Lego Tank Fires Soccer Ball Cannon

January 15, 2021 by 5 Comments

Back in the 20th century, Lego Technic was a popular toy designed to teach kids about mechanical technology, and be a lot of fun to boot. Motors and pneumatics were available, but by and large you had to move your creations and make the noises yourself. That’s not the case these days, as the [Brick Experiment Channel] demonstrates with this impressive Lego tank.

The drivetrain is straightforward, using standard Lego tank treads with each side given its own motor for easy skid steering. However, the real party piece is the slingshot cannon, which launches Lego soccer balls at 60 km/h. Utilizing several motors, it’s complete with elevation adjustment for accurate ranging, and a 6 round magazine so you can (slowly) prosecute your targets with rounds downrange.

What really makes this build great is the control system, with the tank being controlled by a PS4 controller via Sbrick, a device that lets Lego motors be controlled via Bluetooth. We’d love to build a couple of Lego vehicles and have them blast away at each other. We’ve seen the technology used before for a secret heist robot. Video after the break.

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Civil Defense Disco Ball Rocks Ground Zero

January 15, 2021 by 9 Comments

Old Civil Defense survey meters like the V-715 are interesting conversation starters, but of very little practical use today. These devices were intended to be a sort of litmus test that survivors of a nuclear blast could use to determine when it was safe to venture out of their radiation shelter: if the needle on the meter moves, even when it’s on the most sensitive setting, you should probably go back inside. Since [Hamilton Karl] would (hopefully) never need such an indicator, he decided to have a little fun with this Cold War holdover and turn it into a Disco Containment Unit.

Technical details are a little sparse on this one, but we can infer most of it just from the pictures. In place of the original meter [Hamilton] has mounted a tiny mirrored ball inside of a protective cage, which is spun by a geared motor that’s occupying the space that used to be taken up by the ion chamber.

A handful of Adafruit NeoPixel RGB LEDs, an Arduino Nano, and a few switches to control it all round out the functional aspects of the build, and a new disco-themed trefoil replaces the original Civil Defense logo on the side. The project page mentions there’s a piezo buzzer onboard that performs a stirring rendition of “Stayin’ Alive” by the Bee Gees, but alas there’s no video that shows it in action.

Thanks to the rugged construction and built-in handle of these old survey meters, [Hamilton] can now take the party with him wherever he goes. Not that he can really go anywhere with this whole global pandemic hanging over our heads, but at least he’ll be ready when things start trending towards normal. In a way the device’s functionality has now been reversed from how it originally worked, since the meter going wild will now be an indicator that its safe to come out.

While the V-715 isn’t of much use outside of a post-apocalyptic hellscape, the V-700 is actually a proper Geiger counter that’s still useful for surveying or research. An important distinction to remember if you ever get a chance to snap one of them up at a swap meet or flea market. Whenever we can start having those again, anyway.

ESP32 Soil Monitors Tap Into Ultra-Low Power Mode

January 14, 2021 by 26 Comments

Soil moisture sensors are cheap and easy to interface with, to the point that combining one with an Arduino and blinking an LED when your potted plant is feeling a bit parched is a common beginners project. But what about on the long term? Outside of a simple proof of concept, what would it take to actually read the data from these sensors over the course of weeks or months?

That’s precisely the question [derflob] recently had to answer. The goal was to build a device that could poll multiple soil sensors and push the data wirelessly into Home Assistant. But since it would be outside on the balcony, it needed to run exclusively on battery power. Luckily his chosen platform, the ESP32, has some phenomenal power saving features. You just need to know how to use them. Continue reading “ESP32 Soil Monitors Tap Into Ultra-Low Power Mode” →

Handheld Slayer Exciter Wand Makes For Easy High Voltage Magic

January 13, 2021 by 35 Comments

It’s often said that any sufficiently advanced technology is indistinguishable from magic, and when a DIY device lets you light up fluorescent bulbs with a flick of the wrist, it’s certainly not hard to see why. The latest creation from [Jay Bowles], this high voltage wand is actually a Slayer Exciter coil that’s able to boost the output of a standard 9 V alkaline or rechargeable battery high enough to perform some of the wireless power tricks we usually associate with the more complex Tesla coil.

