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

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2answers
118 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 ...
-2
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0answers
14 views

splicing a 25 pair telephone riser [migrated]

I have a phone riser in my apartment (25 copper pair, originally but only 18 left going past my floor) carrying Verizon phone service. I have to move it over 3' to a different wall, so that means ...
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2answers
57 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 ...
1
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0answers
20 views

Is a DSL splitter required, if only a Modem is attached to the line? [migrated]

Annex B is the current standard for digital subscriber line (DSL) in Germany. A DSL-splitter is an analog L-C-filter to separate the POTS (plain old telephone service, like voice and ISDN, FAX) ...
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2answers
88 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 ...
2
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0answers
50 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
77 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
58 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
61 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
79 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 ...
0
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0answers
34 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 ...
-2
votes
1answer
89 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
votes
2answers
132 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
votes
0answers
31 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
174 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 ...
0
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0answers
32 views

How to adapt 3.5mm to 4P2C?

I am trying to make a cable so I can plug my old phone into my new smartphone. It has a 4P2C connector, and I have tried splicing the 4P2C cable and a 3.5mm cable together but it didn't work. How ...
15
votes
6answers
2k 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
62 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
206 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
101 views

What is this electronics component?

What is the yellow component shown here? This is off a Outlet USB phone charger.
-1
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1answer
78 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 ...
2
votes
1answer
111 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
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1answer
56 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
432 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
120 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
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2answers
137 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
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1answer
167 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
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0answers
97 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
61 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
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1answer
135 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
109 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 ...
0
votes
1answer
59 views

A voltage regulator that is controlling a voltage

My scenario is that I am having a circuit which having 12V as the input voltage and works beween 8V to 15V. I want to limit this circuit in a way that if the input voltage drops below 12V criuit ...
1
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1answer
127 views

Power a circuit and read output from tablet microphone port

I have a project that I'm currently powering with a AAA battery, providing 1.5v to a simple 555 timer circuit. The output of the circuit goes through a voltage divider into the microphone input of a ...
1
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2answers
279 views

Land line circuit suggestion / DTMF project

I am hoping to make a system that I can call in and using DTMF chip can control few things. I don't want to use a cell phone so it has to be a land line, however, it has to be automated so when the ...
11
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5answers
2k views

Control the hardware of an old phone using a Raspberry PI

I have a very old phone (60 years old) and I want to control its part using a Raspberry PI: Microphone & speaker from the head set The bell The dial wheel I have the electric circuit but don't ...
3
votes
1answer
129 views

telephone hold-on music

Can someone explain the following telephone hold-on music circuit in throughout manner because I am still learning how to simulate circuit using gnucap? When TR2 does not conduct, it switches off TR3 ...
1
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0answers
267 views

Using Java applet on a cheap Nokia phone to control Arduino via Bluetooth [closed]

I've built a nice wheel robot prototype with my kid. He had a broken R/C bigfoot truck: we've replaced its 'brains' with Arduino Pro Mini, DC motor drivers and HC-05 Bluetooth chip. Currently we ...
1
vote
2answers
97 views

Phone jack schematic and datasheet meaning

I am making an Eagle Cad library for this part, and I want to make sure I am making my part correctly. On this datasheet, http://www.switchcraft.com/Drawings/35rapc2av_cd.pdf, I am assuming that: ...
0
votes
1answer
173 views

Connecting phone using copper power wires

I want to install a video door phone (intercom) in my home, for this I have done a pre-wiring of 4 individual copper wires (normally used for home electricity) and the total length of wires is about ...
2
votes
2answers
299 views

POTS DAA circuit explanation

I am puzzling over this schematic, the datasheet just says to follow their recommendations exactly, and doesn't give explanation of the IC actions or circuit functions. The lower half is easy to ...
1
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1answer
54 views

Sampling phone line

I want to connect phone line to my PIC's ADC to sample signal changes without interfering the line. Human voice and DTMF signals are all under 4kHz level. So, I am hoping that any 18F PIC can do ...
0
votes
1answer
88 views

Connect 2 line phone to a 4 line system

There is a corporate phone system that uses multi-line phones. The idea is to connect a cheap 2 line phone only for answering calls without adding a line. Can this be done? Just connecting in ...
1
vote
3answers
206 views

Can a display landline phone instrument be made to work without a separate electrical connection

Since phone lines can supply power, there are landline phone instruments which work without a separate electrical connection. Typically these have no display etc. There are also those instruments ...
0
votes
2answers
98 views

What are these character sequences in connection with DTMF and a modem (telephony)?

I have a telephone, with which I dial a modem (analog, no ISDN) in order to send DTMF tones. If basically works, I receive something! For each key I press on the telephone I get a string like follows ...
0
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0answers
384 views

How can I isolate a short (in a mobile phone in this case)

I have a Nokia 6030 cell phone, and it's been serving me 7 years. It developed an interesting problem, which looks like a short of some kind: the battery drains very fast, for an hour or so, and the ...
-2
votes
1answer
1k views

Glitchy Touchscreen Caused by Charger [closed]

I recently bought a Nexus 4. I had a couple of spare chargers laying around. I used a charger that apparently had an issue exactly like: https://www.youtube.com/watch?v=mrpBTG0a6K8. If I used my own ...
-5
votes
2answers
190 views

Calculator with phone keypad question [closed]

I am not an electronic person and found this site in a my quest for the perfect calculator. I use both a phone and calculator for calculations and find the back and forth to cause me to make errors ...
0
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1answer
146 views

Powering cell phone from arduino

I am a beginner in electronics and I want to ask you a simple question. Can I power my old SE w200i directly from arduino, using resistive divider like this one: ...
4
votes
3answers
687 views

How to draw current from a telephone line?

My landline phone comes with a lcd display caller id and clock. Even if I remove the 2 AA 1.5V batteries, the lcd still shows time even if I'm not busy on a call. The lcd has no other source of power ...