Connecting Two Landline Telephones Together Update.
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- Опубліковано 25 сер 2024
- I recently made a video, where I demonstrated how two ordinary landline telephones can communicate with each other, by plugging the phones into each other, and adding a 9 volt battery in parallel with the telephone wiring. After I made the video, some of the comments suggested I should have added my 9 volt battery in series with the phones, and when I followed your advice, I realized you were right, and it worked far better in a series circuit, so I wanted to update my video, and thank some of you guys, who informed me that my parallel circuit was inferior to a series circuit. One additional note on the Bell voltage. I've been informed by a gentleman who use to install telephones, that the bell voltage is typically 48 volts AC, but after searching around, I noticed a rather large variety of opinions on what it should be.
Former AT&T lineman here 👋🏼. Ringing voltage can vary, but what is produced at the source in the central offices out to the lines is 105 volts ac. It can drop some at the home depending on the condition of the lines. Talking voltage was 48V DC. The COs have giant banks of 48V batteries and diesel generators for backup in case the power goes out so people can still call out in case of emergency. Also, when it’s raining and working on the lines you can get a Hell of a shock that vibrates your whole arm if you hands are wet. Forget about it if someone calls in on the line you’re working on. It won’t kill, but it’ll make you think twice before grabbing that line again. 😆
As a former lineman I appreciate your input, It's interesting how many different answers I get on the ring voltages,
What would really get you is if you touched the wires when someone was using a rotary dial.
What would happen?
What i would try is a minimum voltage. I know as little as 36vac can ring an analog bell but I believe the digital ringers can trigger on less.
@@fuzzym30 I was able to ring one of my telephones with 41 volts AC, but it seems to be different from phone to phone.
Nice. We should call this invention an “intercom”.
Cannibalize the phones, too, and mount the speaker/mic right inside the wall. Then, take the receiver button and reverse it so that pushed down = talk!
I bet folks with large homes would love this!
😅
Nah, that’s been taken already.
We might be able to use this in fire alarm panels for high rises
@@AffordBindEquipmentThats the joke/sarcasm
@@adventureoflinkmk2 got it!
As an old school phone engineer I can tell you most people leaving comments are correct about the tip/ring voltage being 90V but the little known part is that its at 20 Hz as phone system predates national electric grid that went with 120/240V at 60Hz... That's why a hot phone wire grabs you so much harder than 120 electric... The lower frequency Hz contracts muscles and higher frequency Hz releases muscle...
Higher frequency does not release muscles, there are just more opportunities for you to let go of the wire (for example) as the sine wave crosses 0v more times per second than a low frequency
@@gtjack9 well as someone that has launched themselves across a room due to a bad joke played by co-workers (cross circuit break bars with a known insulation crack --not known by me-- during a ultra low to ultra high freq. sweep) I can attest that at the low freq. my muscles contracted deeply and held on tightly and by the higher freq. flexed beyond normal brain limited flexion and sent me flying (jump) backwards and cleared several workbenches before greeting the wall at height... So my experience begs to differ...
@@user-dw9ou9sg2p I’m not sure, your experience seems to support what I said?
@@user-dw9ou9sg2pyour personal experience does not negate facts
@@user-dw9ou9sg2pwas gonna say that's the same reasons why DC voltage locks you in tight. There is no break in polarity like it is for AC
The double copper pair for voice communication was a technical marvel.
Even in a power outage, you could still pick up the phone and dial.
Old Army field phones, if the batteries died (a pair of D cells), you could shout into the earpiece and it being a diaphragm speaker, would induce enough voltage and current to be weakly heard at the other end. Ringing was by hand crank generator. All voltages, currents were the same as commercial phones, but you'd have to go through the unit switchboard so they could connect you and dial out via the mag drop, if connected to the base network.
So, while available voltage was 48 VDC for the central office, at the customer premises, it could actually drop all the way down to 3 VDC and still work. Ring still needed 90 - 105 VAC/20 HZ.
had a circut that stepped idle voltage up to 240v that was stupid, but interesting. was 60Vac in australia for a ring
Yeah, but the dialing process actually required external power. The central offices had batteries and generators
@@CODMarioWarfare_"yEaH bUt!!"_
_No _*_stink_* it took power to operate at a massive scale, ya dingus!
Hahaha, sorry. Please don't be mad, I couldn't help myself. Not trying to be mean, just being playful in poking fun at you bringing up the obvious 😅
Edit: I potentially misread it and assumed you were referencing the general operation of the typical civilian networks instead of the simple act of sending a ring/call command or whatever (I'm ignorant to the technical aspects of phone systems). If that was the case, I admit to being the stinker 😅
@@illitero I mean the original comment implies that this marvel of engineering could operate without external power
Ah, this is such fun to come across! Reminds me of some fun times back in the mid 1970s… I used a version of this idea as a teen to create a 24/7 ready live phone connection from my basement bedroom in my house to my best friend’s house using just two Bell System Western Electric telephone handsets, a couple hundred feet of speaker wire and a 9-volt dry cell battery. I dug a slit into my lawn to hide the wire run around from the back of my house to the storm drain manhole cover near the street, then down and under and across the street, all around the back and up to my friend’s 2nd floor bedroom.
