Little Flash Charges In 40 Seconds Thanks To Super Capacitors

November 21, 2019 by Gerrit Coetzee 10 Comments

We’ve all committed the sin of making a little arduino robot and running it off AA batteries. Little Flash is better than that and runs off three 350 F capacitors.

In fact, that’s the entire mission of the robot. [Mike Rigsby] wants people to know there’s a better way. What’s really cool is that 10 A for 40 seconds lets the robot run for over 25 minutes!

The robot itself is really simple. The case is 3D printed with an eye towards simplicity. The brains are an Arduino nano and the primary input is a bump sensor. The robot runs around randomly, but avoids getting stuck with the classic reverse-and-turn on collision.

It’s cool to see how far these capacitors have come. We remember people wondering about these high priced specialty parts when they first dropped on the hobby scene, but they’re becoming more and more prevalent compared to other solutions such as coin-cells and solder tab lithium batteries for PCB power solutions.

Retrotechtacular: 934 MHz CB Radio

November 21, 2019 by Jenny List 49 Comments

The radio spectrum is carefully regulated and divided up by Governments worldwide. Some of it is shared across jurisdictions under the terms of international treaties, while other allocations exist only in individual countries. Often these can contain some surprising oddities, and one of these is our subject today. Did you know that the UK’s first legal CB radio channels included a set in the UHF range, at 934 MHz? Don’t worry, neither did most Brits. Behind it lies a tale of bureaucracy, and of a bungled attempt to create an industry around a barely usable product.

Hey, 2019, Got Your Ears On?

Did this car make you want a CB radio? Stuurm [CC BY-SA 3.0]

Mention CB radio in 2019 it’s likely that the image conjured in the mind of the listener will be one from a previous decade. Burt Reynolds and Jerry Reed in Smokey and the Bandit perhaps, or C. W. McCall’s Convoy. It may not be very cool in the age of WhatsApp, but in the 1970s a CB rig was the last word in fashionable auto accessories and a serious object of desire into which otherwise sane adults yearned to speak the slang of the long-haul trucker.

If you weren’t American though, CB could be a risky business. Much of the rest of the world didn’t have a legal CB allocation, and correspondingly didn’t have access to legal CB rigs. The bombardment of CB references in exported American culture created a huge demand for CB though, and for British would-be CBers that was satisfied by illegally imported American equipment. A vibrant community erupted around UK illegal 27 MHz AM CB in the late 1970s, and Government anger was met with campaigning for a legal allocation. Brits eventually got a legal 27 MHz allocation in November 1981, but the years leading up to that produced a few surprises.

Continue reading “Retrotechtacular: 934 MHz CB Radio” →

Gaze Deeply Into These Infinity Mirror Coasters

November 21, 2019 by Tom Nardi 11 Comments

Infinity mirrors have been gaining in popularity recently, thanks in no small part to the availability of low-cost RGB LED strips to line them with. Generally such pieces are limited to wall art, or the occasional table build, which is what makes these infinity mirror drink coasters from [MnMakerMan] so unique.

Built from an ATtiny85 and a WS2812B LED strip nestled into a 3D printed enclosure, these coasters are relatively cheap and easy to assemble should you want to run a few off before the holiday party season. [MnMakerMan] mentions the LEDs can consume a decent amount of energy, so he’s included a module to allow recharging of the internal 3.7 V 1500 mAh battery over USB.

Of course, a couple of PLA pieces and a custom PCB doesn’t make an infinity mirror. To achieve the desired effect, he’s created a stack consisting of a 4″ glass mirror, a 1/8″ thick plexiglass disc, and one-way mirror tint film. The WS2812B strip mounted along the circumference lights up the void between the two surfaces, and produces a respectable sense of depth that can be seen in the video after the break.

This isn’t the first high-tech piece of surface protection we’ve seen around these parts, as some very nice wirelessly charged supercapacitor coasters were entered into the 2019 Hackaday Prize. Of course, if you’re of the opinion that coasters should remain as cheap as possible, we’ve seen a number of automated attempts to add some flair to the classic paperboard discs.

Continue reading “Gaze Deeply Into These Infinity Mirror Coasters” →

Training Bats In The Random Forest With The Confusion Matrix

November 21, 2019 by Pat Whetman 4 Comments

When exploring the realm of Machine Learning, it’s always nice to have some real and interesting data to work with. That’s where the bats come in – they’re fascinating animals that emit very particular ultrasonic calls that can be recorded and analysed with computer software to get a fairly good idea of what species they are. When analysed with an FFT spectogram, we can see the individual call shapes very clearly.

Nyctalus noctula (noctule bat)

Myotis nattereri (natterera’s bat)

Plecotus auritus (brown long eared)

Pipistrellus pipistrellus (common pipistrelle)

Creating an open source classifier for bats is also potentially useful for the world outside of Machine Learning as it could not only enable us to more easily monitor bats themselves, but also the knock on effects of modern farming methods on the natural environment. Bats feed on moths and other night flying insects which themselves have been decimated in numbers. Even in the depths of the countryside here in the UK these insects are a fraction of the population that they used to be 30 years ago, but nobody seems to have monitored this decline.

