Arduino Traffic Light Sings The Song Of Its People

August 7, 2019 by Tom Nardi 29 Comments

Getting an old traffic light and wiring it up to do its thing inside your house isn’t exactly a new trick; it’s so common that it wouldn’t normally pass muster for these hallowed pages. Even using one up to show the real-time status of your build or system resource utilization would be pushing it at this point. To get our attention, your traffic light is going to need to have a unique hook.

So how did [Ronald Diaz] manage to get his project to stand out from the rest? Interestingly enough, it’s nothing you can see. His traffic light doesn’t just look the part, it also sounds like the real thing. With far more effort and attention to detail than you’d probably expect, he’s made it so his Australian pedestrian traffic light correctly mimics the complex chirping of the original.

Working from a video of the traffic light on YouTube, [Ronald] was able to extract and isolate the tones he was after. Performing spectral analysis on the audio sample, he was able to figure out the frequency and durations of the eleven individual tones which make up the complete pattern. From the 973 Hz tone that only lasts 25 ms to the continuous 500 Hz “woodpecker”, every element of the sound was meticulously recreated in his Arduino code.

The Arduino Pro Mini used to control the traffic light is not only responsible for playing the tones through a piezo speaker, but as you might expect, for firing off the relays which ultimately control the red and green lamps. With everything carefully orchestrated, [Ronald] can now get that authentic Australian side-of-the-road experience without having to leave the comfort of his own home.

If you’d rather your in-home traffic light be more useful than realistic, we’ve got plenty of prior art for you to check out. This traffic light that tells you how the value of Bitcoin is trending is a great example. Or maybe this one that can tell you if the Internet is down.

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Sniffed Transformer Puts Wired Doorbell Online

August 6, 2019 by Tom Nardi 30 Comments

There’s certainly no shortage of “smart” gadgets out there that will provide you with a notification, or even a live audiovisual stream, whenever somebody is at your door. But as we’ve seen countless times before, not everyone is thrilled with the terms that most of these products operate under. Getting a notification on your phone when the pizza guy shows up shouldn’t require an email address, credit card number, or DNA sample.

For [Nick Touran], half the work was already done. There was already a traditional wired doorbell in his home, he just had to come up with a minimally invasive way to link it with Home Assistant. He reasoned that he could tap into the low-voltage side of the doorbell transformer and watch for the telltale fluctuations that would indicate the bell was doing its thing. The ESP8266 has an ADC to measure voltage and WiFi to connect to Home Assistant, so it seemed like the perfect bridge between old and new.

Of course, as with any worthwhile project, it ended up being a bit more complicated. Wired doorbells generally operate on 16-24 VAC, and [Nick] knew if he tried to put his Wemos D1 across the line he’d release the critical Magic Smoke. What he needed was a voltage divider circuit that would take low-voltage AC and drop it to an even lower DC voltage that the microcontroller could cope with.

The simple circuit [Nick] comes up with cuts the voltage way down and removes the negative component completely. So what was originally 18.75 VAC turned into a series of 60 Hz blips at 2.4 VDC; perfect for feeding into a microcontroller ADC. With a baseline to work from, he could then write some code that would watch for variations in this signal to determine when the bell was ringing.

Or at least, that was the idea. While the setup worked well enough on the bench, its performance in the real-world left something to be desired. If his house guest had a heavy hand, it worked great. But a quick tap of the doorbell button would tend to go undetected. After investigating the issue, [Nick] found that he needed to use some software trickery to ensure the ESP8266 was able to keep up with the speedy signal. Once he was able to reliably detect short and long button presses, the rest was just a simple matter of sending an MQTT message to his automation system.

Compared to the hoops we’ve seen other hackers have to jump through to smarten up their doorbells, we think [Nick] got off fairly easy. This project is also an excellent example of how learning about circuit design and passive components can still come in handy in the Arduino Era.

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Hold 3500 Volts Up To Your Eye

August 6, 2019 by Bryan Cockfield 15 Comments

Old military equipment can sometimes be found in places like flea markets and eBay for pennies, often because people don’t always know what they have. While [tsbrownie] knew exactly what he was getting when he ordered this mystery device, we’re not sure we could say the same thing if we stumbled upon it ourselves. What looks like a vacuum tube of some sort turns out to be an infrared sensor from an old submarine periscope that was repurposed as a night vision device. (Video, embedded below.)

Of course, getting a tube like this to work requires high voltage. This one specifically needs 3500V in order to work properly, but this was taken care of with a small circuit housed in a PVC-like enclosure. The enclosure houses the tube in the center, with an eye piece at one end and a camera lens at the other, attached presumably by a 3D-printed mount. The electronics are housed in the “grip” and the whole thing looks like a small sightglass with a handle. Once powered up, the device is able to show a classic green night vision scene.

Old analog equipment like this is pretty rare, as are people with the expertise to find these devices and get them working again in some capacity. This is a great video for anyone with an interest in tubes, old military gear, or even if you already built a more modern night vision system a while back.

Thanks to [Zzp100] for the tip!

