How The Bell System Was Built

July 15, 2024 by Al Williams 9 Comments

We’ve often thought that while going to the moon in the 1960s was audacious, it was just the flashiest of many audacious feats attempted and accomplished in the 20th century. Imagine, for a minute, that the phone system didn’t exist today, and you stood up in front of a corporate board and said, “Let’s run copper wire to every home and business in the world.” They’d probably send you for a psychiatric evaluation. Yet we did just that, and, in the United States, that copper wire was because of the Bell system, which [Brian Potter] describes in a recent post.

The Bell company, regardless of many name changes and divisions, was clearly a very important company. [Brian] points out that in 1917, it was the second-largest company in the United States and continued to grow, eventually employing a whopping 1% of the entire U.S. workforce. That’s what happens when you have a monopoly on a product that is subject to wild demand. In 1900, Bell handled 5 million calls a day. By 1925, that number was over 50 million. In 1975, it was just shy of 500 million. If Wester Electric — just one part of Bell — was its own company, it would have been the 12th largest company in the U.S. during the 1970s.

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Retrotechtacular: Rebuilding A Fire-Ravaged Telephone Exchange

January 11, 2024 by Dan Maloney 15 Comments

Those who haven’t experienced the destruction of a house fire should consider themselves lucky. The speed with which fire can erase a lifetime of work — or a life, for that matter — is stunning. And the disruption a fire causes for survivors, who often escape the blaze with only the clothes on their backs, is almost unfathomable. To face the task of rebuilding a life with just a few smoke-damaged and waterlogged possessions while wearing only pajamas and slippers is a devastating proposition.

As bad as a residential fire may be, though, its impact is mercifully limited to the occupants. Infrastructure fires are another thing entirely; the disruption they cause is often felt far beyond the building or facility involved. The film below documents a perfect example of this: the 1975 New York Telephone Exchange fire, which swept through the company’s central office facility at the corner of 2nd Avenue and 13th Street in Manhattan and cut off service to 300 blocks of the East Village and Lower East Side neighborhoods.

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Taking Mechanical Keyboard Sounds To The Next Level

July 13, 2023 by Bryan Cockfield 10 Comments

When it comes to mechanical keyboards, there’s no end to the amount of customization that can be done. The size and layout of the keyboard is the first thing to figure out, and then switches, keycaps, and then a bunch of other customizations inside the keyboard like the mounting plate and whether or not to add foam strips and other sound- and vibration-deadening features. Of course some prefer to go the other direction with it as well, omitting the foam and installing keys with a more noticeable click, and still others go even further than that by building a separate machine to make their keyboard activity as disruptive as it could possibly be.

This started as a joke among [ac2ev] and some coworkers, who were already teasing about the distinct sound of the mechanical keyboard. This machine, based on a Teensy microcontroller, sits between any USB keyboard and its host computer, intercepting keystrokes and using a small solenoid to tap on a block of wood every time a keystroke is detected. There’s also a bell inside that rings when the enter key is pressed, similar to the return carriage notification for typewriters, and as an additional touch an audio amplifier with attached speaker plays the Mario power-up sound whenever the caps lock key is pressed.

[ac2ev] notes that this could be pushed to the extreme by running a much larger solenoid powered by mains electricity, but since this was more of a proof-of-concept demonstration for some coworkers the smaller solenoid was used instead. The source code for the build can be found on the project’s GitHub page and there’s also a video of this machine in action here as well. Be careful with noisy mechanical keyboards, though, as the sounds the keys produce can sometimes be decoded to determine what the user is typing.

Spooky Coffin Bell Spooks Passers By On Halloween

September 21, 2021 by Lewin Day 3 Comments

Being buried alive isn’t fun, we imagine. Fear of it led to the development of various safety coffin ideas in the 18th and 19th centuries, and [Glen Akins] wonderful Halloween prop riffs on that tradition today.

The safety coffin was a simple solution for those afraid that this might happen to them. One concept had a bell which was installed above freshly dug graves with a string extending into the coffin. One who found themselves accidentally buried alive could then pull the string to ring the bell and summon help.