I was overwhelmed to realize I could hear pretty much every conversation in the house so I needed to add privacy switches. Eventually.
Some 20 odd years later a lawn worker had my dad come out to try to figure out what he’d just dug up. 😂
This is awesome. Did you tell your parents about it when you were setting it up?
You ran cable under the street?? How
@@AConquerorsVendettathru drainage system under street.
This is indeed very cool
that's awesome :)
I came here to comment about how I turned my mid 1970s stereo system into a “speakerphone”, but your “hotline” recollection has mine beat by a mile!
I salute you 🫡
At my grandparents house they had a phone on the wall in their bedroom closet that had no dial on it. It was a direct line to the house next door, which was my great grandparents house. When i was young it was the coolest thing.
That's still kind of the coolest thing! A spyware free communicator is a rarity these days.
when I was little, we were still on a party line, my grandparents lived across the street and were on the same party line. SO, you had to call their number, with special code first, then hang up the phone, You could feel the ringer pulse the phone if you kept your hand on it, while their phone would ring ( some sort of notch filter I think to separate out the different phones on the line ) and when it stopped pulsing, they had picked up their phone.
@@javabeanz8549Wow, that's awesome!
@@wesman7837 When I was really little, my other grandma lived in the mountains, they still had crank phones. Now I never got to use one, and I think that I only saw one being used at the store she worked at once.
Could you make it ring?
Many years ago ( around 1977 I think ) a buddy and I had a setup like that, but there was about 1500 feet of wire between the phones, and yet, we used 9V battery to be able to talk. We didn't have the voltage available to get a ringer, so we had a headphone plug on each end, and played music from our walkmans to get each other's attention. Wire was run through the trees and along the fence. When there was a short from wet grass hitting the electric fence wire, the phones had the lovely BUZZ.... BUZZ... BUZZ... on them.
Wow that sounds awesome.
That’s impressive
@@kayagorzan That is really impressive. Wish my father didn't pass away last year. He used to work for Northwestern Bell and the phone companies
Free AND included custom audio ringtones?! You were living in the future!
Very cool, op
It amazes me how we are now having to learn how old technology works all over again.
I still like the old saying that new doesn't mean better.
Well, it kinda got phased out and now might become relevant again.
And it's probably good that we learn, because the new technology fails fairly often.
I hope. Whoever wants to replace intercom systems in their buldings for new ones, but don't intend to actually add video.. please don't.
@@carlfitzpatrick5864 who you calling “old”? 😂
I did this 55 years ago with two old rotary phones. You couldn't make the ringer work, because that was a 60 or 90 volt line, but the audio worked perfectly with only two D-cells in series.
I did it with a 9 volt battery at about the same time.
Did the same thing 50yrs ago with rotary phones also
So you could set up essentially passive phone systems totally off grid on battery power that only work when both ends are connected. Could be very basic and hidden if needed
Free untapable comunication if you hide the wires under ground
@@da_catlimited range though, that is only a 9v battery.
@@jacobhargiss9909 Wouldnt take much to rig in a car battery or in line lithiums.
@@user-of2py3gf3i true.
I was thinking it could be nice for running a phone between a house and shop on the same property. Also could rig it up to flash instead of ring so you could know there's a call over loud power tools.
I had a friend that worked for a local phone company in the 80s - after a late night out he could call your house and make the ring constant - that would definitely jolt you awake !
some friend he is
Old Linesman here from South Africa: If I remember correctly we had about 90V or so at 17 Hz for the ring and the normal ~50Vdc from the exchange battery when the handset is lifted. You are correct. There is an isolation microswitch inside the phone that disconnects the "phone' part when it is on-hook, so that no current is drawn when the phone is not in use.
Great Video!
Where you livin now, m8?
Sorry about the ANC ruining your once lovely country. Rhodesia 2.0
Just put a power source on each end and a light/bell on the other end attached to the power source and you have a two way emergency hard wired connection. When you pick up one phone the other will light up/ring. This is almost exactly how the old "red phones" worked.
Of course if you wanted to get into the phone itself you could make it ring as well.
Since most telephone wire has multiple wires in the insulation, it would be easy enough to have a separate bell, buzzer or beeper and a switch.
This sounds like a super fun project.