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Cat Feeder Adds Metrics To Meow Mix

August 5, 2019 by Kristina Panos 16 Comments

If there’s one thing any cat will work for, it’s food. Usually, this just consists of meowing and/or standing on your chest until you give up the goods. [DynamicallyInvokable] has a beautiful cat, Emma, who meows loudly for food at obscene hours of the morning. As she ages, it’s getting harder and more important to control her weight. Clearly, it was time to build the ultimate automatic cat feeder—one that allows him to get lazy while at the same time getting smart about Emma’s weight.

After a year and a half of work, the feeder is complete. Not only does it deliver the goods several times a day, it sends a heap of data to the cloud about Emma’s eating habits. There’s a scale built into the platform, and another in the food bowl. Together, they provide metrics galore that get automatically uploaded to AWS. Everything is controlled with an ESP32 Arduino, including a rainbow of WS2812s that chases its tail around the base of the feeder. The faster it goes, the closer it is to feeding time.

The best part about this unique feeder is that nearly every piece is 3D printed, including the gears. Be sure to check out the build gallery, where you can watch it come together piece by piece. Oh, and claw your way past the break to see Emma get fed.

Emma doesn’t have to worry about sharing her food. If she did, maybe [DynamicallyInvokable] could use facial recognition to meet the needs of multiple cats.

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Dice Reader Brings Tech To Your Craps Game… Or, Ya Know, D&D

August 4, 2019 by Mike Szczys 5 Comments

There are truisms about dice that you’ve probably already heard: if you have just one of them it’s called a “die”, opposite faces of each die always add up to seven, and those dots that you’re adding together are known as “pips”. But what about the infrared properties of those pips? It turns out they reflect less IR than the white body of the die and that trait can be used to build an automatic die reader.

Great projects have a way of bubbling to the surface. The proof of concept comes from way back in 2009, and while the source blog is now defunct, it’s thankfully been preserved by the Internet Archive. In recreating the project based on that barebones description, [Calvin] reached for a set of five IR transmitter/receiver pairs. Take a close look and you’ll see each transmitter is hidden under its partnered receiver. The light shines up through the receiver and the presence of the pip is detected by measuring how much of it bounces back.

This board is only the sensor portion of the design. A 595 shift register provides the ability to control which IR pair is powered, plus five more signals heading out to the analog pins of an Arduino Uno to monitor how much light is being detected by the receivers. Hey, that’s another interesting fact about dice, you only need to read five different pips to establish the value shown!

We wish there were a demo video showing this in action, but alas we couldn’t find one. We were amused to hear [Calvin] mentioned this was a sorting assignment at University and the team didn’t want to build yet another candy sorter. Look, we love an epic M&M sorter just as much as the next electronic geek, but it’s pretty hard to one-up this dice-based random number generator which rolls 1.3 million times each day.

Driving A Big RC Car On The Ceiling

July 30, 2019 by Lewin Day 6 Comments

RC cars are a great way to have fun hooning around. There’s plenty of laughs to be had racing your friends in the local grocery store carpark, ideally after hours. [Ivan Miranda] wanted to go in a different direction, however – and that direction was up. (Video embedded after the break.)

There are existing toys that can pull off a wall-riding feat, but they’re normally on a fairly small scale. [Ivan] wanted to go big, and so outfitted some seriously powerful brushless fans on to his 1/8th Rattler buggy from Hobbyking. After initial failure, a smaller scale model was successfully built and tested, before it was realised the full-sized build had the propellers on backwards.

With this oversight fixed, the car was able to drive on the ceiling, albeit in the limited space between the roof beams. It was somewhat less viable on the wall, struggling to stay stuck and having issues with suspension flex.

Overall, it’s a great application of mass brushless power to fight gravity – the same principle behind the multirotors we all love so much. [Ivan]’s put the same trick to use for getting around on a skateboard, too. Video after the break.

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Dreamcast Gets A Plug-n-Play Hard Drive Mod

July 29, 2019 by Lewin Day 22 Comments

The Dreamcast was a proud moment for Sega, at least initially, being the first console to launch of a new generation. Unfortunately this didn’t translate into massive sales, and the plug was pulled far earlier than expected. The console retains a dedicated fanbase to this day however, who continue to tinker with the hardware. [DreamcastChannel] is one of them, and put together a nifty plug-and-play hard drive mod.

The mod is based on earlier work, which consisted of manually soldering the 44 lines of an IDE cable on to the main Dreamcast motherboard. This allowed an IDE hard drive to be neatly mounted inside the shell, but [DreamcastChannel] knew it was possible to do better.

Starting from scratch, the GDROM optical drive assembly is gutted, leaving just its metal case and PCB. The IDE cable for the hard disk is then soldered to the pads on the PCB. A 3D printed mount is used to fix the hard drive to the metal case. This allows the entire assembly to slot neatly into the Dreamcast, using the GDROM’s original connector.

It’s a hack that makes putting a hard drive into the Dreamcast neat and tidy. Combined with a hacked BIOS and Dreamshell, it makes playing backup games a breeze. We’ve seen plenty of Dreamcast hacks before, too – the VMU is often a key candidate for attention. Video after the break.

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