Gesture Controlled Doom

July 22, 2019 by Zoe Skyforest No comments

DOOM will forever be remembered as one of the founding games of the entire FPS genre. It also stands as a game which has long been a fertile ground for hackers and modders. [Nick Bild] decided to bring gesture control to iD’s classic shooter, courtesy of machine learning.

The setup consists of a Jetson Nano fitted with a camera, which films the player and uses a convolutional neural network to recognise the player’s various gestures. Once recognised, an API request is sent to a laptop playing Doom which simulates the relevant keystrokes. The laptop is hooked up to a projector, creating a large screen which allows the wildly gesturing player to more easily follow the action.

The neural network was trained on 3300 images – 300 per gesture. [Nick] found that using a larger data set actually performed less well, as he became less diligent in reliably performing the gestures. This demonstrates that quality matters in training networks, as well as quantity.

Reports are that the network is fairly reliable, and it appears to work quite well. Unfortunately, playability is limited as it’s not possible to gesture for more than one key at once. Overall though, it serves as a tidy example of how to do gesture recognition with CNNs.

If you’re not convinced by this demonstration, you might be interested to learn that neural networks can also be used to name tomatoes. If you don’t want to roll your own pose detection, check out this selfie drone that uses CMU’s OpenPose library. Video after the break.

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A Baseball Cap That Films The Past

July 21, 2019 by Zoe Skyforest 17 Comments

The vast majority of cameras will start recording at the press of a button. This is perfectly acceptable behaviour if you wish to film something that hasn’t happened yet. If you want to film something that’s already over, you’re out of luck. [Johan Link] has built a camera designed to do just that, however, and put it on a cap.

The project consists of a Raspberry Pi 3B, combined with a 1080p USB webcam and a 5000 mAh power bank. These are attached to a baseball cap in order to shoot footage from the point of view of the wearer. The camera records continuously, saving the last 7 seconds of recorded video when the button is pressed — perfect for capturing things just after they’ve happened.

It’s a rolling record feature similar to that included with many dashcams and action cameras. Software is available on Github for those interested. While [Johan] has chosen a New York Yankees hat as the basis for the build, we’re confident it should work similarly well with your Seattle Seahawks cap. Raiders fans should contact the garment manufacturer.

Building A Bigger Cloud Chamber

July 20, 2019 by Zoe Skyforest 11 Comments

Cloud chambers are an exciting and highly visual science experiment. They’re fascinating to watch as you can see the passage of subatomic particles from radioactive decay with your very own eyes. Many elect to build small chambers based on thermoelectric Peltier elements, but [Cloudylabs] decided to do something on a grander scale.

It’s a hefty chamber, and a very clean build.

[Cloudylabs] started building cloud chambers after first seeing one in a museum back in 2010. The first prototype was an air-cooled Peltier device, with a cooled area of just 4x4cm. Over the years, and after building many more Peltier-based chambers, it became apparent that the thermoelectric modules were somewhat less than robust, often failing after many thermal cycles. Wanting to take things up a notch, [Cloudylabs] elected to build a much larger unit based on phase-change technology, akin to the way a refrigerator works.

The final product is astounding, consisting of a 32x18cm actively cooled area mounted within a large glass viewing case. A magnet is mounted underneath which causes certain particles to curve in relation to the field, as well as an electrically charged grid up top. The chamber is capable of operating for up to 12 hours without requiring any user intervention.

Cloud chambers are always beautiful, and even moreso at this larger scale. When radioactive materials are introduced into the chamber the trails generated are long and easily visible. It’s a daunting build however, and the final product weighs over 30 kilograms. You might want to start with something a little smaller for your first build. Video after the break.

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Breathing LED Done With Raw Logic Synthesized From A Verilog Design

July 20, 2019 by Zoe Skyforest 16 Comments

Breathing LEDs are an attractive adornment on many electronic devices. These days they’re typically controlled by software but of course there were fading effects back in the days of analog too. [Pepijn de Vos] mixes a little of the new and the old by building a hardware-based fader from a Verilog design and even too the time to explain the process in depth.

Rather than using a microcontroller and software, [Pepijn] wrote the logic required to make the LED “breathe” in the hardware description language, Verilog. You may be familiar with this for FPGAs, but using it to plan out a build with logic chips is just as apt a use. The Verilog was synthesized into a circuit using 74-series logic chips, with the help of work by [Dan Ravensloft] who has made a library for the Yosys Open Synthesis Suite. With the addition of a basic clock circuit, the LED is made to breathe and the rate can be controlled by changing the clock speed.

