Hackaday Prize 2023: Building A Relay ALU

There’s much truth in the advice that, to truly understand something, you need to build it yourself from the ground up. That’s the idea behind [Christian]’s entry for the Re-engineering Education category of the 2023 Hackaday Prize. Built as an educational demonstrator, this is a complete arithmetic-logic unit (ALU) using discrete relays — and not high-density types either — these are the big honking clear-cased kind.

The design is neatly, intentionally, partitioned along functional lines, with four custom PCB designs, each board operating on 4-bits. To handle a byte-length word, boards are simply cascaded, making a total of eight. The register, adder, logic function, and multiplex boards are the heart of the build with an additional two custom boards for visualization (using an Arduino for convenience) and IO forming the interface. After all, a basic CPU is just an ALU and some control around it, the magic is really in the ALU.

The fundamental logical operations operating upon two operands, {A, B} are A, ~A, B, ~B, A or B, A and B, A xor B, can be computed from just four relays per bit. The logic outputs do need to be fed into a 7-to-1 bit selector before being fed to the output register, but that’s the job of a separate board. The adder function is the most basic, simply a pair of half-adders and an OR-gate to handle the chaining of the carry inputs and generate the carry chain output.

3D printed cable runs are a nice touch and make for a slick wiring job to tie it all together.

For a more complete relay-based CPU, you could check out the MERCIA relay computer project, not to mention this wonderfully polished build.


Hackaday Prize 2023: Low Cost Braille Embosser From 3D Printer Parts

The limited availability of texts transcribed to Braille and the required embossing equipment is a challenge world wide, but especially in poorer countries. To alleviate this problem, a team makers from in Cameroon have been developing BrailleRAP, an open source Braille embosser.

BrailleRAP is built built using commonly available 3D printer components, printed parts, and a laser-cut acrylic or wood frame. Paper is fed between a pair of carriages, the bottom one punching dots with a solenoid while the other acts as the anvil. Sheets of paper are fed in one or two at a time with stepper controlled rollers to control the position. At a cost of about $250, it is about a tenth of the price of the cheapest commercial solution, and the team have created excellent documentation so anyone can build it.

BrailleRAP was inspired by BRAIGO, another Hackaday-featured embosser assembled LEGO Mindstorm parts. We also featured another simple, but ingenious handheld embosser for portable use.

Continue reading “Hackaday Prize 2023: Low Cost Braille Embosser From 3D Printer Parts”

Hackaday Prize 2023: This Challenge Makes It So Easy Being Green

This year’s Hackaday Prize is our first nice round number – number ten! We thought it would be great to look back on the history of the Prize and cherry-pick our favorite themes from the past. Last year’s entire theme was sustainable hacking, and we challenged you to come up with ways to generate or save power, keep existing gear out of the landfill, find clever ways to encourage recycling or build devices to monitor the environment and keep communities safer during weather disasters, and you all came through. Now we’re asking you to do it again.

There are hundreds of ways that we can all go a little bit lighter on this planet, and our Green Hacks Challenge encourages you to make them real. Whether you want to focus on clean energy, smarter recycling, preventing waste, or even cleaning up the messes that we leave behind, every drop of oil left unburned or gadget kept out of the landfill helps keep our world running a little cleaner. Here’s your chance to hack for the planet.


One thing we really loved about last year’s Green Hacks was that it encouraged people to think outside the box. For instance, we got some solar power projects as you’d expect, but we also got a few really interesting wind power entries, ranging from the superbly polished 3D Printed Portable Wind Turbine that won the Grand Prize to the experimental kite turbine in Energy Independence While Travelling, to say nothing of the offbeat research project toward making a Moss Microbial Fuel Cell.

Plastic was also in the air last year, as we saw a number of projects to reuse and recycle this abundant element of our waste stream. From a Plastic Scanner that uses simple spectroscopy to determine what type of plastic you’re looking at, to filament recyclers and trash-based 3D printers to make use of shredded plastic chips.

Finally, you all really put the science into citizen science with projects like OpenDendrometer that helps monitor a single tree’s health, and the Crop Water Stress Sensor that does the same for a whole field. Bees didn’t get left out of the data collection party either, with the Beehive Monitoring and Tracking project. And [Andrew Thaler]’s tremendously practical Ocean Sensing for Everyone: The OpenCTD brought the basics of oceanic environmental monitoring down to an affordable level.

Now It’s Your Turn to be Green

If any of the above resonates with your project goals, it’s time to put them into action! Start up a new project over on Hackaday.io, enter it into the Prize, and you’re on your way. Ten finalists will receive $500 and be eligible to win the Grand Prizes ranging from $5,000 to $50,000. But you’ve only got until Tuesday, July 4th to enter, so don’t sleep.