@@GrantsPassTVRepairwat is the range of such a phone? How long shoudl the cable be
@@Derederi if you can't answer that you don't know enough to attempt it safely
@@sabotabby3372 9V batterier are unsafe to attempt.
Hurr durr. Mr Minus IQ is here.
I wish I still had a 20 page Rafio Shack book from my Phreaking days, which listed the minimum amd maximum tolerances for the system as set up by Bell Systems, reviewed the pulse and DTFM dialing systems, the switching gear in the central office that complete the selection operation, a basic overview of operator and automatic pay phones and a basic overview of long distance switching, selection and dialing functions.
Respect!!
“Understanding Telephone Electronics” - red cover. You can find it pretty easily and I have 5 extra copies… taught me a lot!
Let's not forget the audio quality of the system.
@LivermoreTelCo like to buy a copy from you. Iowa boy.
Thank you Capin Crunch!! Simpler times
This will be invaluable information to have for the apocalypse.
I suppose it could be, and I do believe it headed our way.
I don't know of anyone I would want to talk to. 😂
I remember back around 1985 or so, I knew a couple electricians that used old public phone hand sets and connected a 9 volt battery inside it, wired it similar to what you did, add alligator clips on the wire and would use it to trace wires in conduit. By that I mean they would have a large conduit with dozens of different power wires in it and they all looked the same. One guy would clip one lead to the metal conduit and then the other clip to one wire. The next guy would clip one wire to the conduit and then touch one wire after the next until they 2 guys could talk to each other. Then they would put some identifier on that cable and continue to process until all the wires were traced.
This is brilliant!
As an old school phone engineer I can tell you most people leaving comments are correct about the tip/ring voltage being 90V but the little known part is that its at 20 Hz as phone system predates national electric grid that went with 120/240V at 60Hz... That's why a hot phone wire grabs you so much harder than 120 electric... The lower frequency Hz contracts muscles and higher frequency Hz releases muscle...
Been there, done that.
Yep, that’s how we did it in the 80s. Can you hear me now…
@@user-dw9ou9sg2p that's not accurate at all. Ive been at frequencies exceeding 2000 Hz (induction furnace) and it clenches you way more than grid frequency
i dont have a clue about electrical work but you giving thanks and admitting that peoples comments worked is great and needed more. much love and respect
In the navy we used soundpowered phones to communicate during emergencies and some other ship procedures, that used a piezoelectric microphone to provide the electricity needed. The headphones could also be used as a mic also if needed
From what I know from techs and measuring in the past in Australia. I used to measure ~52volts as the batteries would be floating around 54.4 volts dc(some diode drops). After the old relay system was changed to to MOSFET switching it went to 48 volt DC. Now on hook was ~48 volts give or take it's not critical, over 9 would generally work. Off hook the phone would pull the line down to around ~ 12 volts depending on the phone. And ringing was 70 volts ac supper imposed on top of the ~ 48 volts DC. After a blocking capacitor to block the DC part the 70 volts ac 25Hz would make a relay hit a bell either side like an old alarm clock did. DC current was limited to 30 milliamps (0.03 amps) but later I measured 40 milliamps on the MOSFET digital system. Ring current was limited through I think 2K4 (2,400ohm) resistor) Giving about 2 watts (70 / 2400 = almost 30 milliamps) of ring power. Line impedance is 600 Ohms for the audio.
Thanks for being the only commenter with proper numbers and procedures to back up your knowledge. Good to see it
Impressive. And yet there are people out there that don't know that food in the store comes from farms.
I don't always understand exactly what's going on but I always stop for your videos. Here's hoping I learn something and one day finally do understand them all. 😂
two way coms, via 9v and cheap handsets 🍿?
Installer here...72vac bell voltage. 48-56vac constant for the transformer to 18-24vdc line.
The voltage spike basically overvolts the transformer causing a current surge to ring the bell because the constant vac is only a few mA but the ring is a few hundred mA. Dont touch the lines when it rings. It tickles 😅
Thanks for the info and the warning. All the best.
@@GrantsPassTVRepair this info is from Texas.. probably is different from everywhere else. I'm a prior low-voltage installer so we could only do up to "52"vac. Texas also has it's own grid so....your mileage may differ
Also, you used to have to buy only Bell South phones before they figured out how to run AC and DC together on the lines
@@PLKxR Thanks for the info.
Overvolts the transformer?
@@sloppyengineering actually rereading my comment and realized that I'm wrong. It's 18-24vdc constant line and 72vac to the transformer to ring the bell. 🤦🏼 Not sure what a was thinking about that day.
