dice

40 Articles

Dice Roller Keeps Germs Out Of Your Snake Eyes

October 5, 2020 by 5 Comments

Do you need a to find a more sanitary way to roll the dice at your next socially-distanced board game gathering? [CJA3D]’s pop-o-matic mason jar dice roller can roll the bones two different ways — either by hitting that big, inviting arcade button, or though a web app that everyone can access on their own phones.

We think this looks great, and is a great reuse of a glass jar. The brains of this operation is an ESP8266, which drives a continuous-rotation servo underneath the dice. Push the button or use the web app and the servo disturbs the plate, moving the dice around.

Besides the sanitary aspect, one benefit of using the web app is that there are four different speed presets for the servo. As a bonus, [CJA3D] included the files for a pair of printed 6-sided dice. Click through to the project to see it in action.

We know you take games seriously, and so do we. Just look at this dice roller that uses machine vision to ensure fairness.

The Most Expensive D20 You’ll See Today

September 16, 2020 by 13 Comments

Roll your negotiation skill, because this d20 is a hefty one. The Tweet is also below. We are charmed by [Greg Davill]’s twenty-sided LED contraption, but what do we call it? Is it a device? A sculpture? A die? Even though “d20” is right on his custom controller PCB, we don’t think this will grace the table at the next elf campaign since it is rather like taking a Rolls Royce to the grocery store. Our builder estimates the price tag at $350 USD and that includes twenty custom PCB light panels with their components, a controller board, one battery pack, and the 3D printed chassis that has to friction-fit the light faces.

Power and communication for all the panels rely on twenty ribbon cables daisy-chained throughout the printed scaffolding, which you can see in the picture above. [Greg] made a six-sided LED cube last year, and there are more details for it, but we suspect he learned his lesson about soldering thousands of lights by hand. There are one-hundred-twenty LEDs per panel, times twenty, that is over two-thousand blinkenlights. We don’t yet have specs on the controller, but last time he used a SAMD51 processor to support over three-thousand lights. We don’t know where he’ll go next, but we’re game if he wants to make a chandelier for Hackaday’s secret underground lair.

(Editor’s Note: If you were at Supercon last year, and you got to play with this thing in the flesh, it’s worth it!)

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’75 Nixie Multimeter As Digital Dice

January 20, 2020 by 10 Comments

For the casual Monopoly or Risk player, using plain six-sided dice is probably fine. For other games you may need dice with much more than six sides, and if you really want to go overboard you can do what [John] did and build electronic dice with a random number generator if you really need to remove the pesky practice of rolling physical dice during your games of chance.

The “digital dice” he built are based on a multimeter from 1975 which has some hardware in it that was worth preserving, including a high quality set of nixie tubes. Nixies can be a little hard to come by these days, but are interesting pieces of hardware in their own right. [John] added some modern hardware to it as well, including an AVR microcontroller that handles the (pseudo) random number generation. A hardware switch tells the microcontroller how many sides the “die” to be emulated will need, and then a button generates the result of the roll.

This is a pretty great use for an old piece of hardware which would otherwise be obsolete by now. [John] considers this a “Resto-Mod” and the finish and quality of the build almost makes it look all original. It’s certainly a conversation piece at the D&D sessions he frequents.

These Dice Know If You’re Cheating

October 9, 2019 by 13 Comments

Fans of D&D are surely aware of the significance of a good pair of dice. What if your dice were not only stylish, but smart? For anyone who’s ever had to deal with playing board games with less than reputable siblings or friends, the electric die just might be your savior.

The dice are configured via Bluetooth, tracking rolls and stats over the course of gameplay captured by an accelerometer.

The PCB had to have a flexible surface – specifically in the shape of an unfolded icosahedron – in order to form the shape of the die which constrains the design to two layers. Each face contains an LED facing outwards to light up the number on that side. The LEDs are directly powered by a rechargeable battery, which uses a small coil for wireless inductive charging. Rather than opting for a Qi charger chipset, which regulates the maximum amount of power transmitted if the efficiency falls below a threshold, [Jean Simonet] uses a simpler charger setup using a full bridge rectifier, capacitors, and a linear regulator to create a stable 5V supply for the receiving end.

