A telephone, is a telecommunications device that converts sound into electronic signals suitable for transmission via cables

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1answer
22 views

Powering an External Phone Ringer - Straight Talk Home Service

My dad is having difficulty hearing his cordless phone ring in his shop, due to ambient noise. He has the phone connected to a Straight Talk home phone service device. So, there is no legacy analog ...
0
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0answers
20 views

Device for sim to cable phone [migrated]

I know that this question might not right here.. But i do not know where to post it else. Is there any device, which I can put a sim card in. And then connect a good old cable connected phone to it?
0
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1answer
63 views

Echo effect during phone call [closed]

What causes echo effect in telephone lines during phone calls? Does it mean that someone is spying on telephone line or? When I talk with some people, it happens, and with some of them not.
0
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1answer
61 views

5V charging through ATX PSU? [closed]

I've an ATX power supply and I'm trying to charge my Nexus 5 phone. I connected USB female (from an old PC) to +5V and GND and shorted the DATA+ and DATA-. My multimeter shows 0.400A when I connect my ...
2
votes
2answers
71 views

Software based Caller ID project- Problem with getting caller ID signal

Nowadays, I am trying to make a Caller ID project without using Caller ID ICs. Firstly, I have done a lot of research in Google to get information of phone lines and their electrical properties. I ...
0
votes
1answer
66 views

What would prevent DTMF tones being recognised (modem to modem)? [closed]

A bit of back story: the SEGA Dreamcast had a dial up modem which was used for online play, in the absence of dialup ISPs it's now common practice to directly connect the DC to a USB dial up modem and ...
1
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1answer
45 views

In current mobile phones, what are some specific techniques that prevent handling noise (rubbing, jostling) from being picked up by the microphone?

I've noticed that when using my smartphone the vibrations from my actions aren't picked up, or are picked up very faintly by the microphone. I've worked quite a bit with microphones and I know it must ...
-4
votes
1answer
134 views

I want to charge my phone with AAs. How do I get that 5V output with max amperage (Would love to draw that 2.1A)

I was just wondering around, looking for how to charge my phone on the go. Because Wednesday morning I'll go camping. I just don't want to buy a cheap chinese power bank to charge my phone once. And ...
0
votes
1answer
78 views

Old-School RJ11-Based Phone

On an old-school RJ11-based telephone system, which of these statements is accurate: 1) Each wire contains a waveform constructed from the sounds detected by one party's handset OR 2) One wire is ...
0
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0answers
88 views

Li-ion powerbank UPS + DC boost converter

I have a philips cordless landline phone and its power rating mentioned in its OEM ac-dc adapter says output of 6v 500mA. the problem is that in my place we have intermittent power failure, and since ...
-1
votes
0answers
87 views

Using a 5v USB Wall Charger on a Zenfone 2 with +9v battery? [closed]

I ordered the new Zenfone 2 and it only comes with the "Boostmaster" quick charger that outputs 9v and 2A. Also, I saw pictures where the visible part of the battery in the phone says "+9v 2A" on it. ...
-2
votes
1answer
125 views

How can I power a cellular phone for a week with a car battery or other type of battery?

I am about to start construction of a new house, and unfortunately the property is not near where I live. I wanted to keep an eye on the construction site (No electricity) to make sure workers are ...
0
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2answers
53 views

In a power supply, the current is a constant or gives whats the component/circuit need ? [duplicate]

I everybody, sorry for my english :D . i'm a begginer of electronic and i'm learning a lot of electronic component, voltages, current and so on. My question is about a charger (phone charger for ...
-1
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0answers
27 views

Qualcomm and phone power comsumptions

There are some links about qualcomm and phone power consumptions: http://www.notebookcheck.net/Qualcomm-Snapdragon-800-MSM8974-SoC.103706.0.html ...
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0answers
15 views

MU-LAW COMPANDER for a 10-bit Quantzer … ? how many level will be needed to represent the lowest 30% of the signal for U=0 and U=10

for a 10-bit Quantzer how many level will be needed to represent the lowest 30% of the signal for U=0 and U=10 ? I know it it is u=0(simply no compression) so # of level = 0.3(2^10) which is = 307.2 ...
0
votes
1answer
90 views