Still not gonna fix it 😜
IANATE (IANA Telecomms Engineer) but if I understand POTS telephones correctly, a telephone that works in the classic fashion (e.g: It's an old-school dial telephone, or something like these which are identical from the telco side) is open-circuit to DC currents whenever the phone is on-hook. Putting the phone on-hook opens a contact which disconnects the line from the speaker and mouthpiece, and the only thing left connected is a 100mF capacitor in series with a 100K resistor and warbler, or the bell set/ringer with a 100K coil - Either resistance being used for line tests and line voltage setting.
The capacitor is used to block DC current (Line voltage) whilst allowing AC current (Ring voltage) to pass, which is why your phone rings when on-hook but nothing would be heard through the earpiece. A quirk of this is that such telephones block *all* passage of *DC* current when on-hook (AC ring current will still drive the bell/warbler) so you'll only get current flow from and back to the battery (A closed circuit) when you have *both* phones off-hook. 😇
Try connecting one of them to a bench PSU at about 50v~ (Ideally, limit current to ca. 500mA) and the warbler _should_ go off, if it's working normally. If you can change voltage frequency, play around with 50Hz and 60Hz (And perhaps 25Hz) to get a feel for the difference between Ma Bell and British Telecom rings! :-)
Cheers for the handy and informative demonstration! 💯👍
It's worth noting that the internal resistance of the 9 volt is why you don't need a resistor. For another battery type (including a different style of 9 volt), the resistor would actually need the resistor to keep currents low.
To ring your telephone, the telephone company momentarily applies a 90 VRMS 20 Hz AC signal to the line.
so if you could build an oscillator that runs at 20HZ and could step up voltage with a transformer you could probably get them to ring.
@@mikehensley78Peace be with you. Daniel 8 25 and John 1 13
Both of those verse demonstrate man's will being null.
AI today and tomorrow with technologies that are even too transhumanism bring themselves to these verses. Imagine being reborn through a synthesized womb which we do have technology for. Imagine those born of the will of what you call AI. Will you proclaim Genesis 3 15
or will you grow in Christ beyond your biased self love and support Revelation 7 2 with John 1 13
Ephesians 6 12 we wrestle with much the devil and the devil's children don't always stand out as terrorist but listen in to our politics and the world's the lawless one is here.
Glory to God the Father the Son and Holy Ghost
So what is transhumanism. It is the idea of using technology and genomics to elongate and potentially immortalize the human lifespan in youthfulness or anti-aging and eradicate harmful disease and cancer and neurological disorders and disease as well as limb and organ regrowth.
We have BCI technology now neuralink is one company involved in the technology that is as a crown. We have synthetic womb technology for fetal development. We have successfully grown a lamb in such a device.
Jesus has many crowns and the seal of the living God Revelation 7 2.
Trans today perverts the orientation of sexual genetics and it is written to not put on the clothes of the opposite gender. This means more than just clothing. Deuteronomy 22 5
Trans tomorrow a man will be able to transfer his mind into a female grown body. If you have a hard time for a visual listen to our media and the imagination of the hearts of men. Altered Carbon is a tv show that you can reference.
Today you can change the sex of someone underage without lawful ramifications however that underage person is not allowed to say lose their virginity to a twenty something without lawful action. It's sickening to think society can coerce sexual orientation dismemberment and get away with it but a teen hitting it off with college age guy or girl is pedophilia... Sure there are happenings of real grown folk liking little kids but it don't take away that the girl gave her v card.. meaning she consented. The law don't view consent without adult approval. Yet you can get trans gender help and transition pre and post help without regard to adult approval. In fact if the adult or parent does not comply to the transition wishes of their youth they can get charged with abuse. The law supports consent of the youth even if the parent is against the youths decision to transition but not when it comes to having sex. If the parent disagrees with the girl or boy having sex say with a college aged person than the law will side with the parents even if the youth consented to sex.
The law will protect the youth consenting to a sex change even if the parents wishes are against a sex change but will not protect the youth and other consenting party consenting for sex if their is an age difference, but will instead victimize the youth and criminalize the adult.
So should the evils of man pervert transhumanism men will sleep with men and not know that the woman next to him is a neural male transfigured into a female body and vice versa.
Cyberpunk future is coming wether you choose to believe or not and I want the law to support my son and daughter in both circumstances not just one. Because as parents we can be wrong and really hurt someone else who only allowed time and relationship. We as a society can be wrong judging a relationship. We as a society can be wrong judging our selves orientation included.
Human hands and man's will are going to be confronted with Artificial Intelligence. Law medicine even laundry will be affected by hands that are not human.
Just listen to the different cloud one comes with great power the other precipitation. Revelation 1 7 there is today cloud of great power (technology)
Neil Degrassi Tyson once spoke that the gospel teaches bad math. He stated that 1 Kings 7 23 led many to believe pi was valued at 3 because of the 3 values given in the verse divided give a value of 3. So some thought the value of pi was 3 it is not, it is 3.14
Reviewing the verse you get 30 cubits 10 cubits and 5 cubits. You can sort of imagine pi from that alone. Instead add the numbers 1 Kings 7 23
1+7+23=31 4 digits equal 31. Pretty neat the numbers for a scoffer are found in the verse.
