71–80 of 172 posts
European Union recommended emergency number is "112". Because you can morse it with the hook or even by short-circuitin the wires. This is also why the pulse-dialing receiver is operational in most EU countries.
Why not 111? That would have been even easier to manually-pulse dial.
> the battery lasts almost 24 hours It seems like for hobby projects it's really hard to get good battery run times. I wonder why that is. Is is difficult to get everything into the appropriate sleep modes, or are hobbyist parts just that much more power hungry? Commercial feature phones have stand by times measured in weeks.
In other cases, the boards aim to be small instead of complete, so just use a simple LDO to power the device from USB. This uses a ton of power even if the MCU is off, and that's where the battery drain goes. Designs for real products tend to use a DC-DC converter that can be tuned for the desired sleep state.
Finally, the software that hobbyists use is basically designed to be easy, not efficient. You don't write any MCU init code, it just turns all power-sucking peripherals on by default. That way when you go to use them, they work! Accessing MCU-specific features to save power tends to be difficult, because the hobbyist stuff is designed to support every MCU ever designed from decades-old AVR chips to the latest ARM cores. If you're willing to include a bunch of headers and hack around what they do for you, you likely break core things like "read a GPIO pin" or delay_ms(). All in all, it seems unlikely to me that anyone is going to buy an Adafruit board, program it with Arduino, and get a low power device. I tried and failed. Adafruit themselves recommend using an external device to turn the board on and off at a scheduled interval to save power.
(I made an interesting nRF52 clock / temperature sensor with an e-ink display a few months ago. Every minute, the RTC interrupts the MCU to wake up, refresh the display, and send the temperature/humidity data out over BLE. I used Arduino and ... never got the power usage down at all. It lasted for A DAY with a 100mAh Li-ion battery, even with the radio disabled completely. The voltage regulator just burns power while the MCU is asleep waiting for that minute interrupt. As it happens, it is super jarring when the e-ink display refreshes itself every minute, so I ultimately abandoned the product.
Also somewhere in there I realized that using Arduino is a giant waste of time. When you just write your own C code, all of the manufacturer's documentation suddenly becomes applicable, you can use fancy things like an RTOS, and you even get code completion with clangd in your editor. Every time someone mentions microcontrollers I get mad at myself for wasting so many years with hobbyist-grade tools that never worked right. But I digress.)
An interesting exercise is comparing the nRF52 reference design (deep inside a ZIP file from here, https://www.nordicsemi.com/Software-and-Tools/Development-Ki...) with something like Adafruit's nRF52 dev board: https://cdn-learn.adafruit.com/assets/assets/000/052/793/ori... You will notice that Nordic's dev kit has a very complicated power stage, with solder bridges to turn off creature comforts for better power efficiency. Adafruit just has a random linear regulator on there.
European Union recommended emergency number is "112". Because you can morse it with the hook or even by short-circuitin the wires. This is also why the pulse-dialing receiver is operational in most EU countries.
Why not 111? That would have been even easier to manually-pulse dial.
in order to one up this very cool project one would have to: - create a cellphone in a Telephone magneto style from before there were rotaries - train a machine learning algorythm to emulate the behavior of a Switchboard operator so you can have the truely "authentic" old school behavior
European Union recommended emergency number is "112". Because you can morse it with the hook or even by short-circuitin the wires. This is also why the pulse-dialing receiver is operational in most EU countries.
Why not 111? That would have been even easier to manually-pulse dial.
That's why the UK went with 999 as something memorable, but slow to dial.
Earlier quoted context omitted.
Why not 111? That would have been even easier to manually-pulse dial.
In the good old days, they looked at 111 at an emergency number but it was rejected because it was too easy for the digit 1 to be tapped out by in high winds by wires rubbing together. That's why the UK went with 999 as something memorable, but slow to dial.
Sorry. Someone had to.
I use an unmodified rotary phone as my main landline phone. In the UK it would seem that our exchanges still support pulse dialling. The only drawback are menu systems that expect to hear tones, but I get around this with a small app on my mobile phone that just plays DTMF tones. If i want to, i can pick up the receiver and play tones down it to dial a number rather than using the... dial.
You hold your mobile phone up to your rotary phone in order to play the tones? Why not just use the mobile phone to make the call?
Finally there was one long distance service that used speech recognition to dial numbers! It would repeat groups of 3 or 4 digits you spoke, and ask you to verify they were correct with yes or no. If you said no, it would speak each digit back and ask you to verify it: Was the first number 7? ...
The most satisfying way I ever made a free phone call was at the expense of Bell Communications Research (who were up to their ears swimming in as much free phone service as they possibly could give away, so it didn't hurt anyone -- and it was actually with their explicitly spoken consent), and was due to in-band signaling of billing authorization:
Peter Langston (working at Bellcore) created and wrote a classic 1985 Usenix paper about "Eedie & Eddie", whose phone number still rings a bell (in my head at least, since I called it so often):
http://www.langston.com/Papers/
http://www.langston.com/Papers/2332.pdf
>(201) 644-2332 or Eedie & Eddie on the Wire: An Experiment in Music Generation. Peter S Langston. Bell communications Research, Morristown, New Jersey.
>ABSTRACT: At Bell Communications Research a set of programs running on loosely coupled Unix systems equipped with unusual peripherals forms a setting in which ideas about music may be "aired". This paper describes the hardware and software components of a short automated music concert that is available through the public switched telephone network. Three methods of algorithmic music generation are described.