So getting back to our spectograms, it would be perfectly reasonable to throw these images at a convolutional neural network (CNN) and use an image feature-recognition strategy. But I wanted to explore the depths of the mysterious Random Forest. Continue reading “Training Bats In The Random Forest With The Confusion Matrix” →

Jackpot!: The Trials And Tribulations Of Turning A Slot Machine Into An ATM

November 21, 2019 by Danie Conradie 15 Comments

Have you ever wished that slot machines dispensed money as easily as an ATM? Well so did [Scotty Allen] from Strange Parts, so in collaboration with his friend [Matt] decided to combine the two. After a four-month journey fraught with magic smoke and frustration, they managed to build a fully functional ATM slot machine.

The basic idea is that you insert your card and enter your pin like on a normal ATM, select your winning amount, and pull the lever. This sets wheels spinning, which come to a stop with three-of-a-kind every time, and you win your own money as a bucket load of coins with all the accompanying fanfare. The project took way longer than [Scotty] expected, and he ended up missing his original deadline to show off the machine at DEF CON.

They started with an old broken Japanese slot machine, and replaced the control board with an Arduino Due after a lot of reverse engineering and hacking. [Scotty] did a cool video just on getting the original vacuum fluorescent display working. Integrating the ATM parts proved to be the biggest challenge, with number of very expensive parts releasing their magic smoke or getting bricked in the process. [Scotty] came up with an ingeniously simple hack to interface the ATM hardware with the Arduino. The cash note dispenser uses multiple sensors to detect if there are notes loaded and if one is successfully dispensed. These were spoofed by the Arduino, which controls two coin hoppers instead to dispense appropriate amount of quarters or pennies. The build was rounded off with some very neat custom graphics on the glass panels, and the machine was finally showed off at a local arcade.

This was an awesome project, and we can appreciate the fact that [Scotty] made no attempt to hide the real emotional roller coaster that anyone who has worked on a large project knows, but is rarely documented in logs. [Scotty] has made a name for himself by building his own iPhone from parts and touring Shenzhen’s many factories. Check out the videos after the break Continue reading “Jackpot!: The Trials And Tribulations Of Turning A Slot Machine Into An ATM” →

Print From The ESP8266, Courtesy Of Google

November 21, 2019 by Tom Nardi 23 Comments

The ESP8266 has become the hacker’s microcontroller of choice because it’s exceptionally easy to get the chip connected to the network and talking to other devices. The fact that it’s also absurdly cheap is just a bonus. Since nearly every piece of electronics you buy today is “smart” enough to include some form of Internet control, that means there’s no shortage of gadgets these MCUs can potentially poke and prod.

In their latest tip, [TecnoProfesor] shows how you can interface the ESP8266 with Google’s Cloud Print, a service that enables simple remote printing over the web without having to worry about having the proper device drivers. Remote printing from the ESP8266 might seem like little more than a gag at first glance, but if you’re the kind of person who likes to have hard copies of data, adding the capability to generate a daily printed report to your weather station could be a nice weekend project.

[TecnoProfesor] provides explanations and source code for printing documents of various sizes from both the ESP8266’s internal flash storage and an SPI-attached SD card. Towards the end of the write-up, there’s even some explanation of how the setPrintDocument() function of the Cloud Print API can be used in more advanced scenarios, such as printing web pages or documents stored in Google Drive.

When we see microcontrollers connected to printers, they’re usually of the small thermal kind. Being able to access “real” printers with such a simple technique offers some interesting possibilities, though like most technology, there’s potential for it to be misused.

[Thanks to Andrew for the tip.]

DIY Photo Backup In The Field

November 20, 2019 by Bryan Cockfield 29 Comments

They say a file isn’t backed up if it isn’t backed up twice. This is easy enough to do if you have access to your computer and a network, but if you’re a photographer you might end up in a place without either of these things and need a way to back up the files you just created. For that you’ll need a specialized photo backup tool which you can easily build yourself.

While commercial offerings are available which back up files locally from a camera’s SD card to another medium, they suffer from a high price. [André]’s solution can be had for a fraction of that cost. Using a Raspberry Pi Zero, a tiny USB hub, and a high capacity jump drive, a photographer can simply plug in an SD card and the Pi will handle the backups with varying levels of automation. The software that [André] made use of is called Little Backup Box written by [Dmitri Popov] and can be used typically as an automatic backup for any other device as well.

This is a great solution to backing up files on the go, whether they’re from a camera or any device that uses an SD card. Removable storage is tiny and easily lost, so it’s good to have a few backups in case the inevitable happens. Raspberry Pis are an ideal solution to data backup, and can even be battery powered if you’re really roughing it for a few days.