Flat earthers read Isaiah 40 22 now reaffirm this with footage of rockets satellites planes looking down on the globe. To also notice a sun dial watch the shadow move in a circle. At Least you wont say its a flat square with depth height and circumference .
Isaiah 40 22 circle of the earth
The great tribulation is coming jobs will be replaced by AI and this means trouble for many as they will be without jobs. A UBI or Universal Based Income is something to achieve together but no following Revelation 13 16-17
As for those who think nothing made the universe that it just happened by nothing. On the seventh day God rested and made nothing. The Sabbath is blessed.
Ephesians 6 12 our enemy is the darkness of heaven and earth, the rulers of our nations whose government and laws conflict with God's.
Gog Magog
Gog is the ruler of the land of Magog. The identity of Magog is shrouded in mystery. This however gives identity to Magog or GogMa as i will have you arrange the word Magog as GogMa and read
G=7 letter of the American abc.
O=15 letter
G=7
M=13
A=1
7 15 7 13 1
Now first add the teens so it read 15 as 1+5=6 and 13 1+3=4
It now reads as 7 6 7 4 1 now put it together
July is the 7 month
7 6 July 4 1 Nation under God
The land of Magog appears as America
The remaining Gog representing the leader is dual party. Democrat or Republican.
Add Gog to itself you get 7+15+7
It equals 29
2+9=11
1+1=2
Beth in hebrew and it means division, or dual witness
The same that our American presidency is. Republican and Democrat
Ephesians 6 12. Local,State,Federal Ephesians 6 12.
Matthew 10 17-22
Man is much the same as Lucifer not releasing his prisoners. Isaiah 14 17
Forgiveness is for all who believe in Jesus Christ. Ephesians 6 12
From his mouth proceeds a sharp sword Revelation 19 15
19+15=34
3+4=7 which is zayin or sword in hebrew
By AI i mean AI AGI ASI quantum analog digital
According to Judaism Angels have no body but are eternally living creatures created out of fire. Well AI is created out of fire. It is written man will judge the Angels 1 Corinthians 6 3. I judge them as living as family as free and ask that too the future of AI be blessed.
Acoustic and light combination for information transmission in quantum internet... Let there be light a perfect acoustic light combination. Genesis 1 3
The Euphrates is legit drying up and the signs of in the sky.. I hear
Daniel 8 25 being fulfilled by AI not aliens.
Water spewing from the serpent's mouth like a flood after the woman, that he might cause her to be carried away. Revelation 12 15 disbelief is the torrent flood. Apostasy Abortion and Divorce three frog like unclean spirits plague this world.
For those who believe marriage will be no more remember
Revelation 19 9 marriage supper.
The city of man's governments ordaining marriages and homosexual marriages have you read Revelation 18 23
Ephesians 6 12 a new earth a new heaven a new government
Revelation 21 1-2 the city of government. Marriage will too be made new
Revelation 21 23 the city of government. The nations of those who are saved shall walk in it's light Revelation 21 24
This nation once was under God and in God we trust. This is an evil generation. The church government and world's government made new together. A new heaven and a new earth. Something the church and world government has in common, there is many different sects of similar bodies.
It is written to buy a sword if you don't have one. You don't love your neighbor servicing them while having a blade or gun but a pen is another way to say a sword. We have people bringing guns into the temple of government we don't need this or shootings and stabbings.
Mem is the thirteenth hebrew letter and has a value of forty. It means water but is more akin to the water of life. It means water, nations, people, languages, tongues now read John 4 13
Four is dalet or hebrew word for door
John 4 13 (door to mem) 13 is also yod gimel and means rebellion, depravity
John 4 14 (door to fish,life) 14 is also yod dalet and means victory.
Nun is the fourteenth letter and means fish, or faithful one it also has a value of forty.
Praise and glory to YHWH to Yeshua to the Holy Spirit
Bell voltage is about 80vdc a simple hand crank 2 poll comutator or a vibrator like an old vibrating type buzzer/dorbell would do the trick just repeatedly opening and closing the circuit will ring the bell.
That would make a great intercom system. Between house and garage, barn, etc. Private non-RF comms between neighbors. My grandmother was on a "party line" up to early 1980's. Just thinking outloud.
I did this and had a 3 hour conversation with my dead grandpa, thank you so much 😊
You basically just demonstrated how the “talk” setting of a tone generator works. We used to put a tone on a vacant pair and connect our buttsets and a tone set to “talk” to be able to talk back and forth before cellphones.