As always, we’d like to thank our sponsors in the Hackaday Prize, Supplyframe and DigiKey, but we’d also like to thank Protolabs for sponsoring the Green Hacks challenge specifically, and for donating a $5,000 manufacturing grant for one finalist. Maybe that could be you?

Hackaday Prize 2023: Scratch Made 8-Bit Educational Computer

To demonstrate the functionality of an 8-bit computer processor at a very basic level,  [Mazen Gomaa] assembled a Homemade 8-Bit Educational Computer using common CMOS logic chips, a handful of prototyping boards, and an impressive number of carefully connected wires. [Mazen] was inspired by Ben Eater’s 8-bit TTL Breadboard Computer but opted to solder the chips and other components onto proto boards instead of using solderless breadboards.

The 8-Bit computer is based on the Simple-As-Possible (SAP) computer architecture described in the book “Digital Computer Electronics” by [Paul Malvino] and [Jerald Brown]. These useful educational examples demonstrate data, computer logic, and even programming in the context of basic electronic components. Tinkering with such simple computers provides a real “zeros and ones” exposure to computation.

[Mazen] added some additional features and functionality to his computer, including an instruction keypad, an address keypad, a dot matrix memory data viewer, a Schottky diode matrix ROM, and a boot loader that initializes the RAM with data stored in ROM. With clock speeds up to 100 Hz, the computer consumes around 300-500 mA of current.

Future plans include expanding the memory and instruction set from the present 128-bit (8×16) RAM, 64-bit (8×8) ROM, and a set of ten instructions.  Already, this project is a great addition to an ever-growing catalog of homemade solderless breadboard computers, LCD snake games, and VGA video cards.

Continue reading “Hackaday Prize 2023: Scratch Made 8-Bit Educational Computer”

Hackaday Prize 2023: Hearing Sirens When Drivers Can’t

[Jan Říha]’s PionEar device is a wonderful entry to the Assistive Tech portion of the 2023 Hackaday Prize. It’s a small unit intended to perch within view of the driver in a vehicle, and it has one job: flash a light whenever a siren is detected. It is intended to provide drivers with a better awareness of emergency vehicles, because they are so often heard well before they are seen, and their presence disrupts the usual flow of the road. [Jan] learned that there was a positive response in the Deaf and hard of hearing communities to a device like this; roads get safer when one has early warning.

Deaf and hard of hearing folks are perfectly capable of driving. After all, not being able to hear is not a barrier to obeying the rules of the road. Even so, for some drivers it can improve awareness of their surroundings, which translates to greater safety. For the hearing impaired, higher frequencies tend to experience the most attenuation, and this can include high-pitched sirens.

The PionEar leverages embedded machine learning to identify sirens, which is a fantastic application of the technology. Machine learning, after all, is a way to solve the kinds of problems that humans are not good at figuring out how to write a program to solve. Singling out the presence of a siren in live environmental audio definitely qualifies.

We also like the clever way that [Jan] embedded an LED light guide into the 3D-printed enclosure: by making a channel and pouring in a small amount of white resin intended for 3D printers. Cure the resin with a UV light, and one is left with an awfully good light guide that doubles as a diffuser. You can see it all in action in a short video, just under the page break.

Continue reading “Hackaday Prize 2023: Hearing Sirens When Drivers Can’t”

DSP PAW Hardware Platform

Hackaday Prize 2023: Learn DSP With The Portable All-in-One Workstation

Learning Digital Signal Processing (DSP) techniques traditionally involves working through a good bit of mathematics and signal theory. To promote a hands-on approach, [Clyne] developed the DSP PAW (Portable All-in-one Workstation). DSP PAW hardware and software provide a complete learning environment for any computer where DSP algorithms can be entered as C++ code through an Arduino-like IDE.

Continue reading “Hackaday Prize 2023: Learn DSP With The Portable All-in-One Workstation”

Hackaday Prize 2023: A DIY Voice-Control Module

If science fiction taught us anything, it’s that voice control was going to be the human-machine interface of the future. [Dennis] has now whipped up a tutorial that lets you add a voice control module to any of your own projects.

The voice control module uses a Raspberry Pi 4 as the brains of the operation, paired with a Seeed Studio ReSpeaker 4-microphone array. The Pi provides a good amount of processing power to crunch through the audio, while the mic array captures high-quality audio from any direction, which is key to reliable performance. Rhasspy is used as the software element, which is responsible for processing audio in a variety of languages to determine what the user is asking for. Based on the voice commands received, Rhasspy can then run just about anything you could possibly require, from sending MQTT smart home commands to running external programs.

If you’ve always dreamed of whipping up your own version of Jarvis from Iron Man, or you just want a non-cloud solution to turn your lights on and off, [Dennis’s] tutorial is a great place to start. Video after the break.

Continue reading “Hackaday Prize 2023: A DIY Voice-Control Module”