Hardware reference design for a phone [closed]

I want to make a simple box with one button. Pressing the button will send a SMS Text message to a preprogrammed phone number. I have not designed a phone hardware before so looking for some simple ...
1
vote
1answer
95 views

What's the best phone cable for DSL? [closed]

I want to know what cable I should be using to connect my demarc to my DSL modem. When I plug in my DSL modem in the utility room (which is about 20' of wire from the demarc) I get a pathetic 4Mbps ...
1
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0answers
100 views

hijack project microtransformer doesn't work well

I am working on a project that need to get energy harvest from smartphone headset jack.I find hijack project has a solution.the energy harvest circuit of it is below: it use coilcraft transformer ...
0
votes
2answers
82 views

Power-line communication to household!

Most households in this planet have multiple 'wires' - one for plain electrical power, one for telephone, one for internet and one for cable TV (there may be more). I had heard of PLC ...
-1
votes
1answer
91 views

What is the minimum voltage requited to charge a cell phone? [closed]

When charging a cell phone, what is the minimum input voltage to the phone required not the battery directly, but the actual phone? Is it actually five volts that the wall charger puts out, or can it ...
3
votes
1answer
121 views

How to automatically test the audio quality of a telephone line that randomly goes bad?

I am a computer scientist and I'm working as sysadmin of a small firm where I've been managing also the telephone system that my predecessor put in place. Albeit I don't really have the skill set ...
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2answers
160 views

Landline listening

I still have a good old landline at home. But I miss the easiness of cell phones where you can just see a list of missed calls. I'm a MSP430 Launchpad hobbyist and I'm alway looking for some little ...
8
votes
1answer
1k views

Question about old telephones (late 70's - early 80's)

This question refers to old landline telephones that would have been used in households in Sweden in the late 70's and early 80's. I would think that this was probably similar to phone technology used ...
0
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2answers
105 views

Crosstalk vs interference

I don't even clear about the differences between crosstalk and interference. Could you explain me please? I just know that cross talk is the leakage power from other sources, whereas interference is ...
0
votes
2answers
401 views

5 volt generator

first time question, and not much of an electrical guy. so please be patient. My dad however, is an electrical engineer, who loves little goofy gadgets as most engineers do. For Christmas I want to ...
3
votes
1answer
218 views

simple GSM SIM modem

I'd like to build a prototype of simplest possible GSM device - a simple modem with SIM holder, capable of logging on to the SIM's provider network and nothing else. It's meant to be used as a GSM ...
2
votes
1answer
154 views

LCD connector repair [closed]

Does any one know if it is o.k to run a soldering iron over the connector with the fine black traces on in the photograph attached(or below I am new to pic posting :D)? I have an office kitted out ...
1
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1answer
169 views

Old phone continuity tester

An old man I used to work with had a set. Two old handsets with two conductors coming from them. It had a 9v power supply, I believe. We used it to trace existing interlock wires, hundreds in one ...
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1answer
122 views

Audio amplifier not working after changing source (LM386L)

I have this simple amplifier here: I tested it with a regular PC audio jack input. Works fine. The problem is when I try to use it with a telephone (Panasonic KX-DT333, 2.5 mm jack). To be sure ...
0
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2answers
135 views

Convert a ringing telephone voltage of 90V AC to 3.3V 1000mAh DC current so that it only triggers when the telephone is ringing?

How can I convert and step down a ringing telephone voltage of 90VAC current to 3.3V 1000mAh DC current so that it only triggers when the telephone is ringing? Bridge rectifier? Inductor? Step Down ...
1
vote
0answers
61 views

Building own (FAX) modem

I was thinking of constructing my own simple modem based on a micro controller, such as an Atmel ATMega16. I can get a USB stack for the micro, so that part is one thing, but I'm having trouble ...
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votes
1answer
102 views

Is full duplex speakerphone available as an embedded feature? [closed]

Full duplex speakerphones are clearly a complex signal processing problem, since you have to filter the device's speaker output from the microphone pickup. But is this a feature that is presently ...
0
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2answers
159 views

How to make an easy oscillator?

