Author: Lewin Day

How To Evolve A Radio

November 12, 2018 by 30 Comments

Evolutionary algorithms are an interesting topic of study. Rather then relying on human ingenuity and investigation to create new designs, instead, an algorithm is given a target to achieve, and creates “offspring”, iterating in an evolutionary manner to create offspring that get closer to the target with each generation.

This method can be applied to the design of electronic circuits, and is sometimes referred to as “hardware evolution”. A team from Duke University attempted exactly this, aiming to produce an oscillator using evolutionary techniques.

The team used a platform called the “evolvable motherboard”, or EM. The EM is a platform controlled by an attached computer, consisting of reconfigurable solid state switches that allow attached circuit components to be interconnected in every combination possible. These components may be virtually any electronic component; in this experiment, 10 bipolar transistors were used.

The evolutionary algorithm was given a fitness function that rewarded output amplitude and frequency, aiming to create an oscillator operating at 25KHz. However, the team noticed some interesting emergent behavior. The algorithm tended to reward amplification behavior from the circuit, leading to many configurations that oscillated poorly, but amplified ambient noise. In the end, the algorithm developed circuit configurations that acted as a radio, picking up and amplifying signals from the surrounding environment, rather than oscillating on their own. The evolutionary algorithm took advantage of the interaction between not only the circuit elements, but effects such as the parasitic capacitance introduced by the switching matrix and appeared to use the PCB circuit traces as an antenna.

The team conclude that evolutionary algorithms used in circuit design ignore human preconceptions about how circuits work, and will take advantage of sometimes unpredictable and unexpected effects to achieve their targets. This is a blessing and a curse, bringing unconventional designs to the fore, but also creating circuits that may not work well in a generalized environment. If your “oscillator” relies on a nearby noise source to operate, it may operate unpredictably in the field, for example.

We’ve seen evolutionary algorithms used before, such as being applied to robotic design.

The Naughty AIs That Gamed The System

November 11, 2018 by 22 Comments

Artificial intelligence (AI) is undergoing somewhat of a renaissance in the last few years. There’s been plenty of research into neural networks and other technologies, often based around teaching an AI system to achieve certain goals or targets. However, this method of training is fraught with danger, because just like in the movies – the computer doesn’t always play fair.

It’s often very much a case of the AI doing exactly what it’s told, rather than exactly what you intended. Like a devious child who will gladly go to bed in the literal sense, but will not actually sleep, this can cause unexpected, and often quite hilarious results. [Victoria] has created a master list of scholarly references regarding exactly this.

The list spans a wide range of cases. There’s the amusing evolutionary algorithm designed to create creatures capable of high-speed movement, which merely spawned very tall creatures that generated these speeds by falling over. More worryingly, there’s the AI trained to identify toxic and edible mushrooms, which simply picked up on the fact that it was presented with the two types in alternating order. This ended up being an unreliable model in the real world. Similarly, the model designed to assess malignancy of skin cancers determined that lesions photographed with rulers for scale were more likely to be cancerous.

[Victoria] refers to this as “specification gaming”. One can draw parallels to classic sci-fi stories around the “Laws of Robotics”, where robots take such laws to their literal extremes, often causing great harm in the process. It’s an interesting discussion of the difficulty in training artificially intelligent systems to achieve their set goals without undesirable side effects.

We’ve seen plenty of work in this area before – like this use of evolutionary algorithms in circuit design.

Making Colored Smoke Devices, The Right Way

November 10, 2018 by 15 Comments

Pyrotechnics are fun, and, with the proper precautions taken, safe enough to play with at home (usually). While it’s typical to purchase fireworks and smoke devices off the shelf, it’s actually possible to brew these up in a properly stocked home lab. [Tech Ingredients] is here to share the techniques behind producing your own super vibrant colored smoke devices at home.

Producing colored smoke requires a slightly different tack than making a simpler white smoke device. Colored smokes use dyes that are temperature sensitive, and thus the reaction temperature must be controlled carefully. This is achieved by choosing a potassium chlorate oxidiser, and combining it with magnesium carbonate and sodium bicarbonate, which help stop the reaction getting too hot. Sugar is used as the primary fuel, with both lactose and sucrose being fit for purpose. Color is then added with solvent-based dyes, readily sourced online. These are stable at higher temperatures than typical water-based food grade dyes, and thus are the best choice for creating thick, vibrant colored smoke.

[Tech Ingredients] does a great job of explaining both the theory behind the work, as well as the practical considerations necessary to be successful. The video is the result of much experimentation and work off-camera, which shows in the final presentation. If you’ve been working on your own pyrotechnic creations, be sure to hit up the tips line. Video after the break.

