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Hackaday Links: September 28, 2025

September 28, 2025 by 12 Comments

In today’s “News from the Dystopia” segment, we have a story about fighting retail theft with drones. It centers on Flock Safety, a company that provides surveillance technologies, including UAVs, license plate readers, and gunshot location systems, to law enforcement agencies. Their flagship Aerodome product is a rooftop-mounted dock for a UAV that gets dispatched to a call for service and acts as an eye-in-the-sky until units can arrive on scene. Neat idea and all, and while we can see the utility of such a system in a first responder situation, the company is starting to market a similar system to retailers and other private sector industries as a way to contain costs. The retail use case, which the story stresses has not been deployed yet, would be to launch a drone upon a store’s Asset Protection team noticing someone shoplifting. Flock would then remotely pilot the drone, following the alleged thief back to their lair or hideout and coordinating with law enforcement, who then sweep in to make an arrest.

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Ask Hackaday: With Landline Use In Decline, What’s To Be Done With The Local Loop?

October 12, 2020 by 100 Comments

Walking is great exercise, but it’s good for the mind too: it gives one time to observe and to think. At least that’s what I do on my daily walks, and being me, what I usually observe and think about is the local infrastructure along my route. Recently, I was surprised to see a number of telephone company cabinets lying open next to the sidewalk. Usually when you see an open box, there’s a telephone tech right there, working on the system. But these were wide open and unattended, which I thought was unusual.

I, of course, took the opportunity to check out the contents of these pedestals in detail. Looking at the hundreds of pairs of brightly colored wire all neatly terminated and obviously installed and maintained at great expense, I was left wondering why someone would leave such a valuable asset exposed to the elements. With traditional POTS, or plain old telephone service, on the decline, the world may no longer have much use for the millions of miles of copper cable feeding back to telco central offices (COs) anymore. But there’s got to be something this once-vital infrastructure is still good for, leading me to ask: what’s to be done with the local loop?

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Wood And Carbon Rods Used For This Handsome And Effective Microphone

April 18, 2020 by 20 Comments

Anyone who was active in the phreaking scene or was even the least bit curious about the phone system back in the Ma Bell days no doubt remembers the carbon capsule microphone in the mouthpiece of many telephone handsets. With carbon granules sandwiched between a diaphragm and a metal plate, they were essentially sound-driven variable resistors, and they worked well enough to be the standard microphone for telephony for decades.

In an attempt to reduce complicated practices to their fundamentals, [Simplifier] has undertaken this surprisingly high-fidelity carbon microphone build that hearkens back to the early days of the telephone. It builds on previous work that was more proof of concept but still impressive. In both builds, the diaphragm of the microphone is a thin piece of wood, at first carved from a single block of softwood, then later improved by attaching a thin piece of pine to a red oak frame. The electrical side of the mic has four carbon rods running from the frame to the center of the diaphragm, where they articulate in a carbon block with small divots dug into it. As the diaphragm vibrates, the block exerts more or less pressure on the rods, varying the current across the mic and reproducing the sound. It works quite well, judging by the video after the break.

Congratulations to [Simplifier] for another great build and top-notch craftsmanship. We’ve seen homebrew vacuum tubes, conductive glass, and solar cells from him before, which sort of makes him the high-tech version of Primitive Technology. We’re looking forward to whatever comes next. Continue reading “Wood And Carbon Rods Used For This Handsome And Effective Microphone” →

Retrotechtacular: The Speaking Clock Goes Silent

October 30, 2019 by 28 Comments

It used to be that time was a lot more relative than it is today. With smartphones synced to GPS and network providers’ clocks, we all pretty much have access to an authoritative current time, giving few of us today the wiggle room to explain a tardy arrival at work to an impatient boss by saying our watch is running slow.

Even when that excuse was plausible, it was a bit weak, since almost every telephone system had some sort of time service. The correct time was but a phone call away, announced at first by live operators then later by machines called speaking clocks. Most of these services had been phased out long ago, but one, the speaking clock service in Australia, sounded for the last time at the end of September.

While the decommissioned machine was just another beige box living in a telco rack, the speaking clocks that preceded it were wonderfully complex electromechanical devices, and perfect fodder for a Retrotechtacular deep-dive. Here’s a look at the Australian speaking clock known as “George” and why speaking clocks were once the highest of technology.

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Ask Hackaday: Whatever Happened To Wire Wrapping?

May 4, 2018 by 130 Comments

Back in the 70s when I started getting interested in electronics, tons of magazines catered to the hobbyist market. Popular Electronics was my favorite, and I think I remember the advertisements more than anything, probably because they outnumbered articles by a large margin. Looking back, it seemed like a lot of ad space was sold to companies hawking the tools and materials needed for wire wrapping, which was very popular for prototyping in the days before solderless breadboards were readily available. I remember beauty shots of neat rows of small, gold posts, with stripped wires wrapped evenly around them.

To the budding hobbyist, wire wrapping looked like the skill to have. With a huge selection of posts, terminals, and sockets for ICs and discrete components, as well as a wide range of manual and powered wrapping tools, it seemed like you could build anything with wire wrapping. But fast forward just a decade or so, and wire wrapping seemed to drop out of favor. And today — well, does anyone even wire wrap anymore?

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In-Band Signaling: Coded Squelch Systems

September 13, 2017 by 18 Comments

In the first part of our series on in-band signaling, we discussed one of the most common and easily recognizable forms of audio control, familiar to anyone who has dialed a phone in the last fifty years – dual-tone multifrequency (DTMF) dialing. Our second installment will look at an in-band signaling method that far fewer people have heard, precisely because it was designed to be sub-audible — coded squelch systems for public service and other radio services. Continue reading “In-Band Signaling: Coded Squelch Systems” →

In-Band Signaling: Dual-Tone Multifrequency Dialing

September 5, 2017 by 43 Comments

One late night many decades ago, I chanced upon a technical description of the Touch-Tone system. The book I was reading had an explanation of how each key on a telephone sends a combination of two tones down the wire, and what’s more, it listed the seven audio frequencies needed for the standard 12-key dial pad. I gazed over at my Commodore 64, and inspiration hit — if I can use two of the C64’s three audio channels to generate the dual tones, I bet I can dial the phone! I sprang out of bed and started pecking out a Basic program, and in the wee hours I finally had it generating the recognizable Touch-Tones of my girlfriend’s phone number. I held the mouthpiece of my phone handset up to the speaker of my monitor, started the program, and put the receiver to my ear to hear her phone ringing! Her parents were none too impressed with my accomplishment since it came at 4:00 AM, but I was pretty jazzed about it.

Since that fateful night I’ve always wondered about how the Touch-Tone system worked, and in delving into the topic I discovered that it’s part of a much broader field of control technology called in-band signaling, or the use of audible or sub-audible signals to control an audio or video transmission. It’s pretty interesting stuff, even when it’s not used to inadvertently prank call someone in the middle of the night. Continue reading “In-Band Signaling: Dual-Tone Multifrequency Dialing” →