[Glen’s] installation eliminates the coffin and the dead body, and simply mounts a bell on a post. Inside, there’s an ultrasonic rangefinder that detects passers by. When someone walks closely enough to the prop, a microcontroller triggers a servo which rings the bell with a haunting urgency.

It’s a simple build, but appropriately installed with its LED lighting, it really does pop. It would be a wonderful way to add atmosphere and mood to a Hallowe’en party or haunted house. We’ve seen some great Hallowe’en hacks over the years, and some of the best are pumpkins. Video after the break.

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USB Bell Rings In Custom Terminal

September 13, 2020 by Al Williams 13 Comments

Old TeleTypes and even typewriters had bells. Real bells. So that ASCII BEL character is supposed to make an honest to goodness ringing sound. While some modern terminals make a beep from the computer speakers, it isn’t the same. [Tenderlove] must agree, because the turned a Microchip USB to I2C bridge chip into a HID-controlled bell.

The only problem we see is that you have to have a patch to your terminal to ring the bell. We’d love to see some filter for TCP or serial that would catch BEL characters, but on the plus side, it is easy to ring the bell from any sort of application since it responds to normal HID commands.

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Breathtaking Alarm Clock Looks Like It Came From A 1960 Fallout Shelter

August 10, 2020 by Mike Szczys 24 Comments

All the hardcore geeks have alarm clocks where the bell striker is a hard disk read head… or at least they’ll be building them after seeing this. [Senile Data Systems] created an industrial voltage alarm clock out of decade counters that looks like it was unearthed from a fallout shelter (machine translation).

At first glace you might mistake this for a binary clock since it uses a column of LEDs to indicate each digit of 24-hour time. It’s not, as each row corresponds to a pin on the CD4017 decade counters that make up the timekeeping circuit inside.

Thumb~~screw~~ wheel switches at the top of the bulky handheld unit are how the alarm time is set, triggering a bell along the top edge. The clock is driven by the 50 Hz line voltage and [SDS] tried using that AC to drive a solenoid as the striker on the prototype unit but it performed poorly. The use of a hard disk read head turns out to be the perfect striker, as heard in the video after the break. As for triggering from the decade counters, here’s what [SDS] told us about the design:

The switches’ outputs gets ANDed with a 10 Hz signal (on a 60 Hz grid it will become 12 Hz). This drives a slightly beefy transistor which in turn drives an electromagnet to hammer a bell which broke off my bicycle. Yes. This is a digital analog alarm clock. The clock portion is digital but the bell is analog and sounds like Grampa’s old wind up alarm clock.

The build came about when a cache of over 600 industrial LEDs (24 V – 48 V) fell into his lap. This makes the insides of the clock something to behold as point-to-point soldering connects the panel mount lights and all nine logic chips. Add in that transformer for getting the line voltage and we imagine this thing has quite a bit of heft to it.

If you’ve ever had an alarm with a wind-up bell you know there’s no better way to jolt yourself out of a peaceful slumber and into the chaos of the real world. If the gentle tinkle of the hard drive head isn’t enough for you, this fire bell alarm clock will certainly do the trick.

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Retrotechtacular: Mobile Phones 1940s Style

March 13, 2020 by Al Williams 24 Comments

We think of the mobile phone — well, what we would call a cell phone — as something fairly modern. Many of us can still remember when using a ham radio phone patch from your parked car would have people staring and murmuring. But it turns out in the late 1940s, Bell Telephone offered Mobile Telephone Service (MTS). It was expensive and didn’t work as well as what we have now, but it did let you make or receive calls from your automobile. After the break, you can see a promotional film about MTS.

The service rolled out in St. Louis in the middle of 1946. The 80-pound radios went in the trunk with a remote handset wired to the dashboard. At first, there were only 3 channels but later Bell added 29 more to keep up with demand. An operator connected incoming and outbound calls and if three other people were using their mobile phones, you were out of luck.

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