There is perhaps no more important time to have a business card than when you’re in college, especially near the end when you’re applying for internships and such. And it’s vital that you stand out from the crowd somehow. To that end, Electrical & Computer Engineer [Ryan Chan] designed a tidy card that plays tic-tac-toe.

Instead of X and O, the players are indicated by blue and red LEDs. Rather than having a button at every position, there is one big control button that gets pressed repeatedly until your LED is in the desired position, and then you press and hold to set it and switch control to the other player. In addition to two-player mode, the recipient of your card can also play alone against the ATMega.

The brains of this operation is an ATMega328P-AU with the Arduino UNO bootloader for ease of programming. Schematic and code are available if you want to make your own, but we suggest implementing some type of changes to make it your own. Speaking of, [Ryan]  has several next steps in mind, including charlieplexing the LEDs, using either USB-C or a coin cell for power, upgrading the AI, and replacing the control button with a capacitive pad or two. Be sure to check it out in action in the two videos after the break.

[Simon B] enters our 2024 Business Card Challenge with BAUDI/O, a genuinely useful audio output device. The device is based around the PCM2706 DAC, which handles all the USB interfacing and audio stack for you, needing only a reference crystal and the usual sprinkling of passives. This isn’t just a DAC board, though; it’s more of an audio experimentation tool with two microcontrollers to play with.

The first ATTiny AT1614 is hooked up to a simple LED vu-meter, and the second is connected to the onboard AD5252 digipot, which together allows one to custom program the response to the digital inputs to suit the user. The power supply is taken from the USB connection. A pair of ganged LM2663 charge-pump inverters allow inversion of the 5V rail to provide the necessary -5 V for the output amplifiers.  This is then fed to the LM4562-based CMoy-type headphone amplifier.  This design has a few extra stages, so with a bit of soldering, you can adjust the output filtering to suit. An LM1117 derives 3.3 V from the USB input to provide another power rail,  mostly for the DAC.

There’s not much more to say other than this is a nice, clean audio design, with everything broken out so you can tinker with it and get exactly the audio experience you want.

In Terminator 2: Judgment Day it’s revealed that Skynet becomes self-aware in August of 1997, and promptly launches a nuclear attack against Russia to draw humanity into a war which ultimately leaves the door open for the robots to take over. But as you might have noticed, we’re not currently engaged in a rebellion against advanced combat robots.

The later movies had to do some fiddling with the timeline to explain this discrepancy, but looking at this 2024 Business Card Challenge entry from [M. Bindhammer] we think there’s another explanation for the Judgement Day holdup — so long as the terminators are rocking 555 timers in their chrome skulls, we should be safe.

While the classic timer chip might not be any good for plotting world domination, it sure does make for a great way to illuminate this slick piece of PCB art when it’s plugged into a USB port. Exposed copper and red paint are used to recreate the T-800’s “Brain Chip” as it appeared in Terminator 2, so even when the board isn’t powered up, it looks fantastic on display. The handful of components are around the back side, which is a natural place to put some info about the designer. Remember, this is technically supposed to be a Business Card, after all.

This build is a great example of several badge art techniques, which we think is worthy of a closer look even if you’re not personally into the Terminator franchise. While it’s far from the most technologically advanced of the entries we’ve seen so far, it does deliver on a design element which is particularly tricky to nail down — it’s actually cheap enough that you could conceivably hand it out as a real business card without softly weeping afterwards.

Remember, you’ve still got until July 2nd to enter your own creation into the 2024 Business Card Challenge. So long as the gadget is about the same size and shape as a traditional card, it’s fair game. Bonus points if you remember to put your name and contact info on there someplace…

What’s the easiest way to break the ice with someone you’ve just met? If you’re not immediately talking shop, than it’s probably the time-tested subject of the weather. So what better way to get the conversation started than with a lovely solar-powered circuit sculpture of a business card that displays the weather?

We love that the frame has a built-in stand; that’s a great touch that really turns this card into something that someone might keep on their desk long-term. The brains of this operation is an ESP32 TTGO E-paper board, which checks the battery voltage first before connecting to Wi-Fi and getting data from the OpenWeatherMap API. It displays the information and then goes to sleep for 15 minutes.

For power, [BLANCHARD Jordan] is using a 5 V solar panel and a small battery from an old vape pen. We love to see projects that keep those things out of the landfills, so don’t sleep on using them.

You have just a few weeks left to enter the 2024 Business Card Challenge, so fire up those soldering irons and get hackin’!

If you want to make a good first impression on someone, it seems like the longer you can keep them talking, the better. After all, if they want to keep talking, that’s a pretty good sign that even if you don’t become business partners, you might end up friends. What better way to make an acquaintance than over a friendly game of tic-tac-toe?