While the initial design for the die required an injection molded plastic shell, an easier solution was to simply cast the designs in resin. The electronics are placed into a dice mold and cast just as a regular die would be.

This luckily also solved the issue of needing to fit the components inside a screw-on container with a removable lid, which presented a hassle in terms of finding a battery that would fit the dimensions. The LEDs – purchased for cheap on Alibaba – are daisy chained to reduce the complexity of the routing.

One issue with the LEDs, however, is that the internal PWMs modulating the intensity remain on even at an intensity of 0, constantly drawing 21 mA (for the 21 LEDs on the die). This causes the battery to die after 2-3 hours. The solution [Simonet] used was to add a transistor to cut off power to the LEDs and to have the MCU toggle the transistor when the LEDs are turned off. Even this solution didn’t solve the entire problem since the LEDs still drain current from the data and clock lines, so those lines had to be low before going to sleep.

There were some stability issues with using a small buck converter to bring the LiPo voltage down to 3.3V, so the power regulation was done directly by the MCU instead. Switching the die off is controlled by a magnetic switch connected to a power buck converter that turns off logic when a magnet is present. This initially caused the LED control lines to become floating when power was turned off, turning the LEDs to arbitrary colors. The solution was to wire the output of the magnetic sensor to the MCU and to allow the software to handle the LEDs as well.

Maybe it’s because creator [Simonet] happens to be a game developer as well, but the early development stages of the electronic die (CAD, circuit schematics, prototyping, hand soldering components) were streamed on Twitch, adding some interactivity to even the build phase. The end result may be small, but these dice certainly have large brains!

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

August 4, 2019 by 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.

Automated Dice Tester Uses Machine Vision To Ensure A Fair Game

June 20, 2019 by 7 Comments

People take their tabletop games very, very seriously. [Andrew Lauritzen], though, has gone far above and beyond in pursuit of a fair game. The game in question is Star War: X-Wing, a strategy wargame where miniature pieces are moved according to rolls of the dice. [Andrew] suspected that commercially available dice were skewing the game, and the automated machine-vision dice tester shown in the video after the break was the result.

The rig is a very clever design that maximizes the data set with as little motion as possible. The test chamber is a box with clear ends that can be flipped end-for-end by a motor; walls separate the chamber into four channels to test multiple dice on each throw, and baffles within the channels assure randomization. A webcam is positioned below the chamber to take a snapshot of each “throw”, which is then analyzed in OpenCV. This scheme has the unfortunate effect of looking at the dice from the table’s perspective, but [Andrew] dealt with that in true hacker fashion: he ignored it since it didn’t impact the statistics he was interested in.

And speaking of statistics, he generated a LOT of them. The 62-page report of results from his study is an impressive piece of work, which basically concludes that the dice aren’t fair due to manufacturing variability, and that players could use this fact to cheat. He recommends pooled sets of dice to eliminate advantages during competitive play. 

This isn’t the first automated dice roller we’ve seen around these parts. There was the tweeting dice-bot, the Dice-O-Matic, and all manner of electronic dice throwers. This one goes the extra mile to keep things fair, and we appreciate that.

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Hash And Roll Your Way To Secure Passwords

March 30, 2019 by 17 Comments

In the electronic battlefield that is 2019, the realm of password security is fraught with dangers. Websites from companies big and small leak like sieves, storing user data in completely unsecure ways. Just about the worst thing you can do is use the same password across several services, meaning that an attack on one gives entry to multiple accounts. The challenge is to generate a unique and secure password for each and every application, and [Ilia]’s way of doing that is called HashDice.

No, it’s not a password manager, or an app – it’s a simple method that can be readily applied by anyone with the right tools. A simple dice is used to create random numbers, which are used to select words from a list to form the basic secret phrase. This is then combined with the name of the service or application to be accessed, the date, and a salt, before hashing using the SHA256 algorithm. The final hash is then truncated to create the password. You can do it all on a device that’s airgapped from the world, ensuring your core secret is never exposed, thus maintaining security.

There are some pitfalls to this method, of course. Many websites make things harder by requiring special characters or enforcing length limits on passwords. [Ilia] helpfully suggests several workarounds for this, but admits that no system is perfect in the face of these obstacles.

If you’re now wondering if your current password is safe, there are ways to investigate that, too.