Split Flap Display Tells Us The Word

March 2, 2022 by Bryan Cockfield 12 Comments

LED and LCD displays are a technological marvel. They’ve brought the price of televisions and monitors down to unheard-of levels since the days of CRTs, but this upside arguably comes with an aesthetic cost. When everything is covered in bland computer screens, the world tends to look a lot more monotonous. Not so several decades ago when there were many sharply contrasting ways of displaying information. One example of this different time comes to us by way of this split-flap display that [Erich] has been recreating.

Split-flap displays work by printing letters or numbers on a series of flaps that are attached to a spindle with a stepper motor. Each step of the motor turns the display by one character. They can be noisy and do require a large amount of maintenance compared to modern displays, but have some advantages as well. [Erich]’s version is built out of new acrylic and MDF, and uses an Arduino as the control board. A 3D printer and CNC machine keep the tolerances tight enough for the display to work smoothly and also enable him to expand the display as needed since each character display is fairly modular.

Right now, [Erich]’s display has 20 characters on two different rows and definitely brings us back to the bygone era where displays of this style would have been prominent in airports and train stations. This display uses a lot of the basics from another split flap display that we featured a few years ago but has some improvements. And, if you’d prefer restorations of old displays rather than modern incarnations, we have you covered there as well.

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Pressure Gauge Built In A Vacuum

February 23, 2022 by Bryan Cockfield 6 Comments

Necessity might be the mother of all invention, but we often find that inventions around here are just as often driven by expensive off-the-shelf parts and a lack of willingness to spend top dollar for them. More often than not, we find people building their own tools or parts as if these high prices are a challenge instead of simply shrugging and ordering them from a supplier. The latest in those accepting the challenge of building their own parts is [Advanced Tinkering] who needed a specialty pressure gauge for a vacuum chamber.

In this specific case, the sensor itself is not too highly priced but the controller for it was the deal-breaker, so with a trusty Arduino in hand a custom gauge was fashioned once the sensor was acquired. This one uses an external analog-to-digital converter to interface with the sensor with 16-bit resolution, along with some circuitry to bring the ~8 V output of the sensor down to the 5 V required by the microcontroller. [Advanced Tinkering] wanted a custom live readout as well, so a 3D printed enclosure was built that includes both an LCD readout of the pressure and a screen with a graph of the pressure over time.

For anyone else making sensitive pressure measurements in a vacuum chamber, [Advanced Tinkering] made the project code available on a GitHub page. It’s a great solution to an otherwise overpriced part provided you have the time to build something custom. If you’re looking for something a little less delicate, though, take a look at this no-battery pressure sensor meant to ride along on a bicycle wheel.

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As Fast As A Speeding Bullet

February 14, 2022 by Al Williams 42 Comments

[Electronoobs] built a coil gun and the obvious question is: how fast is the projectile? To answer it, he built a chronograph suitable for timing a bullet. The principle is straightforward. A laser and a light sensor would mark the entry and exit of the projectile over a known distance. As it turns out, there are some issues to resolve.

For one thing, a laser is too narrow and might miss the projectile. The first attempt to rectify this used mirrors, but the loss was too great — we suspect he was using a second surface mirror. The final answer was to use an array of detectors and removed the laser’s collimation lens to cover a wider area.

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A USB interface connected to a Psion Organiser II

Arduino Nano Adds USB Interface To The Psion Organiser II

February 7, 2022 by Robin Kearey 4 Comments

Introduced in 1984, the Psion Organiser series defined the first generation of electronic organizers or PDAs (personal digital assistants). Even though these devices are now over 30 years old, the Psion Organiser scene is alive and well: with new hardware and software is still being developed by enthusiasts the world over.

One of those enthusiasts is [James Stanley], who designed and built a USB interface for the Psion Organiser II. Although a “CommsLink” module providing an RS-232 port was available back in the day, it’s become hard to find, inspiring [James] to design a completely new module based on an Arduino Nano. Hooking it up to the Psion’s data bus was a simple matter of wiring up the eight data lines to the Nano’s GPIO ports. A set of series resistors served to prevent bus contention without having to add glue logic.

Getting the software working was a bit more difficult: the Organiser’s native OPL programming language doesn’t allow the user to directly access the expansion port’s memory address, so [James] had to write a routine in HD6303 machine code to perform the read, then call that routine from OPL to display the result on the screen. Currently, the routine only supports reading data from the Arduino, but extending it to a bidirectional interface should be possible too.