Eedie & Eddie (And The Reggaebots) - Some Velvet Morning (Peter Langston)
https://www.youtube.com/watch?v=1l0Ko1GUiSo
http://www.wfmu.org/365/2003/169.shtml
>At the time I was also running a telephone demo that you could call up to hear samples of music composed for you while-u-wait by the computers in my lab. Most people called the mono telephone number that gave you a monophonic mix of the stereo channels, but you could also call either the left or right channel, or both, one phone on each ear, to get stereo -- this was how I worked from home. The elaborate phone connections were from the telephone switch in Brian Redman's lab.
>When the call would come in, the computers in my lab would start composing the 6 or 7 pieces that were played in the demo, while a voice synthesizer in Brian's lab (Eedie) would accept the call (we paid the long distance on a few collect calls from music researchers in other parts of the world) and introduce the demo, explaining what was going to happen, then the call would be switched over to my lab where another voice synthesizer (Eddie) would take over, introducing each piece as it was played.
>The idea for Eddie's voice came from the overly-happy shipboard computer in the Hitchhiker's Guide to the Galaxy radio serial. In the phone demo Eddie would say something like:
>Hi! This is Eddie! Your computer music phone, FRIEND!
>Oh BOY! You are rilly rilly going to like this music, I can TELL!
>[pause]
>First, I'll just make sure that Peter's computer is working, and then we can share-and-ENJOY!
>This is pretty much the kind of thing that Douglas Adams' computer said, and he was named Eddie, so we used Eddie as an homage. Then, when we wanted the voice-synth that answers the phone in Brian's lab to be female, we considered how, later in the Hitchhiker's Guide, Zaphod Beeblebrox chooses a different personality module for the computer and gets a worried old lady's voice -- "This will all end in tears!" but Adams never gives her a name, so I chose "Edie" as a feminized "Eddie". Unfortunately, the DECtalk voice synthesizer we were using pronounced E-d-i-e just like E-d-d-i-e with a short E vowel "eh" at the start, so we had to spell her name E-e-d-i-e in order to get the long E initial vowel sound.
>Anyway, the little chit-chat between Eedie and Eddie at the beginning of the recording of Some Velvet Morning is typical of the sillier moments in the phone demo introductions, and is included as an attempt to familiarize the listener with their strange accents.
When you called (201) 644-2332, the Dectalk speech synthesizer would answer, say "Hi! This is Eddie! Your computer music phone, FRIEND!", wait a few seconds, then cheerfully and sincerely announce, "Yes, operator. I will accept the charges."
https://en.wikipedia.org/wiki/DECtalk
LGR Oddware: $1,200 DECtalk PC Speech Synthesizer
https://www.youtube.com/watch?v=bPW2S4fZMJY
Then Eddie would launch into his greeting and introduction to the phone tree of cool demos, like singing songs, telling jokes, generating improvisational music with L-systems or Stochastic Binary Subdivision, playing games, reading news summaries and weather reports, etc.
But then some "music researcher in other parts of the world" realized that it was perfect for making operator assisted third party collect phone calls!
Did you ever trick the phone company into cheerfully accepting the charges of a third party phone call? You will!
https://en.wikipedia.org/wiki/Operator_assistance
>A third number call or third party call is an operator assisted telephone call that can be billed to the party other than the calling and called party. The operator calls the third number for the party to accept the charges before the call can proceed.
So you could just dial 0, tell the human operator that you want to call any number you wanted, and charge it to (201) 644-2332. Then they would call that Morristown, New Jersey number for authorization, Eddie would answer, the human would ask "Will you accept the charges for a collect call from ... to ...?", Eddie would then cheerfully announce, "Yes, operator, I will accept the charges!", and the human would say "thank you" and hang up on the loosely coupled network of Unix systems with unusual peripherals at Bell Labs, then connect you through for free to whoever in the world you wanted to talk with, for however long you want to talk, charging the call to Bellcore!
"Share and enjoy!"
On a slightly more practical note, if you want a rotary VoIP desk phone, there's a few models of Grandstream ATAs that understand pulse dialing. They can be registered to Asterisk as normal SIP clients. $20 for the ATA plus $20 for the phone, plus your time to do the software configuration. https://www.ebay.com/itm/Vintage-Black-Rotary-Phone-Telephon...
In the 80's I had a Demon Dialer that stored a whole bunch of phone numbers and could automatically dial them with pulse or touch tone dialing, and switch between them for using alternative long distance services like Sprint, MCI, ITT, etc. Great for getting through to busy modems, radio contests, or just using as an electric phone book, etc. Demon Dialer 176T (the high-end model that stores 176 numbers!) https://www…
Earlier quoted context omitted.
Hand-held DTMF tone generators, for exactly this purpose, were once fairly widespread. A financial institution once sent one to me for navigating its dial-up automated teller system.
Yeah, i looked for something like that to keep next to the phone but couldn't find anything. I was sure they used to be a thing. What you _can_ get however are little kits you wire up inside the pulse dial phone which do an on the fly pulse to DTMF conversion.
European Union recommended emergency number is "112". Because you can morse it with the hook or even by short-circuitin the wires. This is also why the pulse-dialing receiver is operational in most EU countries.
Thank you! Knowing that story is a great mnemonic to remember it, even if you have a push button phone!
1 + 1 = 2
