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Build Your Own Rotary-Dial Cell Phone
hwestiii writes "Yet another indicator of how unrepresentative of the main Slashdot crowd I am (meaning 'old') is that, like vinyl records, 8-track tapes, and Pintos, I can remember when rotary dial phones were items of everyday use, and not some object of retro-cool pseudo-nostalgia. Imagine my delight, then at finding this project in which an old rotary phone is turned into a cell phone. To give credit where its due, I originally found it linked from Hack A Day. I know nothing about home-built electronics projects, but this is enough to make me want to learn. If this catches on, imagine what they'll have to do to those 'turn off your cell phone' messages that play in movie theatres."
If, however, on the off chance you find yourself stranded in South English, Iowa, where the only pay phone in town is still rotary, this is how it works.
Pick up the phone and wait for dialtone. Insert a dime. (Yes, this phone still costs a dime!) Now, see the holes arranged on the disc? Find the one corresponding to the digit you want to dial, insert your finger, and rotate the disc clockwise until you hit the stop. Remove your finger. Wait for the dial to rotate back to its original position. Repeat as needed.
While you were dialing, did you hear those clicks? The circuit is actually being interrupted at a rate of 10 times per second. (This will be 20 times in some other countries.) The switching equipment in the central office measures the number of clicks and the time in between them to determine the number you dialed.
For more information, I suggest reading old articles of Phrack.
How am I supposed to fit a pithy, relevant quote into 120 characters?
10 times per what? Only if you're dialing a zero.
;)
As any old phone phreaker knows, one can dial any (land) phone - even today - by clicking the receiver. To dial a three, for example, one clicks the receiver three times (within a second).
If you don't believe me, pick up your house phone and try it. This once was useful information, in the days of rotary phone locks, but now is just more useless trivia cluttering up my brain.
If you're not living on the edge, you're just taking up space!
Clarification: there are two or three clicks to add in addtition to the number, and zero counts as 10. (plus the 2 or 3) So to dial a 7 you'd have to click it like 10 times... but at 10 clicks/second, which could be a little challenging.
I work for the Department of Redundancy Department.
You sure? I used to call people by doing the epileptic thing with the receiver hook, but I never had to add 2 or 3 clicks.
Same here. I used to have to use this little 'hack' on a certain phone I had where the 5 button no longer worked properly... Anytime I needed to dial a number with a five in it, it was "'Damn it!' tap-tap-tap-tap-tap"
At least, it worked this way in 708 land....
On a regular US land line, the incoming signal that sets the phone ringing is 90 Volts peak-to-peak. This voltage more or less drives the coils on the ringer directly. Because it's a genuine electromagnetic affair, it sucks down tons of current -- far more than you're going to get out of a puny cell phone battery running through an inverter.
You're probably better off just playing a sound sample of an old-style ringer.
Schwab
Editor, A1-AAA AmeriCaptions
No-one actually has these anymore. But most people have used them. The rotaries were replaced by keypads and even wireless in-home-proprietary systems in the 90's... anyone older than 20 must have used them. I remember using the rotary throughout the 80's. It's not like this is ancient history. And FYI, the 8-track players... in Finland I have _never_ seen even one. I'm 31. It was all C-cassette and radio, and shitty small japanese Datsuns for the mainstream. The 8-track must be an American-only-thing? I do have A-TRAC by Sony... PS. (the Datsuns were a hit in Finland in late 70's because the japanese pioneered targeting a car for a specific climate and audience.)
'Once scientists, even the dim-witted social scientists, get muzzled, the Western Civilization is finished.' - oldhack
Oddly, they used to make drop-in replacements for those carbon buttons that were more modern, but it's probably getting harder to find them than the genuine thing.
Also, the user interface issue of not knowing whether there was a problem with the call makes the hack much less cool, since much more annoying. Even if it ruined the retro feel some indication should have been given of call status. An unobtrusive LED near the base of the phone would do. For that matter some old office phones had a "message waiting" light that was incandescent, but you wouldn't notice the difference if you dropped a white LED under the dome. That could have flashed a few status messages to let you know why things weren't working as they are supposed to.
Brackets contain world's first nanosig, highly magnified:[.]
Every modern phone I've seen has a little Pulse/Tone switch on it somewhere, usually in the back. (Even portable phones.. not, obviously, cell phones, since they use neither method to send the number.) I always thought this was a curious artifact of an era long gone, but if you really wanted to stick the phone company for $1.50 a month, I suppose you could switch all your phones to 'pulse' and cancel the touch-tone service.
~ Aero
1. Rotary phones were built to last (unlike many digital phones). They can survive a drop from a two story building onto concrete. Just go down, pick it up, plug it in, and it will work.
