String Racing Robots are Here !

This could be the start of a new thing. [HarpDude] showed off his String Car Racers over on the Adafruit forum. It’s like a small model cable car on caffeine. String up enough of them and go head to head racing with others.

A motor with a small pulley runs over a length of string stretched between 2 posts. Below the pulley, acting as a counterweight balance, is the rest of the racer. A Trinket board, motor driver, 9V battery and a pair of long lever micro switches to detect end of travel. The switches also help reverse the motor. A piece of galvanized wire acts as a guide preventing the String Car from jumping off the string. And discovering the benefits of a micro-controller design, as against discrete TTL/CMOS, old timer [HarpDude] added two operational modes via software. “Pong”, where the String Car keeps going back and forth over the string until it stops of (battery) exhaustion. The other mode is “Boomerang” – a single return trip back and forth.

We are guessing the next upgrade would be to add some kind of radio on the car (ESP8266 perhaps) and build an app to control the String Car. That’s when gaming could become fun as it opens up possibilities. One way to improve performance would be to add two “idler” pulleys in line with the main drive pulley, and then snake the string through the three of them. Now you know what to do with all of those old motors you’ve scavenged from tape drives, CD drives and printers. Let the Games begin!

Thanks [Mike Stone] for tipping us off on this.

Netflix and Chill – and Socks?

Waking up to spoilers in the last episode after falling asleep during the first episode of a Netflix binge-watching session ranks right up there on the list of first-world problems. Luckily there’s a solution in the form of a pair of Netflix enabled socks, which looks like a pretty neat wearable IoT project.

To be sure, calling these socks Netflix enabled is a bit of a stretch. Aside from the sock designs, which are based on popular Netflix original series, there’s nothing about the electronics that’s specific to the popular streaming service. These socks, with their Arduino Pro Trinket and accelerometer, detect when you stop moving and send an IR signal to do your bidding – pause the movie, kill the TV, or whatever. The electronic side of the build is pretty approachable – it’s just a couple of modules soldered together. The fiber arts side of the project might be a little outside the wheelhouse of the typical hardware hacker, but you can either team up with someone who knits – an experienced knitter, as socks are not a beginner’s pattern – or just slip the felt-clad hardware into your favorite comfy socks. We’d be a bit concerned about ESD protection for the hardware in the wooly environment, though.

“Netflix and chill” is the current version of last century’s “Watching the submarine races,” and as such the need for special socks or a custom Netflix switch for the occasion is a bit puzzling. Still, the underlying wearables idea is pretty good, with plenty of possibilities for expansion and repurposing.

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A Pocket-Sized Warp Core

Designed in the 2350s at the Utopia Planita shipyards, the warp core found in Galaxy class starships Yamoto, Odyssey, Challenger, and yes, Enterprise was a incomparable work of engineering, leading to more than one Daystrom Prize for its development. We’re still at least fifteen years away from the great [Zefram Cochrane]’s birth – and another 200 years until [Richard Daystrom] is born – but now, thanks to our advanced technology, a miniature warp core is within reach.

About a year ago, [Alex] found a warp core table lamp based on the one found on the Enterprise. it called out to him, but it’s a an extremely large build and only having a Solidoodle 2 as a 3D printer, [Alex] decided to scale it down to 25%.

Inside the warp core are a few Neopixel strips driven by a 5V Trinket. It’s not the ideal solution – if all the LEDs are turned on at the same time, the Trinket will brown out. It’s enough for an accurate pulsating effect, though, and was a nice enough gift to appease even the most discerning Trek fans he gave these mini models to.

Video below.

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Give your Multimeter a Wireless Remote Display

Multimeters are one of the key tools in a hardware hacker’s bench. For 90% of us, the meter leads are perfect for making measurements and looking over at the results. Sometimes you need a bit more distance though, and for that, [Ken Kaarvik] has created the Multimeter remote display. Remote displays are pretty handy when you want to measure something several feet away from your bench. They’re also great if you need to check something in an enclosed space, like a server rack or a refrigerator. Fluke actually sells multimeters with wireless displays, such as their model 233.

