A laptop with a desk phone and a 3D-printed acoustic coupler next to it

Acoustic Coupler Gets You Online Through Any Desk Phone

Up until the mid-1980s, connecting a computer to a phone line was tricky: many phone companies didn’t allow the connection of unlicensed equipment to their network, and even if they did, you might still find yourself blocked by a lack of standardized connectors. A simple workaround for all this was an acoustic coupler, a device that played your modem’s sounds directly into a phone’s receiver without any electrical connection. Modem speeds were slow anyway, so the limited bandwidth inherent in such a system was not much of a problem.

Nowadays it’s easier to find an internet connection than a phone line in many places, but if you’re stuck in an ancient hotel in the middle of nowhere you might just find [GusGorman]’s modern take on the acoustic coupler useful. The basic design is quite simple: it’s a 3D-printed box with two cups that fit a typical phone handset and a space to put a USB speaker and microphone. Thanks to minimodem it’s easy to set up a connection with any other computer equipped with a phone connection.

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Termi2 Is Siri Like It’s 1976

What are your plans for the long weekend? If you don’t have time or don’t want to dive into a new project, why not dust off something left unfinished, or do as Hackaday alum [Cameron Coward] did recently and upgrade an old project with a new brain.

In this case, the project in question is a terminal typewriter — a Texas Instruments Silent 700 Terminal, to be exact — into a sort of late ’70’s version of Siri. The terminal typewriter is a special beast that used an acoustic coupler to send and receive both beeps and boops from distant mainframes. Whereas the first iteration of Termi used a Raspberry Pi Zero W to run a script that queries Wolfram Alpha, [Cameron] decided that between the login requirement, the boot time, and the weird formatting required to get it to work, that there had to be a better way.

Turns out that the better way is to use an ESP32 and read the “serial port”, which is a proprietary port with two serial connections — one for the acoustic coupler, and one for regular serial communication. Our favorite thing about this build, no matter the brain, is that there is a permanent record of all the questions and answers. Be sure to check out the video after the break.

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Acoustic Coupler Pole-Vaults Over China’s Firewall

[agp.cooper]’s son recently went to China, and the biggest complaint was the Great Firewall of China. A VPN is a viable option to get around the Great Firewall of China, but [agp] had a better idea: an acoustic coupler for his son’s iPhone.

Hackaday readers of a recent vintage might remember an old US Robotics modem that plugged into your computer and phone line, allowing you to access MySpace or Geocities. Yes, if someone picked up the phone, your connection would drop. Those of us with just a little more experience under our belts will remember the acoustic coupler modem — a cradle that held a phone handset that connected your computer (indirectly) to the phone line.

With a little bit of CNC work, [agp] quickly routed out a block of plywood that cradled his son’s iPhone. Add in a speaker and a microphone, and that’s an acoustic coupler. There’s not much to it, really. The real challenge is building a modem.

In the late 90s, there were dedicated chipsets for modems, and before that, there was a 74xx-series chip that was a 300-baud modem. [agp] isn’t using anything like that. He’s building a modem with an Arduino. This is a Bell 103A-compatible modem, allowing an iPhone to talk to a remote computer at 300 bits per second. This is a difficult challenge; we’re not able to get 33kbps over a smartphone voice connection simply because of the codecs used. However, with a little bit of work, [agp] managed to build a real modem with an Arduino.

1964 300baud Modem Surfs The Web

[phreakmonkey] got his hands on a great piece of old tech. It’s a 1964 Livermore Data Systems Model A Acoustic Coupler Modem. He recieved it in 1989 and recently decided to see if it would actually work. It took some digging to find a proper D25 adapter and even then the original serial adapter wasn’t working because the oscillator depends on the serial voltage. He dials in and connects at 300baud. Then logs into a remote system and fires up lynx to load Wikipedia. Lucky for [phreakmonkey] they managed to decide on a modulation standard in 1962. It’s still amazing to see this machine working 45 years later. He’d love to hear from you if you’ve used a similar device.

[via Waxy]