I want to make a very simple oscillator that produces the sound of telephone ringing (I want to make a ringer). I will not connect it to a telephone so the quality of the sound is not important. I ...
0
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0answers
64 views

Multiple phone (pstn or gsm) numbers in a single modem

Is there any way to receive calls to multiple numbers in a single modem in case of PSTN (land phones) or sim in case of GSM? I already know that for GSM, there are multi-sim modems available but I am ...
0
votes
3answers
680 views

RJ11 socket in Eagle libraries?

I am trying to add RJ11 (telephone wire) sockets to my PCB on Eagle but am having trouble finding it in the libraries. Is this a standard socket that is included or do I need to install some external ...
16
votes
6answers
3k views

Unplugging a router from the wall socket

When the internet appears to have crashed, the service provider invariably gives this advice as a first line remedy: unplug the router from the wall socket, then wait 5 minutes, then plug it back in. ...
0
votes
1answer
94 views

G.711 for dummies

I am in midst of some online telephony course, and there are questions regarding which I have no one to ask but this community. G.711 volume encoding. I have some difficulty to understand how ...
1
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2answers
369 views

How ADSL Demodulates (restores the order) the signal for dummies

I am not an electric engineer so sorry for questions that might miss some fundamentals. I am trying to understand the ADSL modem. The ADSL modem sends the data over different frequencies in ...
0
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4answers
122 views

What is this electronics component?

What is the yellow component shown here? This is off a Outlet USB phone charger.
-1
votes
1answer
94 views

bluetooth headset with LCD and memory

I was wondering if it is possible to create a bluetooth device which would have a LCD screen and some memory (1kb) for making and receiving calls. From my research ( and I am far from an EE, but ...
4
votes
1answer
201 views

Wireless telecom system (cellular with Erlang and spectral efficiency)

We have a spectrum of 20MHz that we will use on a wireless cellular system, which requires 50kHz per channel. The system is using cluster size K = 4 and the radius of every cell is R = 1 km. a) ...
0
votes
1answer
84 views

Cell in Cellular communication

When they talk about the "cell" in cellular communication, they often refer to the shape of hexagon. If I am correct, this is probably the coverage area of the transmission base tower. SHouldn't be ...
2
votes
2answers
795 views

Is it ok to use an old phone as an universal battery charger?

We know that a charger is just an adapter that supplies a constant voltage (5 volts usually). The actual charging circuit is in the phone itself. With a bit of soldering and wiring, can I use my old ...
0
votes
1answer
172 views

The simplest circuit to translate from RJ11 to my PC [closed]

Assuming that you don't want to get a functionality, it doesn't need to be a DSL modem, you want to study some signals and you only need an input starting from an RJ11 and going to a PC; what is the ...
1
vote
2answers
206 views

The math and the physics behind POTS phone lines

Since high school you learn something about Fourier Analysis and you can easily grasp the idea that a given signal that is variable over a given timeframe, is composed of multiple sub-signals with ...
1
vote
1answer
280 views

2/4 Wire Conversion Circuit For UK Telephone

I am currently trying to build an op-amp circuit which allows seperation of send and recieve signals from the UK telephone line (or a simulation of the telephone line). I am having difficulty ...
0
votes
1answer
215 views

Telephone “off-hook” indicator

I have a 2-line telephone that shows when a line is in-use (i.e. if an extension is picked-up, the indicator will light up on the phone). The two lines are being supplied via 1 RJ-11 cable (1 line on ...
0
votes
1answer
67 views

looking to capture an infared code

I am trying to get an infared signal being sent from an emitter (think along the lines of a remote control). I know I can use a fotoransistor on a breadboard to capture/detect the signal, but I have ...
0
votes
1answer
252 views

Patch-panel for phone splitter

I need a phone splitter (RJ11) to split 1 signal into 4 or more outputs. That's no problem, those can be bought in any store. But I was wondering if I can use a RJ45 cat6 patch-panel?
3
votes
2answers
186 views

Door phone audio signal to pc soundcard

I need to interface door phone system to a pc soundcard to listen and talk to the external unit. The door phone to interface is an as yc/200 of BPT and its a classic analog 4+n wires Door phone ...