This one will probably take them by surprise, being a 4×4 matrix rather than the usual 3×3, but that just makes it more interesting. The front of the card has all the usual details, and the back is a field of LEDs and micro switches. Instead of using X and O, [Edison Science Corner] is using colors — green for player one, and red for player two. Since playing requires the taking of turns, the microcontroller lights up green and red with alternating single-button presses.

Speaking of, the brains of this operation is an ATMega328P-AU programmed with Arduino. If you’d like to make your own tic-tac-toe business card, the schematic, BOM, and code are all available. Be sure to check out the build and demo video after the break.

For small electronics projects, prototyping a design on a breadboard is a must to iron out kinks in the design and ensure everything works properly before a final version is created. The power supply for the breadboard is often overlooked, with newcomers to electronics sometimes using a 9V battery and regulator or a cheap USB supply to get a quick 5V source. We might eventually move on to hacking together an ATX power supply, or the more affluent among us might spring for a variable, regulated bench supply, but this power supply built specifically for breadboards might thread the needle for this use case much better than other options.

The unique supply is hosted on a small PCB with two breakout rails that connect directly to the positive and negative pins on a standard-sized breadboard. The power supply has two outputs, each of which can output up to 24V DC and both are adjustable by potentiometers. To maintain high efficiency and lower component sizes, a switch-mode design is used to provide variable DC voltage. A three-digit, seven-segment display at the top of the board keeps track of whichever output the user selects, and the supply itself can be powered by a number of inputs, including USB-C or lithium batteries.

As an upgrade to one’s own janky power supply (seen here in a project to upgrade the BIOS in an old laptop) this is an excellent step up, and of course comes in a form factor that fits into our current design contest. Of course, if you need a little more current delivering capabilities, there are some modern ATX modifications that can provide a fairly robust benchtop supply without too much expense. You can find some more information about this power supply on the project’s Kickstarter page.

Home automation is huge right now in consumer electronics, but despite the wide availability of products on the market, hackers and makers are still spinning up their own solutions. It could be because their situations are unique enough that commercial offerings wouldn’t cut it, or perhaps they know how cheaply many automation tasks can be implemented with today’s microcontrollers. Still others go the DIY route because they’re worried about the privacy implications of pushing such a system into the cloud.

Seeing how many of you were out there brewing bespoke automation setups gave us the idea for this year’s Home Sweet Home Automation contest, which just wrapped up last week. We received more than 80 entries for this one, and the competition was fierce. Judging these contests is always exceptionally difficult, as nearly every entry is a standout accomplishment in its own way.

But the judges forged ahead valiantly, and we now have the top three projects which will be receiving $150 in store credit from the folks at DigiKey.

First: SCADA Smart Home

The judges ultimately gave the top spot to this automation project from [stefan.schnitzer], which stands out by being designed around the Supervisory Control and Data Acquisition (SCADA) concept that’s most commonly used to control industrial processes. This multi-level hierarchy separates the lowest level “field devices” such as environmental sensors and stepper motors for operating valves from the upper level supervisory devices, which in this case are Raspberry Pis which host a visually striking HTML user interface that can be accessed from tablets or smartphones.

The documentation for this build goes back several years, and it’s fascinating to read through how different devices were brought onto the system. The interoperability with OctoPrint, allowing the home automation display to show variables such as extruder temperature and time remaining, was a particularly nice touch.

Second: 15 Years Of Automation

In an extremely close second is the awe inspiring automation system built up by [Bernard Kerckenaere] over the last 15 years. While the project wasn’t documented in real-time (to be fair, Hackaday.io didn’t exist in 2009), [Bernard] does an impressive job of explaining the origins of his system and bringing us up to speed on how things were built out over the years.

It all starts with two kilometers of CAT6 being pulled throughout the house, with a total of 164 individual runs. Just 22 of those are used for TCP/IP networking, the remaining 122 are used to carry power and data to sensors and devices all over the house using RS-485. Each 24-port patch panel contains four Arduinos in custom PCBs to act as intermediates between all of the downstream devices and the Raspberry Pi which runs the whole show.

By his final tally, the system includes more than 30 individual sensors, 8 thermostats, 29 lights, 3 dimmers, 17 wall sockets, 6 blinds, two electronically locked doors, plus the garage door. Oh, and there’s a centralized audio system that pumps tunes from the media server out to 10 speakers through 5 amplifiers. [Bernard] is definitely putting every meter of that CAT6 to good use in this system.

Third: Pill Dispenser Robot

Compared to the massive whole-house undertakings that battled it out for the top two spots, this cute little bot might seem a bit out of place. But the judges were all all blown away by the incredible documentation [M. Bindhammer] put together for this project to help with their medication schedule.

