Day: February 23, 2021

Retro Dreamcast Rhythm Game Controller Built From Scratch

February 23, 2021 by 3 Comments

Pop’n Music is a rhythm game which has had both arcade and home console releases over the years. [Charlie Cole] is a fan of the Dreamcast version, and decided to build his own controller for the game using the new hotness, the Raspberry Pi Pico.

The controller itself is built out of layers of lasercut MDF, along with an acrylic top and cork bottom to make it sit nicely on surfaces. Arcade buttons are installed to play the rhythm game, mimicking the design of the official cabinets seen in arcades. To run the controller, a Pico was pressed into service, with [Charlie] hoping to use the Pico’s PIO hardware to easily and effectively interface with the Dreamcast’s Maple bus. There were a few headaches along the way, and it didn’t quite live up to expectations, but with some clever use of dual cores, [Charlie] was able to get everything up and running.

Often, such vintage gaming hardware can be thin on the ground, so having the skills to build your own can come in handy. We’ve seen rhythm game hardware modded before too, like this repurposed DJ Hero controller. Video after the break.

Capstan Winch Central To This All-Band Adjustable Dipole Antenna

February 23, 2021 by 18 Comments

The perfect antenna is the holy grail of amateur radio. But antenna tuning is a game of inches, and since the optimum length of an antenna depends on the frequency it’s used on, the mere act of spinning the dial means that every antenna design is a compromise. Or perhaps not, if you build this infinitely adjustable capstan-winch dipole antenna.

Dipoles are generally built to resonate around the center frequency of one band, and with allocations ranging almost from “DC to daylight”, hams often end up with a forest of dipoles. [AD0MZ]’s adjustable dipole solves that problem, making the antenna usable from the 80-meter band down to 10 meters. To accomplish this feat it uses something familiar to any sailor: a capstan winch.

The feedpoint of the antenna contains a pair of 3D-printed drums, each wound with a loop of tinned 18-gauge antenna wire attached to some Dacron cord. These make up the adjustable-length elements of the antenna, which are strung through pulleys suspended in trees about 40 meters apart. Inside the feedpoint enclosure are brushes from an electric drill to connect the elements to a 1:1 balun and a stepper motor to run the winch. As the wire pays out of one spool, the Dacron cord is taken up by the other; the same thing happens on the other side of the antenna, resulting in a balanced configuration.

We think this is a really clever design that should make many a ham happy across the bands. We even see how this could be adapted to other antenna configurations, like the end-fed halfwave we recently featured in our “$50 Ham” series.

DodowDIY Is A Homebrew Sleep Aid

February 23, 2021 by 17 Comments

The Dodow is a consumer device that aims to help users sleep, through biofeedback. The idea is to synchronise one’s breathing with the gentle rhythm of the device’s blue LEDs, which helps slow the heartrate and enables the user to more easily drift off to sleep. Noting that the device is essentially a breathing LED and little more, [Daniel Shiffman] set about building his own from scratch.

An ATTiny85 runs the show; no high-powered microcontrollers are necessary here. It’s hooked up to three 5mm blue LEDs, which are slowly ramped up and down to create a smooth, attractive breathing animation. The LEDs are directed upward so that their glow can be seen on the ceiling, allowing the user to lay on their back when getting ready for sleep. It’s all wrapped up in a 3D printed enclosure that is easily modifiable to suit a variety of battery solutions; [Daniel] chose the DL123A for its convenient voltage and battery life in this case. The design is available on Thingiverse for those looking to spin their own.

It’s a neat example of where DIY can really shine – reproducing a somewhat-expensive gadget that is overpriced for its fundamental simplicity. Now when it comes to waking up again, consider building yourself a nifty smart alarm clock.

Ben Krasnow Measures Human Calorie Consumption By Collecting The “Output”

February 23, 2021 by 37 Comments

It’s a bit icky reading between the lines on this one… but it’s a fascinating experiment! In his latest Applied Science video, [Ben Krasnow] tries to measure how efficient the human body is at getting energy from food by accurately measuring what he put in and what comes out of his body.

The jumping off point for this experiment is the calorie count on the back of food packaging. [Ben] touches on “bomb calorimetry” — the process of burning foodstuff in an oxygen-rich environment and measuring the heat given off to establish how much energy was present in the sample. But our bodies are flameless… can we really extract similar amounts of energy as these highly controlled combustion chambers? His solution is to measure his body’s intake by eating nothing but Soylent for a week, then subjects his body’s waste to the bomb calorimetry treatment to calculate how much energy was not absorbed during digestion. (He burned his poop for science, and made fun of some YouTubers at the same time.)

The test apparatus is a cool build — a chunk of pipe with an acrylic/glass laminated window that has a bicycle tire value for pressurization, a pressure gauge, and electrodes to spark the combustion using nichrome wire and cotton string. It’s shown above, burning a Goldfish® cracker but it’s not actually measuring the energy output as this is just a test run. The actual measurements call for the combustion chamber to be submerged in an insulated water bath so that the temperature change can be measured.

