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 Hackaday.io!

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!

Hackaday.io Update and MeArm Giveaway

Hackaday.io 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 Hackaday.io!

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 Hackday.io!

Trinket EDC Contest: USB Calipers

[Lou]’s entry for the Trinket EDC Contest is a great addition to the ubiquitous digital calipers found on workbenches and eBay resellers the world over. It translates the value displayed on the calipers to a USB HID interface for logging all those tricky measurements at the push of a button.

Most of the digital calipers you’ll find at Harbor Freight or on eBay are pretty much the same. There are two pads on the caliper’s PCB that give any microcontroller the ability to read what is being measured. It’s done with a 24-bit encoding scheme, where each bit is a nearly-BCD measurement in units of 1/1000 of an inch or 1/100 of a millimeter. After decoding the value, [Lou]’s trinket sends a few numbers to a computer over a USB HID interface.

Simply sending a measurement to a computer over USB wasn’t enough for [Lou]. He added three buttons to the project for typing multiple characters. The first button just sends Enter to the computer, the second sends a comma, and the third sends “/2 (Enter)”, exactly what you need to input the radius of something when measuring the diameter.

This was a project for the Trinket EDC Contest that ended a few hours ago. Nobody knows who the winner is, but there are some pretty cool prizes up for grabs including the new Rigol scope, a Fluke 179, and a soldering station.

Trinket EDC Contest – The Deadline Approaches

We’ve got just under 2 days left in the Trinket Everyday Carry Contest. With 79 entries, and t-shirts going to the top 50 entrants, you’ve got pretty darn good odds of getting a shirt out of all of this! The design is great too, [Joe Kim] really did a great job with it!



The idea is simple: Build small, pocketable projects which are useful everyday.

We explained everything in our announcement post, and the full rules are available on the contest page. But just as a reminder, the main requirements are

  • The project Must use a Pro Trinket, or a board based on the open source Pro Trinket design.
  • The project must have at least 3 project logs
  • The project must have at least one video
  • The Hackaday.io project must include enough documentation to allow an average hobbyist to replicate the project

There are already some awesome entries vying for the top prize, but who knows – someone may come out of nowhere and walk away with a sweet Rigol ds1054z oscilloscope!


The contest deadline is January 3rd, at 12:00 am PDT. The clock is ticking, so stop waiting, and go build something awesome! Good luck to everyone who enters!

Trinket EDC Contest Entry: Shorty

Sometimes finding a short-circuit is easy, especially after the magic smoke has escaped. Finding a short on a newly etched or milled board though, can be a maddening task. Many of us have been there – wrestling with multimeter probes under a magnifier trying to find the offending bit of copper that is the source of all our problems. [Jaromir] designed Shorty to make this task a little bit easier.

Shorty is a short-circuit finder – but it’s not exactly like the one you would find on a typical multimeter.  [Jaromir] used MCP6041 Op-Amp to detect resistances down to the order of tens of milliohms. Determining an exact resistance measurement at these levels would require a heck of a lot of calibration. When looking for a short though, [Jaromir] is only concerned with the relative value – is he getting closer to or further away from the short. He determines this by sound. The Op-Amp output is sent to the Pro Trinket’s ADC input. The trinket drives a speaker with lower or higher tones based upon the ADC voltage. Much like the childhood game of “hot and cold”, Shorty will direct you right to your short!

There’s still time to enter the Trinket Everyday Carry Contest. The main contest runs until January 2, but we’re having random drawings every week! Don’t forget to write a project log before the next drawing at 9pm EST on Tuesday, December 30th. You and all of the other entrants have a chance to win a Teensy 3.1 from The Hackaday Store!

Trinket EDC Contest Entry: Can I Borrow a Feeling?

We got a case of the Mondays just reading about [Sascha]’s work environment. Get this: every morning, first thing, the whole team gets together to check in and share how they’re all feeling. And they can’t even be candid about it—there’s actually an approved list of feeling descriptors, both good and bad. It’s an admittedly big list that includes, interestingly enough, both ‘tortured’ and ’embarrassed’. Yeah. We think something like group t’ai chi on the roof each morning sounds a lot more relaxing. Since [Sascha] is between a rock and a hard place on this one, it was time to let chance take over. He raised his HaD-imprinted Trinket skyward and Can I Borrow a Feeling? was born.

The gist is simple: [Sascha] abstracts his disposition out to either ‘good’ or ‘bad’ and pushes the corresponding button. The Trinket accesses an array and returns a randomly selected feeling to the LCD. Since the official list of feelings is about 300 words long, [Sascha] has to push the data into PROGMEM. He used good old Excel to split the list in twain, and her formulas came in very handy for centering the result on the LCD. Once [Sascha] knew how it would all fit together, he designed a cool enclosure in CorelDRAW and turned on the laser cutter. See the Spreadsheet of Acceptable Words for yourself on GitHub, and pick up the code and enclosure file while you’re there.

There’s still time to enter the Trinket Everyday Carry Contest.  The main contest runs until January 2, but we’re having random drawings every week! Don’t forget to write a project log before the next drawing at 9pm EST on Tuesday, December 30th. You and all of the other entrants have a chance to win a Teensy 3.1 from The Hackaday Store!


[Vasilis] has entered Lazydoro in the Trinket Everyday Carry Contest.  Lazydoro is designed to get him up off his backside, and walking around. Recent medical research has determined that sitting too long is a bad thing. In fact,  Dr. David Agus has been quoted by Nike as saying that sitting for several hours is as bad as smoking (wayback machine link). While we’re not exactly up on the latest medical trends, we can definitely see that getting up and walking around a bit never hurt anyone. Lazydoro will alert [Vasilis] once every 20 minutes or so to get up and stretch his legs a bit.

[Vasilis] plans to pair a Pro Trinket with an accelerometer module, specifically an ADXL377 from Analog Devices. The accelerometer will allow Lazydoro to determine if [Vasilis] has moved around. If 20 or 30 minutes go by without major movement, Lazydoro will nudge him to get up and take a walk.

Since shipping to Greece takes awhile, [Vasilis] is developing with an Arduino Uno and a ADXL345 while he waits for his parts to arrive. He’s hacked this into a wrist mounted device for testing. One thing  [Vasilis]  hasn’t figured out yet is how to alert the user to move around. A small vibrating motor would probably work – but we’d suggest electric shocks. A good zap always puts the spring in our step!

There is still plenty of time to enter the Trinket Everyday Carry Contest.  The main contest runs until January 2, but we’re having random drawings every week! Don’t forget to write a project log before the next drawing at 9pm EDT on Tuesday, December 23. You and all of the other entrants have a chance to win a Cordwood Puzzle from The Hackaday Store!