The key to this project is the FS9721 LP3 chip by Fortune Semiconductor. (PDF link) The FS9721 is essentially a system on chip (SOC) for multimeters. It contains a digital to analog to digital converter, an LCD driver, and a microcontroller. It also can send data out over a 2400 baud serial link. Two of [Ken’s] multimeters, the Digitek DT-4000ZC and a Fluke 17B, both have this chip. The Digitek has a 1/8″ plug for connecting to the outside world, while the Fluke requires some simple hardware mods to enable data output.

Since this was his entry for the Trinket EDC contest,  [Ken] connected the serial output of the FS9721 to an Adafruit Pro Trinket. The Trinket formats the data and sends it to an  nRF24L01+ 2.4GHz radio module. The receiving end has an identical radio, and another Pro Trinket. [Ken] actually built two wireless displays. One is a dual-boot Game Boy advance which has a really slick background on the color display. The other receiver utilizes a 128×64 OLED. The trinket, nRF24L01+ and display all fit neatly inside an Altoids tin.

Click past the break to see both wireless remote displays in action!

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Motion Activated Alarm for your Bag

Many of us carry around a bag with our expensive personal belongings. It can be a pain to carry a bag around with you all day though. If you want to set it down for a while, you often have to try to keep an eye on it to ensure that no one steals it. [Micamelnyk] decided to build a solution to this problem in the form of a motion sensing alarm.

The device is built around a Trinket Pro. The Trinket Pro is a sort of break out board for the ATMega328. It’s compatible with the Arduino IDE and also contains a USB port for easy programming. The Trinket is hooked up to a GY-521 accelerometer, which allows it to detect motion. When the Trinket senses that the device has been moved, it emits a loud high-pitched whine from a piezo speaker.

To arm the device, the user first holds the power button for 3 seconds. Then the user has ten seconds to enter their secret code. This ensures that the device is never armed accidentally and that the user always remembers the code before arming the device. The code is entered via four push buttons mounted to a PCB. The code and code length can both be easily modified in the Trinket software.

Once the code is entered, the status LED will turn solid. This indicates to the user that the device must be placed stationary. The LED will turn off after 20 seconds, indicating that the alarm is now armed. If the bag is moved for more than five seconds at a time, the alarm will sound. The slight delay gives the user just enough time to disarm the alarm. This parameter can also be easily configured via software.

Hacklet 29 – Altoids Mint Tin Projects

Altoids – they’ve been around since King George III was on the throne. These curiously strong mints have had a storied history, a copy of which is included in every tin. They taste pretty good, but most hackers and makers are more interested in the pocket-sized tin than the mints themselves. It may have been the ham radio operators who first used Altoids tins to hold their sensitive transmitter and receiver circuits. The metal case makes a perfect electromagnetic field shield. It wasn’t long before the tins found their way into thousands of projects. This week’s Hacklet features some of the best projects with Altoids (and other mint) tins on!

meeting-timerWe start with [Chad Lawson] and the Networking Group Timing Light. [Chad] has a networking meeting where each member has two minutes to introduce themselves. As is the case with most meetings, people tend to be a bit long-winded, running well beyond their allotted two minutes. The timing light contains an RGB LED which changes from green to yellow to red as a speaker’s time ticks away. The timer is reset by simply tilting the mint tin. [Chad] is hoping that the timer will serve as a gentle reminder to keep everyone on track time-wise.


radio2Next up is [Rjpope42] and his AM/FM Transmitter Pair. [Rjpope42] loves vintage tube radios, and wants to send his own signals to his amber glowing projects. Wiring an external audio input to a tube radio is pretty easy, but nothing beats a simple AM transmitter for convenience. Small FM transmitters are commonly available to add an MP3 player input to cars without an AUX audio in, but their AM counterparts have become rare. [Rjpope42] has built AM and FM transmitters, each of which will fit in a Mint Tin case. The AM transmitter can run on 9V or 12V, and even includes a USB power output for charging an MP3 player or phone!

da31k[John Hamann] entered Distance Analyzer 3000 in the Trinket EDC contest. While he didn’t win, it was still a great project, especially since this is [John’s] first serious Arduino project. The idea is to use a rotary encoder with a wheel to measure distances. Think of it like a mini version of a surveyor’s walking wheel. The Pro Trinket counts the pulses from the rotary encoder, then converts this to a distance in feet. We’d love to see [John] continue on the project. An ultrasonic distance sensor would be a great addition for multi-sensor distance reads!


