Speed-Test Your Toys with Die-Cast Drag Strip

I’m sure many of us remember building toy car race tracks as kids, racing the cars, and then arguing over which car came in first and who cheated because they let go of their car too soon. Ah, good times. [Phil] wanted to create a drag strip race track for his son to introduce him to die-cast cars. The only commercial drag strip [Phil] could find didn’t have an electronic start gate or a timer, so he created his own with the help of an Arduino, a servo, and some light dependent resistors.

The Arduino controls everything, the button input, the lightrace2 sensor input, and the servo. A button press tells the Arduino to start the race by pulling the start gate down and starting the timer. When the light sensor is covered, the timer for that lane stops. The time is shown for each lane using a different colored 4-digit 7-segment LED.

There were a couple of problems that had to be solved. The servo launching the cars was pulling too much power when activated so that the IR LEDs used at the finish line would dim enough to trigger before the race had even begun! [Phil]’s article goes over these issues and his design ideas as he built the track.

It’s a simple build that should provide hours of fun for [Phil]’s son and his friends over the years and will hopefully put to rest any arguments over who won. There are lots of photos in [Phil]’s article, as well as several videos showing off how things work and at the end of the article, he includes the code he used to control everything. This would be a great surprise for any nieces and nephews coming to visit over the holidays — you might want to wait for final assembly and include them in the fun!

If you like these kind of projects, we’ve seen a similar Hot Wheels timing system, and a different kind of race track based on a turntable system.

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Smartphone Will Destroy You at Air Hockey

Most of us carry a spectacularly powerful computer in our pocket, which we rarely use for much more than web browsing, social media, and maybe the occasional phone call. Our mobile phones are technological miracles, but their potential sometimes seems wasted.

It’s always a pleasure to see something that makes use of a mobile phone to drive some nuts-and-bolts hardware. [Jose Julio]’s project does just that, using the phone as the brains behind a robotic air hockey table.

Readers with long memories will remember previous air hockey tables from [Jose], using 3D printer components controlled by an Arduino Mega with a webcam suspended above the field of play. This version transfers camera, machine vision, and game strategy to an Android app, leaving the Arduino to control the hardware under wireless network command from above.

The result you can see in the video below the break is an extremely fast-paced game, with the robot looking unbeatable. If you want to build your own there are full instructions and code on GitHub, or if you follow the link from the page linked above, he sells the project as a kit.

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LEGO Strain Wave Gear is Easy on the Eyes

We are continually amazed by the things people do with LEGO and Technics, especially those that require incredible engineering skill. There’s an entire community based around building Great Ball Contraptions, which are LEGO Rube Goldberg machines that move tiny basketballs and soccer balls from one place to another. Except for a few rules about the input and output, the GBC horizons are boundless.

Famed GBC creator [Akiyuki] recently built a GBC module that’s designed to show the movement of strain wave gear systems. These types of gear systems are used in industrial applications where precision is vital. Strain wave gears are capable of reducing gear ratios in a small footprint.

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Laser Cut LEGO in MDF

It’s hard not to be a fan of LEGO. The humble plastic bricks from Denmark enabled many a young engineer to bring their architectural and mechanical fantasies to life. But one limitation was that you were stuck using the bricks LEGO designed. Thankfully, [John Sokol] has come up with a way to laser cut his own LEGO-compatible bricks, and provided the tools so you can do the same.

After hacking an OpenSCAD script to generate just the top pins of the block, [John] exported an SVG into Inkscape so that he could scale the pins properly before exporting a final PNG for the lasercutter. Using RDWorks, [John] was able to find an engraving setting that worked well with dry-erase whiteboard MDF — an unusual material for a brick, but functional nonetheless. The key here is that the engraving setting takes away just enough material to create a raised pin on the part, without cutting all the way through the MDF or burning the surface.

Despite some damage when removing the work piece from the laser cutter, the part mates up well with the official LEGO brand parts. We’d be interested to see how the MDF cut parts hold up over time compared to real LEGO bricks made in ABS, which seem to last forever.

This isn’t the first make-your-own-LEGO hack we’ve seen – maybe you’d like to 3D print your own bricks on a printer made of LEGO?

Crypto Features: They’re Not For Girls

If you have worked in an office that contained a typewriter, the chances are you’ve been in the workplace for several decades. Such has been the inexorable advance of workplace computing. It’s a surprise then to discover that one of the desirable toys from many decades ago, the Barbie Typewriter, is still available. Are hipster parents buying toy versions of vintage office machinery for their children to use in an ironic fashion?

Gone though are the plastic versions of mechanical typewriters that would have been the property of a 1970s child. The modern Barbie typist has an electronic typewriter at her fingertips, with a daisy-wheel printer. We’re treated to a teardown of the recent models courtesy of Crypto Museum, who reveal a hidden feature, Barbie’s typewriter can encrypt and decrypt messages.

Now the fact that a child’s toy boasts a set of simple substitution cyphers is hardly the kind of thing that will set the pulses of Hackaday readers racing, after all simple letter frequency analysis is hardly new. But of course, the Crypto Museum angle is only part of this story.

This toy is made in a suitably eye-watering shade of pink, and sold by Mattel with Barbie branding. But it didn’t start life as a Barbie product, instead it’s licensed from the Slovenian manufacturer Mehano. The original toy makes no secret of the crypto functions, but though they persist in the software on the Barbie version they are mysteriously absent from the documentation. The achievements of American women are such that they have given us high-level languages and compilers, or their software has placed men on the Moon, yet it seems when they are young a brush with elementary cryptology is beyond them in the way that it isn’t for their Slovenian sisters. This is no way to nurture a future Grace Hopper or Margaret Hamilton, though sadly if your daughter is a Lisa Simpson this is just one of many dumbed-down products she’ll be offered.

If you see a Barbie electronic typewriter in a yard sale or similar, and you can pick it up for a few dollars, buy it. It’s got a simple daisywheel printer mechanism that looks eminently hackable. Just don’t buy it for your daughter without also printing out the Crypto Museum page for her as the missing manual.

When the Martian lander running her code has touched down safely, you’ll be glad you did.

Via Adafruit.

Power Wheels Rescued, Restored and Enhanced

It seems power wheels are like LEGO — they’re handed down from generation to generation.  [Nicolas] received his brand-new Peg-Perego Montana power wheels in 1997 as a Christmas present. After sitting in a barn for a decade, and even being involved in a flood, it was time to give it to his godchildren, though not without some restoration and added features. His webpages have a very good write-up, just shy of including schematics, but you’ll find an abbreviated version below.

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Alexa Brings Back Singing Fish, This Time It’s A Good Thing

Remember Big Mouth Billy Bass? That’s the singing fish with which you could torture family members by having it endlessly perform a rendition of either “Take Me to the River” or “Don’t Worry Be Happy”.

Now [Brian Kane], a teacher at the Rhode Island School of Design, has connected Amazon’s Alexa to the fish. Speak the “wake word”, “Alexa”, and the fish’s head turns to face you. Then ask it any question you’d normally ask Alexa and Alexa’s voice answers while the fish opens and closes its mouth in time to the words. Want to know the weather? Ask the fish, which you can see [Brian] do in the video below.

[Brian] hasn’t given details on how he’s done it but he’s likely made use of the Alexa Skills Kit, an SDK from Amazon that let’s you use the Alexa voice recognition and speech service with your own hardware (wetware, aquaware?), just as Amazon does with their home assistant, Echo .

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