We really can’t overstate how simple it is to build one of these yourself. Sure you’ll still need to wind the coil, but if you can chuck the 1/2 inch acrylic tube into a electric drill you should be able to make short work of it. Once you’ve wound your secondary coil from 32 gauge magnet wire, you only need a couple turns of common doorbell wire to make up the primary.

Think there must be some complex electronics hiding in the handle? Far from it. All that’s hidden by that faux-leather wrapping is a transistor to do the high-speed switching, an LED functioning as both the power indicator and the circuit’s diode, and a resistor. [Jay] put it all together dead bug style, but you could do it on a scrap of perfboard if you’d like something a little more robust.

Being a big believer in STEM education, [Jay] says the wand was designed to be as kid-friendly as possible so he could gift it to his young niece and nephew. Inspiring the next generation is certainly something we respect around these parts, though we think there’s plenty of adults who wouldn’t have been disappointed if they unwrapped a gadget like this over the holidays.

If you’d like to play around with a Slayer but aren’t into the whole Harry Potter motif, you might be interested in the larger and more capable version [Jay] built earlier in the year.

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Stepping Down Voltage With Reliability

January 13, 2021 by 36 Comments

The availability of inexpensive electronics modules has opened up a world of opportunity for more complex projects to be completed quickly. Rather than designing everything from scratch, ready-made motor modules, regulators, computer vision modules, and control modules all ready to be put to work after arriving at one’s doorstep. Sometimes, though, these inexpensive electronics aren’t all they’re cracked up to be, so [Jan] decided to produce them from scratch instead.

[Jan] is the creator of several robots, and frequently makes use of 3.3V and 5V step down modules, but was not happy with the consistency offered by the prefab modules. The solution to this was to build them from scratch in a way that makes producing a large amount nearly as easy as ordering them. The boards are based around the SY8105 chip, and are built in two batches for the robotics shop based on the two most commonly needed output voltages. With their design they get exactly what they need every time, without worrying about reliability from a random board shop overseas.

The robotics shop is called RoboticsBrno and they have made the schematics available for anyone that wants to build their own. That being said, the design does not make considerations for low noise since it isn’t required for their use case, but if you’d prefer something simple and reliable this will get the job done. It’s also important to understand the limitations of the parts in a build that are built by a third party, although power supplies are a pretty common area to make improvements on.

Dangerous Greeting Cards You Probably Shouldn’t Send Anyone

January 11, 2021 by 25 Comments

Regular paper greeting cards are pricey for what they are, and of course the annoying musical variety are even more so. If you really want to go all out, however, you’ve got to go custom made. That’s what [Xyla] and [Ian] did, though we’d stop short of recommending you build or send these to anyone!

Two variants of the “dangerous cards” were built. One repurposed an electric shocking circuit from a handheld buzzer, tucking it inside a shiny Disney greeting card. Using a switch from a musical greeting card, when opened, the shocking circuit is activated. With the circuit connected to aluminium tape electrodes hidden in the shiny foil design, when the user opens the card, they receive a painful shock. The flamethrowing variant was triggered by the same mechanism, though instead sent power to an electric match, shooting a fireball with flash cotton when the card was opened.

These cards make excellent pranks, though we’d be wary about sending them by mail for obvious reasons. We’ve seen [Xyla’s] work before too, with her glowing kayak a particular highlight. Video after the break.

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Lego Heist Bot Steals Keys

January 9, 2021 by 7 Comments

Breaking and entering is a felony offense, and one that risks the interloper receiving serious bodily harm for the trouble. Sending in a robot instead is an attractive alternative. While we doubt any actual intention to use their creation for evil, [Brick Experiment Channel] have nonetheless built a viable heist bot out of Lego.

The robot in question is actually two, that work together to execute their mission. Once lowered in the house, the scissor lift bot drives into position next to a coffee table. It then lifts its companion bot into position by extending its motor-driven linear actuators. The recovery bot then drives out onto the table, snatches a set of keys with its arm, and returns to the lift bot, before exiting the house. It’s all achieved with the use of the SBrick, a third-party Lego accessory which allows remote control of Lego motors over Bluetooth. A wireless camera also helps out with vision for the platform.

Lego really does make it easy to build quick, functional mechanisms without a whole lot of fuss. We’ve seen it employed in all sorts of ways, like this handy film scanner. Video after the break.

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