Questions tagged [telephone]
A telephone, is a telecommunications device that converts sound into electronic signals suitable for transmission via cables
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How is message waiting conveyed to home POTS phone
The message-waiting indicator is often described as a LED that lights up when you have voicemail. It may be voicemail on a voicemail service provided by the overall phone service provider.
I haven't ...
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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 lower ...
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Intercom from old corded telephones
I'm experimenting with making a simple intercom from two old corded telephones.
I'm including a buzzer and momentary switch on each end for an incoming call alert.
Below is the circuit I made using ...
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Spiral hoar frost and spiral device around telephone or electric landlines
I live in Germany.
When I travel by train, sometimes there are cables that run from pole to pole parallel to the train track.
From the lack of insulation between wire and pole, I guess these are ...
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6V 3W solar panel and to charge phone through a DC converter XL6009E1 via a 12V 2A car charger [closed]
I have a 6V 3W solar panel and want to charge phone with it, i have tried a dc converter XL6009E1 via a 12V 2A car charger it shows charging but battery power did not increase
I am scared of using the ...
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How to connect a Battery Charging board / Management system, directly to a phones PCB to provide an alternative port for charging?
I have a Welcome phone (a no name phone) where I'm hoping to use the standard phone charging port for other uses. So I thought that I could solider a Battery Management system (BMS) directly to the ...
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Connect two old pulse-dialing phones
At work we have some old pulse-dialing (rotary) phones. We want to connect two of them to make a simple intercom. Whatever the number is composed (even one single digit) the other should ring and of ...
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Why are old RJ-11 modular telephone cables reversed?
I've checked all my old modular phone cables and all of them have the terminal plugs attached so that the wiring is reversed. That is plug 1 is Black-Red-Green-Yellow and at the other end of the ...
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Connecting with a mobile phone over a 2-3 ft distance, and not beyond that
I have a device that I want to connect with a mobile phone at 2-4 ft, but not if the phone is further away than that. What signal or design can I use to accomplish that?
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Swapping a number pad from telephone to synth [closed]
I’ve recently acquired from the trash a toy synth keyboard piano.
It works, but I wanted to create a stand-alone number pad from an old telephone.
I’d like to know if it’s possible and how to do it if ...
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Hold button for UK Landline telephone
We have retro rotary telephones, and I'd like to make a hold button for the one in my office in the UK.
This is literally a "ye olde rotary phone" (1940s) made from bakelite
I have fairly ...
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Capturing the output of a DTMF phone (without keypad access) [closed]
I wanted to make a gift for someone that uses a cheap DTMF phone as a controller.
I thought I could just take it apart and rewire the keypad's ribbon cable but it turns out that the whole thing is ...
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What component could be
I have a VDSL telephony socket with some electronics in it. I reverse engineered the PCB, but there is one component I cannot identify at all. Look like a 0.25W TH resistor, light-blue body and a ...
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How to translate from voltage in a circuit to a command on a phone? [closed]
Basically, what I am trying to accomplish is getting my phone to make a call (to a specific number, say, my brother's), when a certain voltage threshold is exceeded. However, I have no clue how have ...
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15 W USB ports in car [closed]
My car has two 15 W USB C ports that will fast charge my phone, but they are not powerful enough to super fast 2.0 power my phone (S21+). Is there any kind of device that would take the two 15 W ...
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How does a UK analogue telephone detect that the caller has hung up (disconnected)? [closed]
Scenario
This is a question regarding the design of UK analogue telecommunications equipment and the consequent design impact that is necessary for a router duplicating those signals. It is asked so ...
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What is this part in a “retro” phone?
I’ve got a recently manufactured “retro” landline phone that I wanted to scavenge some parts from, made in 2012 I think. I’d like to be able to do something with the ringer, which appears a lot ...
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Can i safely use RJ11 and 24 guage wiring for hobby leds?
I would like to supply power to a bunch of LEDs (a dozen or so) on a model train layout. I would like each light to be modular, so I could easily unplug a building and replace it, etc. The LEDs are ...
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How were four wires replaced with two wires in early telephones?
In this video, when A wanted to talk to B, a microphone was connected to a distant speaker using two wires (A → B).
When B talked to A, a copy of above was used in the other direction (B → A) using ...
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Replacing phone battery with power supply
I have an old phone (nexus 5) that I want to use for a project. I need to replace the battery with a permanent power supply, I've found the 3 pins of the battery and made a breakout connection with 1/...
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What is the reason that this RJ11 cable can't be connected to this socket? [closed]
I connect one end of this RJ11 to my router's WAN port, and I connect the other end of it to a 3-pin plug, and I connect that 3-pin plug to the phone jack, but when I try to connect the RJ11 cable to ...
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Disable ring on land line phones
Years ago I bought a device at Radio Shack that disabled ringing on household phones. It was a very small box with a modular receptacle on one side, a pigtail on the other with a modular plug, and a ...
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Solar lamp/phone charger output current too low for modern phones
I am building a solar lamp/phone charger following this page, with the circuit here below.
I have two 18650 batteries in parallel. The charger module is the usual TP4056 taking 5 V input, and limited ...
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Three-wire old phone to RJ11
I'm trying to connect an old phone's three wires (white, red, green) to my home line VOIP-4-wire (black, red, green, yellow) but I don't know where or what to connect.
I have read this:
How to ...
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Phone battery charges linearly [closed]
I think this is probably a bit basic, but I've tried googling and have posted elsewhere.
The question is vey simple. I've recently bought a new smartphone, with a standard lithium battery. Every other ...
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What do you call the yellow and black conductors in domestic telephone wire?