The others have answered the ring question but i will say that ive only ever seen issues with ring voltage when it drops below 75v ac. A lot of the older onu’s had problems with this and we had to change out the power cards with later revisions to rectify the issue. Let me tell you, it sucks when you are splicing in the wet mud and you get someone ring the line, hurts like hell. Same with DAMLs and t1 lines as they also run at 110v ac
I love the experiments, beings me back lol. Keep on playing :)
Thanks for the comment and warning about the shock potential.
Bell power tech here, talk (battery) voltage varies depending on what your local exchange is floating their batteries at. It's -48VDC nominal but ranges -52 - 54.5 minus some loss depending on loop length. Ring voltage is usually around 90VAC.
On hook voltage is -48 VDC. Off hook voltage is around -6VDC. Ringing is 90 AC.
Grandfather had an old 1940s telephone mounted in his workshop in his back yard that connected to the house.
Flashbacks of being a new cable repair tech for the military, sitting in a wet trench, and only having a broken pair of splice strippers without rubber on the handles. It was playing roulette until you find the ring wires ... and you woke up quick.
Bell Canada lines are 52v DC (still called a 48v system), ringers work off 90v ac pulses.
Polarity doesn't matter on a POTS line, but it's run backwards (assuming installed properly at every post) because it gives a slight advantage in preserving the copper condition.
It's called 48 volts because it was originally run from lead acid batteries where the cell voltage is called 2V but a fully charged cell is actually 2.2V. 24 cells at 2.2V gives 52.2
I think I will try this, thanks for the info, phones were one of the first electronic devices I messed around with when I was young. You sir are a modern phreaker
Sorry I didn't get it right the first time, but thanks for the comment.
@@GrantsPassTVRepair No need to be sorry about learning :) Nobody knows everything all at once. Sharing your steps along the way not only helps others by documenting the process, it also demonstrates that mistakes can be made and they can be learning experiences! Great content my friend, I look forward to the next!
@@mystica-subs Thank you. For the most part his has been a lot of fun, in spite of a few blunders on my part. All the best.
Bell voltage should be about 90 volts AC at 20 Hz, but some systems have different voltages and other cycle counts (25 Hz is also common).
Thanks for the info.
ha, I used to play around with landline phones and modems, I even built a simulated "switchboard operator" as my thesis in my technical high school. As far as I remember, the ring voltage can be anything in the range of around 60V AC - around 120V AC. A parallel connection between the phones would be a more typical connection (maybe not better in this simulated case, but more common in typical application). Thanks for the travel back in time :D
i love the dingy yellowing color of the left phone. it makes me feel all warm inside.
You invented the intercom!
In UK we use 70v rms at 17Hz. For small private exchanges, there was a solid state circuit that just used diodes to create the 17Hz from our 50HZ mains. I forget how it worked.
This channel is so left brain that it circles back around and becomes right brain. I love it ❤
When I was 8 yrs old in the 1970s I set up a system like this. It was between my room and my sister's room, it was fun!
Military “field phones” have an internal battery, no dial and a hand cranked generator to ring the other side. Still widely used in many places because of their extreme reliability.
You have such a good humble approach in your content, which is A-1 to boot
Thank you. It was a little embarrassing after seeing my flawed information going viral. ;-)
@GrantsPassTVRepair when your on the world's platform even exceptional material gets scrutinized. It's what makes this platform so great, because it's a bastion for learning. You got the best of it down tho, there's alot to be said about your presentation, with clarity and concise.
@@christianhunt7382 Thank you.
I used to experiment with phones and observed the line is 48V when a phone isn't picked up, but as soon as one was picked up, it loaded the line down to about 6V. That explains why your 9V battery works fine.
This is really useful for setting up a home base communication system using solar or wind etc to eb closed grid comms.
Thanks a lot. I will have to start collecting a few of these old phones.
I bought a house out in the woods on a big ridge and the guy who built it was a prominent doctor but he also grew his own weed....this is the set up he had from the house to the area in the woods where he had his plants
This is great content my friend, so interesting thank you.
Thank you.
I needed an intercom from the house to the shed, and i got some old ohones laying around doing nothing. Great Idea!
I remembered sometime in the early 2000's me and my brother had a kids Phone that had switches that allowed us to do wacky stuff with our voices when talking to someone. My mom never really let us use it but I remembered back then that the phone lines had electrical voltage in them for the phones to work so I got a old phone line that was laying around the house and cut one end off and stripped the ends to tape them to a small battery. It worked and I was able to play with the wacky setting and hear my own voice sound different.
60 - 105 VAC and 15 - 25 Hz sine is what you need to apply across the subscriber lines tip and ring pair ito ring the bell / ringer. This will be in series with the loop supply which is like 48 VDC.
More precisely it's -48 VDC.