It’s a fun way to experiment with both Verilog and old-school logic, albeit one that may not scale well. An interesting side note from the Twitter thread, [Dan] estimates that with current settings the PicoRV32 CPU would require over 2000 chips to build. Regardless, it’s an interesting tool and one that likely has further scope for experimentation.

First patented by Apple way back in 2002, the breathing LED has been a popular project for those learning electronics. We’ve even seen it on motorbikes. Video after the break.

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Designing Compact Gasoline Generator Prototype For Drone Use

July 20, 2019 by Zoe Skyforest 39 Comments

Lithium batteries and brushless motors helped make multirotor drones possible, but batteries only last so long. Liquid fuels have far greater energy densities, but have not been widely applied in these roles. [Tech Ingredients] has been experimenting with a compact gasoline-fueled generator, with the aim to extend drone flight times well beyond what is currently possible with batteries (Youtube link, embedded below).

The build began with a single-cylinder, four stroke engine. However, torque spikes and vibration made things difficult. After some iteration, the design settled on employing two single-cylinder two stroke engines, fitted with a timing belt to keep them 180 degrees out of phase. In combination with a pair of balanced flywheels, this keeps vibration to a minimum. Brushless motors are used as generators, combined with rectifier diodes and capacitors to smooth the voltage output. The generator is intended to be used in parallel with a lithium battery pack in order to ensure the drone always has power available, even in the event of a temporary malfunction.

This is a build with plenty of promise, and we can’t wait to see what kind of flight time can be achieved once the system is finished and flight ready. We’ve seen others experimenting with hybrid drones, too.

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DIY Scintillation Detector Is Mighty Sensitive

July 19, 2019 by Zoe Skyforest 24 Comments

Geiger counters are a popular hacker project, and may yet prove useful if and when the nuclear apocalypse comes to pass. They’re not the only technology out there for detecting radiation however. Scintillation detectors are an alternative method of getting the job done, and [Alex Lungu] has built one of his own.

Scintillation detectors have several benefits over the more common Geiger-Muller counter. They work by employing crystals which emit light, or scintillate, in the presence of ionizing radiation. This light is then passed to a photomultiplier tube, which emits a cascade of electrons in response. This signal represents the level of radioactivity detected. They can be much more sensitive to small amounts of radiation, and are more sensitive to gamma radiation than Geiger-Muller tubes. However, they’re typically considered harder to use and more expensive to build.

[Alex]’s build uses a 2-inch sodium iodide scintillator, in combination with a cheap photomultiplier tube he scored at a flea market for a song. [Jim Williams]’s High Voltage, Low Noise power supply is used to run the tube, and it’s all wrapped up in a tidy 3D printed enclosure. Output is via BNC connectors on the rear of the device.

Testing shows that the design works, and is significantly more sensitive than [Alex]’s Geiger-Muller counter, as expected. If you’re interested in measuring small amounts of radiation accurately, this could be the build for you. We’ve seen this technology used to do gamma ray spectroscopy too.

Making Flexible Overmolded Parts With Urethane Resin

July 19, 2019 by Zoe Skyforest 11 Comments

Resin casting videos have taken social media by storm of late. Everything from inlaid driftwood tables to fancy pens are getting the treatment. Pouring some nicely colored epoxy is straightforward enough, but it’s just the tip of the iceberg. [Eric Strebel] has some serious skills in resin casting, and has lately been working on some overmolded electroniics with urethane resin (Youtube link, embedded below).

The build starts with the creation of a silicone mold, using a 3D printed SLA master. The part in question is for a prototype medical device, and requires overmolding, in which a flexible PCB is covered in flexible urethane. Wooden pins are used to allow the flexible PCB to clip into the mold for accurate location, and a small shield is placed over the metal contacts of the PCB to avoid them being covered in silicone.

Initial tests are done with an empty mold to determine the correct material to use, before the actual parts are ready to produce. [Eric] takes great care with the final production, as any mistakes would waste the expensive prototype PCBs provided to him by the client. With the electronics placed in the mold, the resin is degassed and carefully injected, using a syringe to minimise the chance of any air bubbles. With some delicate cleanup by hand, the completed parts are ready for delivery.

It’s a process that covers the basics of overmolding for a prototype part, as well as showing off [Eric]’s skill at producing quality prototype parts. We’ve seen [Eric]’s work before, too – like his discussion of the value of cardboard in product design. Video after the break.

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