ttotpFinally, we have [colonwq] with TTTOTP, a pro trinket Time based One Time Password (TOTP) generator. [colonwq] used the trinket to implement the well-known time based one time password algorithm. To implement a project like this, you need a stable time source. The ATmega328 isn’t very good at this, so [colonwq] used a Dallas DS1307 clock chip to keep track of things. The actual code is displayed on a 4 digit 7 segment display. When the button is pressed, the first half of the code is displayed. Once the button is released, the second half of the code is displayed for several seconds.


Need more mint? Check out our curiously awesome mint tin project list! Update and MeArm Giveaway has a few new features, including @username and #projectID. If you mention someone’s username with an @ in front of it, that user will get a notification in their stack. The same goes with mentioning a project ID with a # up front. To celebrate this, we’re giving away a pair of  special edition MeArms. All you have to do is leave a comment using the features on this project log. Huge thanks to [Jasmine] for setting all this up, and to [Ben] for letting us hijack his project for the week!

That’s it for this Hacklet, As always, see you next week. Same hack time, same hack channel, bringing you the best of!

Trinket EDC Contest Winners

It’s time to announce the winners of the Trinket Everyday Carry Contest! We’ve had a great 5 weeks watching the projects come together. A team of Hackaday staffers spent their weekend watching videos and selecting their top entries based on the contest rules. We had a really hard time picking the top three – the competition was tight, and there were quite a few awesome projects.

Without further ado, here are the winners!

1337toolFirst Prize: 1337 3310 tool. [Mastro Gippo] really knocked this one out of the park. He built a swiss army knife of a tool out of the iconic Nokia 3310 candybar phone. 1337 3310 tool is a graphing voltage and current meter, an ohmmeter, a continuity tester that plays the original Nokia ringtone, and a gaming machine which can play Tetris.  [Mastro Gippo] is 99% there with TV-B-Gone functionality as well. Amazingly, [Mastro Gippo] kept the Nokia look and feel in his user interface. He spent quite a bit of time grabbing data and bitmaps from the 3310’s original ROM.  [Mastro Gippo] is getting a Rigol DS1054Z scope to help iron out the bugs in his future projects!

pavaproSecond Prize: Pavapro – portable AVR programmer. [Jaromir] built an incredible pocket-sized microcontroller programming tool. Pavapro can read and edit text files, handle serial I/O at 9600 baud, and burn AVR microcontrollers. If that’s not enough, it can actually assemble AVR binaries from source. That’s right, [Jaromir] managed to fit an entire assembler on the Pro Trinket’s ATmega328 processor. Pavapro’s 16 button keypad won’t allow for much in the way of touch typing, but it does get the job done with T9 style text entry. The device is also extensible, we’re hoping [Jaromir] adds a few other architectures! PIC and MSP430 modes would be awesome!  [Jaromir] will be receiving a Fluke 179 multimeter with a 6 piece industrial electronics tip kit! We’re sure he’ll put it to good use.

robohandThird Prize: Robotic 3rd Hand. Let’s face it. We can’t all be Tony Stark. But [Tim] gets us a little bit closer with his awesome wearable entry. Need a tool? Just press the button, and Robotic 3rd Hand will give you a … hand. [Tim’s] creation utilizes the Pro Trinket to drive a servo which moves an incredibly well designed and 3D printed mechanism that lifts a screwdriver off the wearer’s wrist and places it into their hand. [Tim] originally was going to go with Electromyography (EMG) sensors to drive the hand, however he switched to a simple button when they proved problematic. We absolutely think this was the right decision for the contest – it’s always better to have a simpler but working project rather than a complex yet unreliable one. That said, we’d love to see him circle back and give EMG another try! [Tim’s] next project will be soldered up with the help of a Hakko FX888D with a tip kit. If things get a bit wobbly, he can use his new Panavise 324 Electronic Work center to keep everything steady.

If you didn’t make the top three in this contest, don’t give up! We’re going to be having quite a few contests this year. The top 50 entrants will receive custom Hackaday EDC Contest T-shirts. Check out the full list of 50 on!