Author: Al Williams

4333 Articles

Smelly Ultrasound

November 24, 2025 by 26 Comments

We aren’t sure why, but [Lev Chizhov] and some other researchers have found a way to make you smell things by hitting your head with ultrasound. Apparently, your sense of smell lives in your olfactory bulb, and no one, until now, has thought to try zapping it with ultrasound to see what happens.

The bulb is somewhere behind your nose, as you might expect. This is sub-optimal for ultrasound because your nose isn’t flat, and it is full of air. Packing a subject’s nose with gel wasn’t going to win many fans. The answer was to place the transducer on the person’s forehead and shoot down at the bulb. They made a custom headset that let them precisely target areas of the subject’s bulb guided by an MRI.

So far, they have a sample size of two, but they’ve managed to induce the smell of fresh air, garbage, ozone, and burning wood. What would you do with this? Smell-o-vision? A garbage truck VR game? Let us know in the comments. We don’t think this is exactly how the last VR smell gadget we saw worked, but — honestly — we aren’t completely sure.

Retrotechtacular: Computers In Schools? 1979 Says Yes

November 23, 2025 by 28 Comments

The BBC wanted to show everyone how a computer might be used in schools. A program aired in 1979 asks, “Will Computers Revolutionise Education?” There’s vintage hardware and an appearance of PILOT, made for computer instructions.

Using PILOT looks suspiciously like working with a modern chatbot without as much AI noise. The French teacher in the video likes that schoolboys were practicing their French verb conjugation on the computer instead of playing football.

If you want a better look at hardware, around the five-minute mark, you see schoolkids making printed circuit boards, and some truly vintage oscilloscope close-ups. There are plenty of tiny monitors and large, noisy printing terminals.

You have to wonder where the eight-year-olds who learned about computers in the video are today, and what kind of computer they have. They learned binary and the Towers of Hanoi. Their teacher said the kids now knew more about computers than their parents did.

As a future prediction, [James Bellini] did pretty well. Like many forecasters, he almost didn’t go far enough, as we look back almost 50 years. Sure, Prestel didn’t work out as well as they thought, dying in 1994. But he shouldn’t feel bad. Predicting the future is tough. Unless, of course,  you are [Arthur C. Clarke].

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Assistive Radio Tells You What You Can’t See

November 22, 2025 by 2 Comments

We think of radios as audio devices, but for people who are visually impaired, it can be difficult to tell which channel you are listening to at any given time. [Sncarter] has a family member with vision impairment and built a radio to help her. Unfortunately, it was difficult to replicate, so he decided to try again. The result is an FM radio that provides audible status notifications about power and frequency. Check it out in the video below.

This isn’t just some hacked-up commercial radio, but a ground-up design that uses a TEA5767 with an ATMega328 for control. There is an LCD for when someone else might use the radio and an audio amplifier. He built the prototype on a breadboard, but moved the finished product to a PCB.

It isn’t just the electronics and the sound that are assistive. The case has raised bosses to help the user find things like the switch and rotary encoder. The Arduino can speak frequency announcements, although the quality of the voice is something he wants to tackle in the next revision.

These radios on a chip give you many design options. These same ideas can be useful for audiobook players, too.

How To Use That Slide Rule

November 21, 2025 by 30 Comments

You have that slide rule in the back of the closet. Maybe it was from your college days. Maybe it was your Dad’s. Honestly. Do you know how to use it? Really? All the scales? That’s what we thought. [Amen Zwa, Esq.] not only tells you how slide rules came about, but also how to use many of the common scales. You can also see his collection and notes on being a casual slide rule collector and even a few maintenance tips.

The idea behind these computing devices is devilishly simple. It is well known that you can reduce a multiplication operation to addition if you have a table of logarithms. You simply take the log of both operands and add them. Then you do a reverse lookup in the table to get the answer.

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A Paper Caper: The Hole Data

November 20, 2025 by 26 Comments

Since the dawn of computers, we’ve tried different ways to store data. These days, you grab data over the network, but you probably remember using optical disks, floppies, or, more recently, flash drives to load something into your computer. Old computers had to use a variety of methods, such as magnetic tape. But many early computers used some technology that existed from the pre-computer era, like punched cards or, as [Anthony Francis-Jones] shows us, paper tape.

Paper tape was common in TeleType machines and some industrial applications. In fact, as early as 1725, looms could use paper tape, which would eventually lead to punched cards. For computers, there were two common variations that differed in how many holes were punched across the tape: 5 or 8. There was also a small sprocket hole that allowed a gear to move the tape forward through a reader.

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Gilbert Cell Lacks Sullivan

November 20, 2025 by 7 Comments

If you’ve ever used an NE602 or similar IC to build a radio, you might have noticed that the datasheet has a “gilbert cell” mixer. What is that? [Electronics for the Inquisitive Experimenter] explains them in a recent video. The gilbert cell is a multiplier, and multiplying two waveforms will work to mix them together.

At the heart of the gilbert cell is essentially three differential amplifiers that share a common current source. The video shows LTSpice simulations of the circuits as he explains them.

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Rare Filament Makes Weird Benchies

November 20, 2025 by 21 Comments

[Zack], in addition to being a snappy dresser, has a thing for strange 3D printing filament. How strange? Well, in a recent video, he looks at filaments that require 445 C. Even the build plate has to be super hot. He also looks at filament that seems like iron, one that makes you think it is rubber, and a bunch of others.

As you might expect, he’s not using a conventional 3D printer. Although you might be able to get your more conventional printer to handle some of these, especially with some hacking. There is filament with carbon fiber, glass fiber, and more exotic add-ons.

Most of the filaments need special code to get everything working. While you might think you can’t print these engineering filaments, it stands to reason that hobby-grade printers are going to get better over time (as they already have). If the day is coming when folks will be able to print any of these on their out-of-the-box printer, we might as well start researching them now.

If you fancy a drinking game, have a shot every time he changes shots and a double when the Hackaday Prize T-shirt shows up.

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