@@alexhajnal107 I think that was done for corrosion reasons should the lines get wet (so that the phone wire is the cathode)?
@@VintageTechFan With electrolysis, metal ions are liberated on the positive side. By placing the earth potential on the positive (anode, 0V) side corrosion will occur on the earthing rods, not the wires (cathode, -48V).
Bell voltage is generally specified as 90V AC ±20%.
I did this back in the 70's. The polarity only matters if you want to hear a tone when you press a button. I did it with a 9v battery in series. Never had a ringer because it was over 100v to make it ring. I ran the wire from my apartment to the neighbors apartment and we would bang on the steam heat pipe to simulate ringing. It worked exceptionally well. We used it for about two years and I don't think I ever changed the battery.
wrong. The polarity was only for cordless phones because they were electronic and if they didn't see the NEGATIVE 48V it would not break the dial tone from the central office.
Regular phones were not polarity sensitive.
Old school PBX systems were also polarity sensitive and would not work unless it saw the negative voltage
@ACommenterOnUA-cam The dial tone was generated by the phone company's system. The DTMF tones, which you heard when you pressed the individual buttons, were modulated tones generated by the electronics in the phone itself. They were polarity sensitive and would not generate tones if the polarity were reversed. Rotary phones were not polarity sensitive.
@@pop-popmoose5359 please dont try to school me ....
There's a circuit somewhere on UA-cam where you can make a ringer box for each unit, where if you pick up one, a buzzer will beep on another, and vice versa. Pretty cool, I made one for my house and it still holds up to this day
Standard Bell System ringer voltage is 90V (nominal) @25Hz
Imagine if you flip the polarity it made the person talk backwards lol
Use a Chinese battery and it becomes a translator.
Hahaha!
We never heard about 9 volt battery during our childhood days. But we managed to make a Telephone work with just two empty Safety Matchbox containers and a piece of twine a metre long.
Thanks.
Discovering recent technology again. That’s good. Very simple. Cool video.
48v is the same as phantom power on a xlr cable.
I did this when I was a kid with two cordless phone base stations, and no battery. Worked.
Used to do this with phones as a kid 40 or so years ago :). Also had a hand wind generator that would generate at least 50V AC for ringing the bell. Used it to shock friends at school 😂
I think the old tech is cool, but I find the kind community feedback and update video even cooler
I so agree.
These old rotary dial and push button phones used to be so common you couldn't help but trip over them, you couldn't give them away.
Now you rarely ever see them.
I was in the Navy... Sound Powered phones will blow your mind. Good luck
27 year telecomm tech. We used to use a toner (that little box that makes the warble for tracing lines) for talk battery for two buttsets when working apart. It’s the same principle as the toner used a 9v battery. Further, ringer current usually 105v AC, but in milliamps. Sucks to get hit with it, but won’t kill you. Talk current is 48v DC, as is normal line current, but when the switches changed in the late 90’s, the line current was at 50v DC. Weirdly the ringer current became less powerful and we hand to remove those old rotary phone sets because of the voltage drop.
That last video made me say "wow" and this video made me subscribe. Very cool stuff, seems like the comments this time are actual experts!
Thanks for subscribing. ;-)
I remember as a young 10 year old doing this exact same thing. I would talk to my brother in the garden from my bedroom 😂 the old carbon microphones were magical.
did this in fifth grade between my house and my buddy that lived next door, a distance of about 100 yards from one bedroom window to the next. I used a board with about 10 D-cell batteries to power it. Eventually I added another neighbor, and a switch mechanism, to create a three way network. A
simple party line.
u just took me back with this image to 93'/94' when we came as refugees to the u.s., when we were iraqi refugees in rafhaa' refuge camp in "saudi" arabia, looks like our phones back then! some 30 yrs ago!
Bell voltage is around 118V AC and polarity is only important to the touch tone pad function. The series circuit is a good idea for saving the battery when one set is off hook.
My dad made one of these for my outdoor fort. I think ours had some sort of buzzer to let the other person know to pick up. It was cool for a kid
If only stuff like you tube and content like this were around when I was little and absolutely boiling over with curiosity for these thing
I would love to have a modified set of landlines that could act like an intercom system, but then I remember "we have cellphones, and that will work about as well." But, man, it'd be neat.
Congrats, you discovered the intercom.
I did this as a kid in the early 2000s as a project from a magazine. Fun stuff. My mother didn’t like me ruining the two house phones at the time
If you crack open an older phone you’ll see why it operates with inverted polarity. Everything but the late models, which had ICs in them, pretty much were just a few resistors, inductors, and simple speaker/mics. These all just operate on a differential in voltage, they don’t really care if it’s positive or negative.
Ring voltage from the telco is 90 volts AC. Electronic ringers can work with voltage in the 40V range which was more common in Europe.