;-) )
:-)
2. Rotary phones can withstand 300lbs of pressure before they will break or deform.
3.Rotary phones can withstand temperatures of up to 1,000 degrees. This may seem a stretch, but rotary phones have been in buildings which have burnt to the ground and still worked.
4. You do not need to be able to dial a rotary or digital phone. You just need to be able to push the button/hanger on the phone. As the original poster stated, the way in which rotary phones work (not cell phones mind you) is that they disconnect for a short period of time (like a 1/10 of a second) and then reconnect. What you might NOT know is that all digital land lines can be operated as a rotary phone too. So in an emergency, all you need to do is to tap the button/hanger on your phone's base with a slight pause between the dialing of the numbers. It will still connect. (So to call 1-411 would be one click, a slight pause, four clicks, pause, one click, pause, and one click. Try it sometime.) (I used to do this to dial out from the university on phones with a phone lock on them!
5. Digital phones sometimes have a switch on them to switch between rotary mode and digital mode. You can switch it to rotary mode, dial the number (and hear the antiquated clicks), and then switch back to digital mode to handle any of those "Press 1 to do Blah". I discovered this at my mom's house. She had rotary service (way out in the country!) but I'd dial the line, let the roatry part go through and then switch the phone over to digital mode to do things.
6. Digital phones can be dialed by whistling into them. It isn't easy but you can do it if you practice long enough (and are bored enough).
7. One of the last interesting things to know is that if you are ever, ever stranded somewhere with a broken phone and you need help, you can still use the phone line and dial the phone. All you need is to bare some of the wire and you have a telegraph. Hold the two wires together to complete the circuit and then use the two wires just like you would the button/hanger. Take them apart and you break the connection. Hold them together and you've got a connection. Operators are probably not as smart as they used to be about this (since telegraphs are not so common place anymore) but it used to be that you could do the old SOS and they would send someone. However, if you dial 911 using the above method and twist the two wires together afterwards the police will come out to investigate.
Just a bit of FYI stuff.
Someone put a black hole in my pocket and now I'm broke.
Not in the USA. Here 1 pulse = Number 1, through 9, and 10 pulses = Number 0. Some other countries Japan, Korea, and parts of EU use 1 to equal the number 0, and 2 for 1, through 10 for number 9.
I've dialled that way slapping the paddle on a payphone before!
-- You are in a maze of little, twisty passages, all different... --
I have both used an abacus and washed my clothes on a washboard. But I don't feel superior for being older. Instead, I feel ... er, older. Look at all this gray hair! Well, the women like it, so it can't be all bad...
I honestly think that they should teach at least college math students how to use an abacus and a slide rule. The reason is simple--- if you are really trying to learn *math* instead of *arythmatic,* these tools really help you get the feel of how the numbers actually work.
BTW, I am in the under 30 crowd.
I teach people how to use computers. And I *start* by going back to basic concepts. I start by explaining the really technical concepts in plain English like they did in the user manuals from the late 1980's. That way people have a fundamental sense of how things fit together and the computer is not so scary.
Altogether too many things classified as "progress" are actually simply things which make us disconnected from the fundamentals of how things actually work.I do still find important uses for old technology. In particular the old telephones do a great job of explaining the various problems and solutions for two-wire voice traffic and are a whole lot more accessible intellectually than the newer ones.
LedgerSMB: Open source Accounting/ERP
Motorola makes something called a "Cellular Connection". It's a box that plugs into the phone on one side, and provides an RJ-11 POTS (Plain Old Telephone Service) connection on the other. It supports pulse dialing too so there's no need for any PIC firmware debugging.
--
Sigs are a waste of space
TouchTone is NOT digital -- it's an analog dialing system, in fact, the only analog telephone dialing system of which I can think.
Actually, there are three ways to dial digitally with plain old landline telephone service:
*The pulse switch that most phones have
*Tapping very quickly
And you guessed it, since pulse dialing is digital,
*A rotary dial.
Which shows you that progress isn't always digital -- the whole advantage of TouchTone is that it uses sounds within the spectrum of the human voice, meaning that the circuits need no capacity beyond what they already need to pass along DTMF -- which facilitates the menus. This is why cell phones go into a TouchTone mode after the call has been placed by their internal digital dialing systems which are nothing like TouchTone or pulse.
DTMF numbers are made of two separate, simultaneous tones. For instance, the number one is a combination of 1209Hz and 697Hz. Please enlighten as to how you can whistle two tones at once.
For those who did not get it, a "whis" would be the sound of the wheel of the phone rotating and the "k-k-k..." would be the pulse made by the phone. So "Whis" = dude turned the phone wheel "k-k-k-k-k-k-k-k-k" = a nine has been dialed, etc etc...
I'd rather be sailing...