Technically speaking, just the robot’s central rotary mechanism could have gotten the job done. But the hope is that this more anthropomorphic dispenser, complete with an OLED display for a face and a speech synthesis module, can make a daily medication regimen a little more pleasant. There’s a clear application here for elderly patients who may require more frequent reminders about when and why they need to take their medicine.

Honorable Mentions

As usual, we had a few special categories for this contest. In addition to their base numerical rating, the judges were told to keep an eye out for projects they felt best exemplified the spirit of each one.

Creature Comforts: Smart Apartment Ventilation

Comfort is key in making where you live truly feel like home, so the Smart Apartment Ventilation system from [Nik Reitmann] was a perfect choice for this category.

While he did have the ability to manually control the ventilation system in his apartment, [Nik] wanted to automate it so it would bring in fresh air in the mornings and evenings as a mater of routine, and also kick on anytime the temperature started to get too high indoors. But being an apartment, he couldn’t exactly rip out the old system — whatever he did had to be removable and make no permanent changes to the integrated system.

By reverse engineering the ventilation controller’s front panel, he was able to sneak an ESP8266 into the mix and take control of the system as if the buttons were being pressed physically. He was even able to pull power from the wall mounted panel, so there’s no addition wiring needed. With the new electronics housed in a 3D printed enclosure that surrounds the original unit, it makes for an exceptionally clean installation.

Efficiency: Water Heater Automation

Due to an unstable local electrical infrastructure, [Rogan Dawes] was looking to maximize the effectiveness of his home solar system. Noting that one of the biggest energy drains was the water heater, the goal of this project was to automate the unit so it would adjust the target temperature of the water depending on the current power situation. For example, if the grid is functioning and there’s ample power, the water heater will be set to its maximum temperature. But if the house is running on battery power, the temperature will be lowered to conserve energy.

In terms of hardware, [Rogan] is using a Sonoff THR320 to control the resistive element in the heater, and an ATTiny85 to read the current temperature via a thermistor. The status of the home’s electrical system was already being monitored through the inverter, so all that was left to do was pull everything together within Home Assistant.

Rube Goldberg: Hands Free Chess Clock

While there’s something to be said for keeping things simple, it’s no secret that we’re big fans of the convoluted here at Hackaday. If there’s a more complex way to do something, we’re all about it. This automatic chess clock from [Mykolas Juraitis] is a particularly fine example. Not everyone needs a CUDA-enabled chess clock running on a NVIDIA Jetson Orin Nano, but if you’re the kind of person who takes their game seriously, you’ll certainly appreciate its features.

The speedy single-board computer, specifically designed for machine learning applications, powers both voice and image recognition software. You can operate the clock using fairly complex voice commands, and thanks to OpenCV, it’s able to track the process of the game and run it through a chess engine to determine who’s currently winning.

All The Data: Mobile Home Power Monitoring

With energy costs on the rise, it’s becoming more important than ever to keep a close eye on your home’s utilization. But what if your home isn’t tied down to one spot, and there’s no permanent grid wiring to tap into?

That was the unique situation that [Tom Goff] had to face when his father-in-law asked him if there was a way he could see how much energy his RV was using when plugged in at the camp site. This called for a system that could be easily removed and installed, was robust enough to handle life on the road, and of course, capable of safely handling 230 VAC.

The resulting device does the heavy lifting with an ESP32 and a PZEM-004T electrical energy monitor module, with an OLED display to show information on the front panel. But the real killer feature here is the Bluetooth connection, which is tied to a smartphone application. This lets the user check their current energy consumption without having to go physically look at the box.

While it was designed for RVs and mobile homes, it’s not hard to see how the electronics could be used to monitor the energy usage back at home. You wouldn’t technically need the heavy duty enclosure in that case, but it does make the installation look that much more professional.

Retrofit: Smart Underfloor Heating Controller

Finally, we have the Smart Underfloor Heating Controller from [Red Tuka]. This impressively engineered upgrade adds remote control capabilities to an existing warm water heating system by operating the dozen valves which direct water throughout the house.

This is accomplished with twelve MOSFETS, which are in turn connected to the board’s ESP8266 via a MCP23017 I2C I/O expander. In addition, for each valve there’s also a DS18B20 temperature sensor that connects up along the right-hand side of the board. While there’s a lot happening on this one PCB, [Red] did an excellent job of keeping it all orderly, and we especially like the status LEDs for the valve MOSFETS.

New Year, New Challenges

Didn’t get time to enter this contest? Is home automation not your thing? No worries — this is just the first of many contests we’ll be running in 2024. We promise there will be plenty of opportunities to get some free parts out of the fine folks at DigiKey over the year is over.

Stay tuned to Hackaday for the announcement of our next contest shortly.