Any wannabe telco guy can tell you that the green and red pair are called "tip" and "ring" respectively, most can tell you the historical reason why. That's not what I'm looking ...
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Solve this puzzle: Car lighter port blowing phone battery [closed]
I brought my Jeep in for work, and the mechanic let it die.
When he jumped it, he somehow blew my amplifier. He was able to fix that.
A few days later, I plugged my phone into the car lighter port and ...
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Connecting 4P4C RJ9 Headset to 3.5mm pc port
I have a Plantronics CS520 Binaural headset that I'm trying to connect to my PC instead of a desk phone.
I'm using a TRRS with T connected to speaker+, R disconnected, R connected to Mic, and S being ...
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As a child I licked a landline telephone cord plugged into the wall
As a child I licked a landline telephone cord plugged into the wall.. It felt like it physically moved/shot me backwards.. Could this have happened or was it just a sensation from getting electrocuted?...
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How was the first overseas phone call possible back in 1927?
I was watching the Peaky Blinders TV Series when something triggered my curiosity: If there were no satellites, nor underseas cables, how come the characters were making overseas phone calls?
After ...
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Analog telephone circuit and TEA1062 [closed]
I am currently working on an analog telephone project.
I have some questions.
ICs and Central are below:
Central: KX-NS500 (gives 28VDC)
DTMF receiver: MT8870
DTMF generator: HT9200B
MCU: ...
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Fast charging 2.0: 7V×2.5A, 9V×2A or 12V×1.5A?
The FastCharge 2.0 standard has these charging specifications in the exact same charger (a VoltCraft car charger):
5 V up to 2.0 A (10 W max.)
7 V up to 2.5 A (17.5 W max.)
9 V up to 2.0 A (18 W ...
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Choosing a replacement electret microphone
I'm trying to select a suitable replacement electret microphone for an analog (POTS) phone. The existing electret is completely unmarked so I don't know its part number or parameters. I'm not well ...
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Can I extend a single twisted pair DSL line using a coaxial cable?
I'm in the process of setting up a DSL modem/wifi router, which should be connected to a phone line that uses a single twisted pair. However, the phone line enters my house in a slightly inconvenient ...
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Make old telephone ring
I recently found one of those old rotary dial telephones in my garage and amazingly it still is fully functional (I tested it by hooking it to the phone line). As I have no use for it as a telephone ...
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5G and aircraft? [closed]
I just read the statement of a company,
"We are frustrated by the FAA’s inability to do what nearly 40
countries have done, which is to safely deploy 5G technology without
disrupting aviation ...
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Driving two bell coils from an old phone with 90 V, 20 Hz AC
I have an old phone which stopped making calls, but the ringer still worked. I used a phone ring generator that generates 90 V, 20 Hz AC to test this. I want to place this ring generator inside the ...
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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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Telephone headset adaptor weak microphone and speaker sound
I have made a simple adaptor for a telephone P4C4 -- RJ9 -- separate headset output (The wiring diagram of a telephone handset can be viewed in this wikipedia article) to two TRS jack for an ordinary ...
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Make a faux call on old 1950s touch tone phone [closed]
I have a 1950s ice cream shop and just bought a vintage touch tone phone. It works if I connect it to a phone line but I won't be doing this. What I really want to do is pre-record messages that will ...
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How does this old telephone ringer work?
I bought an old rotary phone with the hopes of cannibalizing it for a doorbell/intercom thing in my apartment building. It looks absolutely marvelous inside:
However, I'm having trouble figuring out ...
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What does GSM 900/1800 mean?
I was looking at old Nokia 3310 phones, which have GSM 900/1800.
I did some research online from a government website, along with some Google searches, to understand what GSM 900/1800 means. I got a ...
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Can lightning strike into the phone line damage electronics in the house through the ADSL modem?
I was always wondering about the following:
If lightning strikes directly into the phone line outdoors, can the excess power coming from the phone line jump over the switching power supply of the ADSL ...
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How did phone networks do switching in the days before programmable ICs?
How did phone companies and companies that made PBX's do switching with discrete logic or simple, non-programmable ICs?
The caller would type in a number, so the system is receiving a sequential code, ...
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What electric part is on this manhole cover?
Here's a photo of a manhole cover
The letters form the word "ТЕЛЕФОН" ("telephone" in Russian in ALL CAPS).
What is on the picture in the center? Perhaps it is some part that should be associated ...
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identification SMD 3 Pin 3x1.5mm code 4B C39 for stereo camera
I am trying to build stereo camera using android or iphones. The pcb is from a wired selfie stick and works well. By using 2 pcb's with one push button, simultaneous photos can be taken. I have looked ...
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Why telephone dc voltage drops to about 8 volts? [closed]
I found out that the DC voltage supply is about 48 volts in the central office, and the typical line impedance is about 600 ohms. Also the typical current in off-hook state is about 20mA.
So with a ...
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Two phone batteries connected in series not working
I have two, fully charged, 3.7V standard Nokia phone batteries, that I want to connect together to use as a 7.4V battery, I connected the (+) of one to the (-) of the other, and then tested it but it ...
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Is it safe to wire a telephone to a breadboard?
I am trying to connect a hardwired 2554 telephone set. There's only a few inches of slack wire coming out of the phone since it appears it was just cut there. I managed to get about half an inch of ...
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Convert 60V AC 50Hz to 60V AC 25Hz
The setup is a 240V 50Hz AC transformer outputting 60V 50Hz AC. Connect this power supply (with a push button) to an old telephone and it rings the bell on command, but unrealistically fast.
I need to ...
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