Continue reading “Making Colored Smoke Devices, The Right Way” →

Suspense Courtesy of Arduino, Mess of Wires

November 6, 2018 by 8 Comments

The ticking clock on the bomb is a Hollywood trope that simply refuses to die. Adding to the stress levels of the bomb squad and creating great suspense for the watcher, it’s always interesting to wonder why the average bomb maker is so courteous as to supply this information to law enforcement. Regardless, if you’d like to build a dramatic prop and are mature enough to do so responsibly, [Giorgio] has the guide you need.

The build is a straightforward one, relying on an Arduino to run the show. This is hooked up to a classic 7-segment LED display, upon which the countdown is displayed. For extra flair, an MP3 player is fitted to play the Mission Impossible theme. It all adds to the tension as you wipe the sweat from your brow, trying to decide if you’re cutting the right wire.

It’s a build that would be an excellent prop for a film production or a fun game at a holiday party. However, it’s also a build that could easily be mistaken for the real thing by those less technically inclined. Even the most innocuous homebrew projects have caused problems for innocent hackers in the past. Fake bombs can be incredibly dangerous, just like the real thing, so it’s important to be careful.

We’ve seen other takes on this kind of build before, too. As always, build responsibly.

The Bolt-On Peristaltic Pump

October 27, 2018 by 8 Comments

With the proliferation of 3D printing in the new millennium, stepper motors are no longer those idle junkbox inhabitants you pulled out of a dot matrix in 1994 and forgot about ever since. NEMA standard parts are readily available and knocking about just about everywhere. Now, you can readily turn a stepper motor into a peristaltic pump with just a few simple 3D printed parts.

The pump consists of a bracket that fits on to a standard NEMA-14 stepper motor frame. A rotor is then fitted to the motor shaft, constructed out of a 3D printed piece fitted with a series of standard roller bearings. These bearings roll against the tubing, pumping the working fluid.

The design uses the bearings to squeeze outwards against the tube’s own elastic resistance. Frictional wear is minimised by ensuring the tube is only pressed on by the bearings themselves, avoiding any contact between the tubing and hard plastic surfaces.

While the design is in its early stages of development, we’d be interested to see a pump performance comparison against other 3D printed peristaltic designs – we’ve seen a few before!

[Thanks to Baldpower for the tip!]

 

Ghost Rider Costume Is Smoking Hot

October 26, 2018 by 20 Comments

It’s that spooky time of year once again, with pumpkins and cobwebs as far as the eye can see. This year, [Mikeasaurus] has put together something really special – a Ghost Rider costume with some amazing effects.

The costume starts with the skull mask, which started with a model from Thingiverse. Conveniently, the model was already set up to be 3D printed in separate pieces. [Mike] further modified the design by cutting out the middle to make it wearable. The mask was printed in low resolution and then assembled. [Mike] didn’t worry too much about making things perfect early on, as the final finish involved plenty of sanding and putty to get the surface just right. To complete the spooky look, the skull got a lick of ivory paint and a distressed finish with some diluted black acrylic.

With the visual components complete, [Mike] turned his attention to the effects. Light is courtesy of a series of self-blinking LEDs, fitted inside the mask to give the eye sockets a menacing orange glow. However, the pièce de résistance is the smoke effect, courtesy of a powerful e-cigarette device and an aquarium pump. At 225W, and filled with vegetable glycerine, this combination produces thick clouds of smoke which emanate from the back of the wearer’s jacket and within the skull itself. Truly stunning.

[Mike] reports that the costume is scary enough that he has been banned from answering the door as Ghost Rider. We think it’s bound to be a hit, regardless. For another epic mask build, check out the Borderlands Psycho. Video after the break. Continue reading “Ghost Rider Costume Is Smoking Hot” →

Child’s Pushcar Gets Serious Horsepower

October 26, 2018 by 10 Comments

A pushcar is a great toy for a young child. They’re great excercise, and kids love anything on wheels. However, the bigger kids might want something with a little more grunt. [Master Milo] has just the thing – an engine from a concrete saw and the fabrication skills to match. (YouTube, embedded below.)

The build starts with the disassembly of the concrete saw, with covers, the saw drive and handle all removed. This leaves a 70 cc petrol engine with a centrifugal clutch already fitted. A steel frame is then built around the engine to mount the rest of the drivetrain. An intermediate shaft is used at the rear to allow for an extra level of gear reduction, and steering up front is handled with parts cribbed from an old ATV. The plastic shell of the pushcar is then fitted over the top and a seat constructed out of scrap wood.

Mechanical parts are in ready supply, with bearings and shafts all sourced from INDI, a European equivalent to McMaster Carr. By purchasing gears, belts and other parts off the shelf, it’s easy to make something that fits first time with a minimum of modification required.

The testing video is worth a watch – with both top speed and handling tests. The platform’s handling does leave something to be desired, but that’s half the fun in a build like this.

We’re no strangers to these projects around these parts – a modded Power Wheels is a great electric take on the same concept. Continue reading “Child’s Pushcar Gets Serious Horsepower” →