Now to the dirty bits. [Ben] collected fecal matter and freeze-dried it to ready it for the calorimeter. His preparation for the experiment included eating nothing but Soylent (a powdered foodstuff) to achieve an input baseline. The problem is that he measures the fecal matter to have about 75% of the calories per gram compared to the Soylent. Thinking on it, that’s not surprising as we know that dung must have a high caloric level — it burns and has been used throughout history as a source of warmth among other things. But the numbers don’t lead to an obvious conclusion and [Ben] doesn’t have the answer on why the measurements came out this way. In the YouTube comments [Bitluni] asks the question that was on our minds: how do you correlate the volume of the input and output? Is comparing 1g of Soylent to 1g of fecal matter a correct equivalency? Let us know what you think the comments below.

The science of poop is one of those 8th-grade giggle topics, but still totally fascinating. Two other examples that poop to mind are our recent sewage maceration infrastructure article and the science of teaching robot vacuums to detect pet waste.

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Plasma Discharges Show You Where The Radiation Is

February 23, 2021 by 11 Comments

Depending on the context of the situation, the staccato clicks or chirps of a Geiger counter can be either comforting or alarming. But each pip is only an abstraction, an aural indication of when a particle or ray of ionizing radiation passed through a detector. Knowing where that happened might be important, too, under the right circumstances.

While this plasma radiation detector is designed more as a demonstration, it does a pretty good job at localizing where ionization events are happening. Designed and built by [Jay Bowles], the detector is actually pretty simple. Since [Jay] is the type of fellow with plenty of spare high-voltage power supplies lying around, he took a 6 kV flyback supply from an old build and used it here. The detector consists of a steel disk underneath a network of fine wires. Perched atop a frame of acrylic and powered by a 9 V battery, the circuit puts high-voltage across the plate and the wires. After a substantial amount of tweaking, [Jay] got it adjusted so that passing alpha particles from a sample of americium-241 left an ionization trail between the conductors, leading to a miniature lightning bolt.

In the video below, the detector sounds very similar to a Geiger counter, but with the added benefit of a built-in light show. We like the way it looks and works, although we’d perhaps advise a little more caution to anyone disassembling a smoke detector. Especially if you’re taking apart Soviet-era smoke alarms — you might get more than you bargained for.

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Paul Taylor Opened The Lines Of Telecommunication For The Hearing-Impaired

February 23, 2021 by 23 Comments

These days, nearly everyone communicates through some kind of keyboard, whether they are texting, emailing, or posting on various internet discussion forums. Talking over the phone is almost outmoded at this point. But only a few decades ago, the telephone was king of real-time communication. It was and still is a great invention, but unfortunately the technology left the hearing and speaking-impaired communities on an island of silence.

Paul and an early TDD. Image via Rochester Institute of Technology

Engineer and professor Paul Taylor was born deaf in 1939, long before cochlear implants or the existence of laws that called for testing and early identification of hearing impairment in infants. At the age of three, his mother sent him by train to St. Louis to live at a boarding school called the Central Institute for the Deaf (CID).

Here, he was outfitted with a primitive hearing aid and learned to read lips, speak, and use American sign language. At the time, this was the standard plan for deaf and hearing-impaired children — to attend such a school for a decade or so and graduate with the social and academic tools they needed to succeed in public high schools and universities.

After college, Paul became an engineer and in his free time, a champion for the deaf community. He was a pioneer of Telecommunications Devices for the Deaf, better known as TDD or TTY equipment in the US. Later in life, he helped write legislation that became part of the 1990 Americans with Disabilities Act.

Paul was diagnosed with Alzheimer’s in 2017 and died in January of 2021 at the age of 81. He always believed that the more access a deaf person had to technology, the better their life would be, and spent much of his life trying to use technology to improve the deaf experience.

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Useful Build Tips For Making LED Panel Frames

February 23, 2021 by 9 Comments

[NotLikeALeafOnTheWind] has created many LED-based display projects, and shares his method for making attractive LED panel frames and mounts. At first glance it may look as though slapping a rectangle of aluminum extrusion around a display is all it takes, there is also the mounting and management of wiring, power supply, and possibly a Raspberry Pi to deal with. The process of building an attractive frame also has a few hidden gotchas that can be avoided with a bit of careful planning.

Magnetic feet on the LED panels makes mounting much easier and more flexible.

Here is one tip that will resonate with some readers: don’t rely on specified dimensions of parts; measure the actual parts yourself. There can be small differences between what a data sheet says to expect, and the dimensions of the actual part in one’s hands. It may not be much, but it can be the difference between an ideal fit, and something that looks like a bit of a hack job.

[NotLikeALeafOnTheWind] provides some basic frame layouts, and suggests using two- or three-channel extrusions to provide a flat bezel around the display edge if desired. Mounting the LED panel itself is done with magnetic feet and providing a length of steel bar to which the display can attach. This can provide a flush mount while avoiding the whole issue of screw-mounting the display panels themselves, or sliding them into channels. For mounting all the other hardware, a piece of DIN rail and some 3D-printed parts takes care of that.

The result looks slick and sturdy, and some of the tips are sure to be useful even if the whole process isn’t applied. We like the way the basic design scales and is flexible about the thickness and size of the LED panels themselves, making it a promising way to accommodate perfectly functional oddball panels that end up in the trash.