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

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1answer
26 views

Best way to make connection with rubber contact pad

I dismantled a push-button telephone and I am want to control it using a Raspberry Pi (A+) to trigger the button presses. The phone has a grid of 12 (+2 special buttons) contacts that correspond to ...
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0answers
48 views

Understanding Phone Service from Cable Companies [closed]

Since communication technology is considered part of EE, I thought I would pose this question here - hopefully it is on-topic. Cable companies like Comcast have been offering home phone service for ...
1
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1answer
53 views

How frequency generator in telephone works

I was doing some research, on how telephone works, and I found that when user, click numbers they are converted to frequency and passed to wire. I want to know how the frequency generator work, what ...
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1answer
47 views

External power supply a mobile phone

I have an alarm device. It convert 12v to 4,3V to the phone. It's outputs are 4.7V, GND, and two output to the phone buttons If the inputs loop of the alarm device is opened that means the wire have ...
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3answers
166 views

Approval before using built portable charger on a smartphone

I've finally managed to set up a more efficient portable charger that uses 8 AA alkaline batteries(actually not so efficient). Schematic: simulate this circuit – Schematic created using ...
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2answers
68 views

Why are telephone/internet lines less susceptible to surges than power lines?

(I know nothing about electronics, so excuse my ignorance.) I understand surge protection for power outlets are necessary, or at least recommended, for expensive electronics. But are telephone lines ...
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1answer
78 views

Possible to make Touch Tone Phone Ring with no phone line?

I am making an "Activity Board" for my toddler. I'm wanting to make an old touch tone phone ring when he pushes a button or picks up the phone. I am hoping someone can help me or point me in the right ...
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1answer
62 views

operating landline phone via mobile phone [closed]

I am making a small DIY project to operate my wired landline phone (twisted copper cable) using my mobile phone. Use cases: Dial number on landline via mobile device. Receive incoming landline calls ...
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1answer
51 views

Using european telephone cables for own DC power delivery

I have european telephone cables running through my walls to each room, without any connection/socket. Well... we really do not need any hard line telephone connection and I am into DIY projects, so I ...
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1answer
66 views

How to filter out ringing current in a local battery telephone system?

We have a network of manually-switched local-battery telephones. Here is depiction of the circuit in one telephone: ...
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1answer
59 views

Charging several phones in the field

There's an outdoor area I'm working on, and I want to build a small station where people can charge their phones. There's no access to house power in the area. I've looked into solar chargers, but ...
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1answer
55 views

Connect Headphones to phone [closed]

Using standard headphones, is it possible to connect it to a standard non-VOIP wired phone? What connector would I need, or how could I rewire this? Headphones have some kind of 3.5 mm jack, Phone ...
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1answer
239 views

How exactly do 1950's rotary phones receive phone calls? [closed]

What happens start to finish. For example, how does the signal get from the central office to the phone and what mechanisms within the phone move to signal that a phone call is coming?
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1answer
112 views

How would you increase voltage to drive an LED yet also keep it limited?

I have somewhat of a special situation. I have a telephone system at the performing arts center I work at, and I need to make some of the phones flash an LED with no audible ring. My predecessor came ...
3
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1answer
428 views

How does a telephone hybrid transformer work?

Suppose the following circuit: I can see how an incoming signal (Kim's voice) wouldn't be coupled with the lower pair, but I can't see how an outgoing signal (Ron's voice) only goes through the ...
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2answers
117 views

How does electrical interface on multi-subscriber FDM telephone line work?

I am wondering how the electrical interface for a frequency multiplexed telephone line works. If two senders are connected to a single line, how is it that the final output stage amplifiers don't ...
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1answer
62 views

Mobile phone explosion [closed]

There have been several cases of mobile device explosion while charging and using to make call. There is also cases of power bank exploding while using it to charge phone [but not plug to ac ...
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1answer
79 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 ...
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1answer
145 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.
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1answer
106 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 ...
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2answers
289 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
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1answer
103 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 ...
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1answer
48 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 ...
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2answers
199 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 ...
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1answer
109 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 ...
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0answers
114 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. ...
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1answer
748 views

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

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 ...
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2answers
57 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 ...
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1answer
123 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 ...
0
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1answer
202 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 ...
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0answers
184 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
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2answers
96 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 ...
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1answer
223 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
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1answer
180 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
202 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
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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 ...
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2answers
262 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 ...
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2answers
861 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
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1answer
324 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
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1answer
262 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 ...
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1answer
360 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
165 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
180 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 ...
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votes
1answer
139 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
193 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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3answers
1k 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
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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
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1answer
125 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 ...
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2answers
399 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
129 views

What is this electronics component?

What is the yellow component shown here? This is off a Outlet USB phone charger.