Finally, [James] designed and 3D printed a neat enclosure for the Arduino-USB interface, which makes it look almost as sleek as the original CommsLink module. Perhaps with a bit of further development, this could turn into another way to connect old Psions to the internet. We’ve also featured a new type of Datapak to enhance the Organiser’s memory. Continue reading “Arduino Nano Adds USB Interface To The Psion Organiser II” →

Arduino Activated Automotive Aerodynamic Apparatus Is… (Spoiler Alert!)

February 3, 2022 by Ryan Flowers 8 Comments

Sometimes a great hack is great for no other reason than that it’s fun, and [Michael Rechtin]’s DIY Active Aero Spoiler and Air Brake certainly qualifies as a fun hack. This is a mod designed to live in a world where looks are everything, stickers add horsepower, and a good sound system is more important than good wheel alignment. Why is that? Because like the switch that exists only to activate the mechanism that turns it off, the DIY Active Aero Spoiler and Air Brake seen below is almost completely useless. So to understand its allure, we must understand its inspiration.

For a few decades now, luxury sports car manufacturers have been adding active aerodynamic components to their vehicles. For example, several Porsche models feature adaptive spoilers that adjust to driving conditions. Super cars such as the Bugatti Veyron have spoilers that flip up at high angles during braking to increase drag and reduce braking distance. All of these features are sadly missing from the average two or four door family-car-turned-wannabe-track-fiend. Until now!

[Michael] has created a new active spoiler for every mall-bound muffler-challenged hand me down. The build starts with a CNC cut foam wing which is covered with fiberglass, Bondo (an automotive necessity) and some faux carbon fiber for that go-fast feel. An Arduino, IMU, two servos, and a battery pack detect deceleration and automatically increase the spoiler angle just like the big boys, but without needing any integration into the vehicles systems. Or bolts, for that matter.

It’s unlikely that the braking force is enough to slow down the vehicle though, given that it’s not enough to pop the suction cups holding it to the trunk lid. But does it have the “wow” factor that it was designed to induce? Spoiler Alert: It does!

As it turns out, this isn’t the first adjustable spoiler featured here at Hackaday, and this adjustable spoiler on a car that’s made for actual racing is quite interesting.

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Meowing Box Will Befuddle Your Friends

January 29, 2022 by Lewin Day 11 Comments

If you don’t own a cat, hearing the sound of one meowing from somewhere in the house probably comes as quite a shock. The Cat Prank box built by [Reuben] promises to deliver such hilarity with aplomb.

The idea is simple: hide the Cat Prank box in a cupboard or other space in a friend’s house, and it will meow from its secret location. When found, either the light sensor or motion sensor will trigger the yowling of an angry feline, with hopefully startling effects.

An Arduino Mini is the brains of the operation, paired with an XY-V17B sound module which plays the required animal wailings. There’s also a 433 MHz radio module that lets the prankster trigger meowing via remote control.

Code is available for those wishing to build their own. We’d love to see a mod with a time delay built in, so the device could be hidden and left to start meowing at some later date when the prankster is far away.

Similar work has graced these pages before, like the devilishly fiendish OpenKobold design. Just make sure your friends are receptive to such jokes before you go ahead and invest time and hardware in the prank!

Arduino Meets Quantum Computer

January 19, 2022 by Al Williams 8 Comments

Quantum computers aren’t quite ready for the home lab, but since there are ways to connect to some over the Internet, you can experiment with them more easily than you might think. [Norbert] decided to interface a giant quantum computer to an ordinary Arduino. Why? Well, that isn’t necessarily clear, but then again, why not? He explains basic quantum computing and shows his setup in the video below.

Using the IBM quantum computer and the open source Qiskit makes it relatively easy, with the Python code he’s using on the PC acting as a link between the Arduino and the IBM computer. Of course, you can also use simulation instead of using the real hardware, and for such a simple project it probably doesn’t matter.

Granted, the demo is pretty trivial, lighting an LED with the state of qubit. But the technique might be useful if you wanted to, say, gather information from the real world into a quantum computer. You have to start somewhere.

We’ve looked at quantum computers before. They tell us it is the next big thing, so we want to be prepared. Qiskit is one of several options available today to make it easier.

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