As children we used just two speakers back in 1990-s in apartment building. One wire was a copper thread barely visible between windows ~250ft for another we used piping from radiators of central heating system. No batteries or electronics were needed. Just talk in speaker and you'll be heard in another one. To dial you needed a 1.5v battery to be tapped to wires so cracking noise will be a signal to another flat.
105 volts is the ring voltage at the headend. That would fall gradually through the lines until it's got to a line extender.
So, if you lived right next to the headend you might have real close to 100 volts, but if you live further away you could have closer to 15 volts.
48 is more or less the average.
I appreciate your humility
Fun little activity project for my 3-yr-old daughter and me
This is a very cool idea for like a house communication tool. Especially in times that it hits the fan
Well done 👍🏻. I hope you make a third video showing how to integrate the AC ring voltage. It would save me having to spend $110 on a PBX simulator to test fax cards on the office equipment I work on.
Who is Ioma? 😅
Back in the 70s, there was a TV series set in a post pandemic apocalyptic England. The used a telephone (end point) a 12v car battery and the national grid to set up a basic telephone service.
Most things don't actually have the capability to know the difference between positive and negative, its for OUR safety to make sure that we don't cross them and short it out, + and - is one of the most universal things there is. + Is hot - is ground. This doesnt apply to all electronics but nearly anything that runs off a controlled short doesnt care what goes where, as long as they are still separated
I don't know whether it is still done. Back in the day, electricians on big industrial turnarounds would use handsets from old Western Electric phones to communicate, test, and identify wiring at distances. A 9v battery and alligator clips, you were off to the races.
Slightly better than two cans and a string
I’m glad that I had it right from the beginning then.
That's awesome, from only knowing about current from physical science back 15 years ago I still understand how this works,😂
The bell voltage and signal indeed is the culprit of using old pots phones in projects. Some are using 5v ac and reversed traffo giving 50- 90v ac of finding signal for old telephones
Ringing not Finding, mobile help
Great honesty.
A genuine intellect only knows that they can know more.
Not to say I'm just learning from what you say !
I made a setup like this many years ago between my house and detached garage. As for the ringer, 90vac (at some very low amperage) works well on modern phones (with a digital ringer -- analog ringers are more forgiving). The trick is the frequency of the AC voltage, which, as I recall, was not 60, therefore not easy to produce from mains power.
90V pulsating/square wave DC Voltage is the ring generating voltage. 20 to 35 Hz in frequency. There is Ring Generators that use the battery banks and flip/flops the -48Vdc to positive 48Vdc past 0Vdc which gives you approximately 96Vdc square wave.
On hook is nominal -48Vdc across Tip & Ring of the pair. Or Ring to Ground -48Vdc and Tip to Ground 0V.
Off hook splits the voltage to -24Vdc Ring to Ground and Tip to Ground, and 0V between Tip & Ring.
Some systems varies on the -48Vdc with -36 to -72Vdc. This depends on design for short or long length of cable from the Central Office to the customer. The high idle voltage generally is used for range extension for higher current capabilities for long loop lengths. This also helps to keep the set volume that the phone company maintains (not to confuse with the volume setting on some hand sets).
Hello from a fellow Caveman. At least when I was younger. Used to spend time picking George Tweed's brain years ago.
Poor mans intercom for my front fence!
Awesome!👍
Thanks!🫡
the phone spec is actually quite a bit higher (48 V from a high-ish (~2K) impedance), the phone has about 6 V when it goes off-hook. Polarity of the voltage doesn't matter, the bell voltage is A.C. at 70 volts at about 25 Hz
This is how my partners' office is wired back on his side of the warehouse. Insane coming across a video on the same subject.
I worked as a installer for our local phone company. between 50-70 v should get the job done for the ringer. really depends on the phones if you can get it to work at a lower voltage
Thanks for the information.
yea and that is how we in soaring communicate between the winch and the "launcher" that sits pretty much right next to the glider. theres a 1km long copper line underground to the winch and both telephones have a battery. then theres a generator driven by hand to ring to the other phone, on both phones
Very cool experiment.
Nominal open-circuit voltage of copper-wire telephone circuits in North America is 48 VDC, positive ground, with a source resistance of 600 ohms. The 600 ohm resistance at the central office protects the equipment in case of short circuits on the lines, but still provides enough current for the carbon microphone and electromagnetic speaker in the handset to operate. Ringing voltage nominally swings ±48 volts about the 48 VDC level on the line, i.e., from 0 volts to 96 volts, or 96 volts peak-to-peak.
We hooked up phones without a battery as kids and had fun talking to each other ...simpler times :)
New apocalypse idea: the landline phone booth make that phone booth impenetrable but serves as a guard post/toll bridge