Tech In Plain Sight: Hearing Aids

March 26, 2025 by Al Williams 36 Comments

You might think you don’t need a hearing aid, and you might be right. But in general, hearing loss eventually comes to all of us. In fact, you progressively lose hearing every year, which is why kids can have high-pitched ringtones their parents can’t hear.

You’d think hearing aids would be pretty simple, right? After all, we know how to pick up sounds, amplify them, and play them back. But there’s a lot more to it. Hearing aids need to be small, comfortable, have great battery life, and cram a microphone and speaker into a small area. That also can lead to problems with feedback, which can be very uncomfortable for the user. In addition, they need to handle very soft and loud sounds and accommodate devices like telephones.

Although early hearing aids just made sound louder and, possibly, blocked unwanted sound, modern devices will try to increase volume only in certain bands where the user has hearing loss. They may also employ sophisticated methods to block or reduce noise. Continue reading “Tech In Plain Sight: Hearing Aids” →

Tech In Plain Sight: Shopping Cart Locks

February 28, 2025 by Al Williams 48 Comments

Shopping carts are surprisingly expensive. Prices range up to about $300 for a cart, which may seem like a lot, but they have to be pretty rugged and are made to work for decades. Plastic carts are cheaper, but not by much.

And carts have a way of vanishing. We’ve seen estimates that cart theft costs hundreds of millions of dollars worldwide annually. To stem the tide, stores sometimes pay a reward to people to round up carts off the street and return them to the store — it’s cheaper than buying a new one. That led [Elmer Isaacks] to patent a solution to this problem in 1968.

The [Isaacks] system used lots of magnets. A cart leaving the store had a brake that would be armed by running over a magnet. Customers were expected to follow a path surrounded by magnets to prevent the brake from engaging. If you left the track, a rod passing through the wheel locked it.

A third magnet would disarm the brake when you entered the store again. This is clever, but it has several problems. First, you have to insert magnets all over the place. Second, if someone knows how the system works, a simple magnet will hold the brake off no matter what. Continue reading “Tech In Plain Sight: Shopping Cart Locks” →

Tech In Plain Sight: Security Envelopes

January 8, 2025 by Kristina Panos 18 Comments

You probably get a few of these things each week in the mail. And some of them actually do a good job of obscuring the contents inside, even if you hold the envelope up to the light. But have you ever taken the time to appreciate the beauty of security envelope patterns? Yeah, I didn’t think so.

The really interesting thing is just how many different patterns are out there when a dozen or so would probably cover it. But there are so, so many patterns in the world. In my experience, many utilities and higher-end companies create their own security patterns for mailing out statements and the like, so that right there adds up to some unknown abundance.

So, what did people do before security envelopes? When exactly did they come along? And how many patterns are out there? Let’s take a look beneath the flap.

Continue reading “Tech In Plain Sight: Security Envelopes” →

Tech In Plain Sight: Incandescent Bulbs

December 26, 2024 by Al Williams 71 Comments

While they are dying out, you can still find incandescent bulbs. While these were once totally common, they’ve been largely replaced by LEDs and other lighting technology. However, you still see a number of them in special applications or older gear. If you are above a certain age, you might be surprised that youngsters may have never seen a standard incandescent lightbulb. Even so, the new bulbs are compatible with the old ones, so — mechanically, at least — the bulbs don’t look different on the outside.

You might have learned in school that Thomas Edison invented the light bulb, but the truth is much stranger (public domain)

It has been known for a long time that passing a current through a wire creates a glow. The problem is, the wire — the filament — would burn up quickly. The answer would be a combination of the right filament material and using an evacuated bulb to prevent the filament degrading. But it took over a century to get a commercially successful lightbulb.

We were all taught in school that Thomas Edison invented the light bulb, but the truth is much more complicated. You can go back to 1761 when Ebenezer Kinnersley first caused a wire to glow. Of course, wires would quickly burn up in the air. By the early 19th century, limelight was fairly common in theaters. Limelight — also known as the Drummond light — heated a piece of calcium oxide using a gas torch — not electric, but technically incandescence. Ships at sea and forts in the U.S. Civil War used limelights to illuminate targets and, supposedly, to blind enemy troops at night. Check out the video below to see what a limelight looks like.

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Tech In Plain Sight: Tasers Shooting Confetti

October 16, 2024 by Al Williams 41 Comments

One of the standard tropes in science fiction is some kind of device that can render someone unconscious — you know, like a phaser set to stun. We can imagine times when being aggressively knocked out would lead to some grave consequences, but — we admit — it is probably better than getting shot. However, we don’t really have any reliable technology to do that today. However, if you’ve passed a modern-day policeman, you’ve probably noticed the Taser on their belt. While this sounds like a phaser, it really isn’t anything like it. It is essentially a stun gun with a long reach thanks to a wire with a dart on the end that shoots out of the gun-like device and shocks the target at a distance. Civilian Tasers have a 15-foot long wire, while law enforcement can get longer wires. But did you know that modern Tasers also fire confetti?

It sounds crazy, and it isn’t celebratory. The company that makes the Taser — formerly, the Taser company but now Axon — added the feature because of a common complaint law enforcement had with the device. Interestingly, many things that might be used in comitting a crime are well-understood. Ballistics can often identify that a bullet did or did not come from a particular weapon, for example. Blood and DNA on a scene can provide important clues. Even typewriters and computer printers can be identified by variations in their printing. But if you fire a taser, there’s generally little evidence left behind.

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Tech In Plain Sight: Speedometers

August 22, 2024 by Al Williams 29 Comments

In a modern car, your speedometer might look analog, but it is almost certainly digital and driven by the computer that has to monitor all sorts of things anyway. But how did they work before your car was a rolling computer complex? The electronic speedometer has been around for well over a century and, when you think about it, qualifies as a technlogical marvel.

If you already know how they work, this isn’t a fair question. But if you don’t, think about this. Your dashboard has a cable running into it. The inner part of the cable spins at some rate, which is related to either the car’s transmission or a wheel sensor. How do you make a needle deflect based on the speed?

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Tech In Plain Sight: Escalators

January 29, 2024 by Al Williams 36 Comments

If you are designing a building and need to move many people up or down, you probably will at least consider an escalator. In fact, if you visit most large airports these days, they even use a similar system to move people without changing their altitude. We aren’t sure why the name “slidewalk” never caught on, but they have a similar mechanism to an escalator. Like most things, we don’t think much about them until they don’t work. But they’ve been around a long time and are great examples of simple technology we use so often that it has become invisible.

Of course, there’s always the elevator. However, the elevator can only service one floor at a time, and everyone else has to wait. Plus, a broken elevator is useless, while a broken escalator is — for most failures — just stairs.

Continue reading “Tech In Plain Sight: Escalators” →