from the control of wired internet service providers. One widely discussed option is ...
1
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2answers
694 views

Can a person suffer mild electrocution if he answers a charging phone with wet hands or sweaty palms? [closed]

This texas girl got electrocuted and died while using her cellphone in the bathtub. Can a person with wet hands or sweaty palms face mild electrocution if he answers the phone while it is being ...
0
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1answer
162 views

Phone charging problem with vehicle power adapter [closed]

Let's compare 2 situations: My smartphone is totally discharged. I plug a standard phone charger (standard 5V adapter, with micro-USB, wall adapter), then the battery increases of, say, 1% percent ...
4
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4answers
325 views

Why modern cellphones do not have an externally visible antenna?

Old phones had either a fixed antenna inside a housing which was externally visible, or a retractable antenna, which was visible when used. I'm assuming this was needed to obtain a certain total ...
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1answer
70 views

Can cellphone magnetic holders affect the CPU?

My concern is mostly related to the various IC components such as CPU. I know that one of the problems of miniaturization is that electons jump to neighbouring lanes. Given how tight things are in an ...
0
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1answer
74 views

Could sliding down a slide damage my camera? [closed]

Specifically one of those plastic spiral slides - I was at the playground with my children yesterday and when we went down the slide there was enough static generated to stick our hair on end. Of ...
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votes
1answer
73 views

Damage a phone from intermittent charging? [closed]

Is it possible to damage a phone by charging it with an intermittent power source? For example, by using piezoelectric transducers in the soles of your shoes. Assuming they're wired to a 5V ...
1
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1answer
1k views

Is it safe to use RFID in a phone case

I looked into this and found only vague indications that it should be no problem, but nothing specific enough to feel safe. Based on reading this question and its answers and comments it seems like ...
0
votes
1answer
89 views

Using “Video 90” spray to clean up a cell phone motherboard

Can I use Video 90 Spray with electronic motherboards, like smartphones? My cell phone was dropped in water while the battery was out, now I have dried it out using rice and instant oat! Before, ...
0
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1answer
90 views

Why services that need to receive a signal, like Bluetooth or GPS, drain cell-phone battery?

The title is self-explanative. This is an emprically contrasted fact for cell phones, although I don't know why this happens. As far as my understanding goes the signal receiver is a passive ...
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2answers
132 views

Tracing a mobile phone's location without GPS [closed]

Without GPS, one way to locate a phone could be through trilateration. However, this would require the phone to be connected to 3 (or maybe even 4?) base stations to accurately obtain the phone's ...
61
votes
6answers
10k views

What makes smartphones tilt-sensitive? Will they retain this ability in zero-gravity conditions?

Most smartphones are tilt-sensitive, but what device makes this possible? Additionally, how does it (and the sensors associated with it) work? Also, since the working of these sensors seem, almost ...
3
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3answers
2k views

Why do cell phones sometimes interfere with amplifiers

I have an old Sony amplifier (TA-F117R) next to my desk where I keep my cell phone. Sometimes I put it ontop the amplifier, because it is pervecly alighed with the surface. When I hang some call up ...
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1answer
495 views

Implications of 2G network demise for basic (SMS/USSD) device communication

I'd like to know if basic GSM functionality will be affected by the phasing out of the 2G networks. I have several devices with modules like SIM900, old 2G Enfora, etc. and they use SMS and USSD for ...
13
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2answers
4k views

Why do only high-end phones support a lot of LTE bands?

Most lower and middle end phone only support 3/4 LTE bands. High end phones, like the iPhone, or flagships from Samsung and LG also support a lot of bands. iPhone 7: 1, 2, 3, 4, 5, 7, 8, 12, 13, 17, ...
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2answers
9k views

how much power is radiated by cell towers?

I want to know how much power is radiated by cell towers of GSM (1.8 Ghz), 3G (2.1 Ghz), 4G (2.6 Ghz) ? I want links to references if exist.