Rocking Playmobil Wedding

Many of us have put our making/hacking/building skills to use as a favor for our friends and family. [Boris Werner] is no different, he set about creating a music festival stage with Playmobil figures and parts for a couple of friends who were getting married. The miniature performers are 1/24 scale models of the forming family. The bride and groom are on guitar and vocals while junior drums.

Turning children’s toys into a wedding-worthy gift isn’t easy but the level of detail [Boris Werner] used is something we can all learn from. The video after the break does a great job of showing just how many cool synchronized lighting features can be crammed into a tiny stage in the flavor of a real show and often using genuine Playmobil parts. Automation was a mix of MOSFET controlled LEDs for the stage lighting, addressable light rings behind the curtain, a disco ball with a stepper motor and music, all controlled by an Arduino.

Unless you are some kind of Playmobil purist, this is way cooler than anything straight out of the box. This is the first mention of Playmobil on Hackaday but miniatures are hardly a new subject like this similarly scaled space sedan.

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AI Watches You Sleep; Knows When You Dream

If you’ve never been a patient at a sleep laboratory, monitoring a person as they sleep is an involved process of wires, sensors, and discomfort. Seeking a better method, MIT researchers — led by [Dina Katabi] and in collaboration with Massachusetts General Hospital — have developed a device that can non-invasively identify the stages of sleep in a patient.

Approximately the size of a laptop and mounted on a wall near the patient, the device measures the minuscule changes in reflected low-power RF signals. The wireless signals are analyzed by a deep neural-network AI and predicts the various sleep stages — light, deep, and REM sleep — of the patient, negating the task of manually combing through the data. Despite the sensitivity of the device, it is able to filter out irrelevant motions and interference, focusing on the breathing and pulse of the patient.

What’s novel here isn’t so much the hardware as it is the processing methodology. The researchers use both convolutional and recurrent neural networks along with what they call an adversarial training regime:

Our training regime involves 3 players: the feature encoder (CNN-RNN), the sleep stage predictor, and the source discriminator. The encoder plays a cooperative game with the predictor to predict sleep stages, and a minimax game against the source discriminator. Our source discriminator deviates from the standard domain-adversarial discriminator in that it takes as input also the predicted distribution of sleep stages in addition to the encoded features. This dependence facilitates accounting for inherent correlations between stages and individuals, which cannot be removed without degrading the performance of the predictive task.

Anyone out there want to give this one a try at home? We’d love to see a HackRF and GNU Radio used to record RF data. The researchers compare the RF to WiFi so repurposing a 2.4 GHz radio to send out repeating uniformed transmissions is a good place to start. Dump it into TensorFlow and report back.

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3D Printed Jet Engine

In specific applications, jet engines are often the most efficient internal combustion engines available. Not just for airplanes, but for anything that needs to run on a wide variety of fuels, operate at a consistent high RPM, or run for an extended amount of time. Of course, most people don’t have an extra $4,000 lying around to buy a small hobby engine, but now there’s a 3D-printed axial compressor available from [noob_sauce].

As an aero propulsion engineer, [noob_sauce] is anything but a novice in the world of jet engines. This design is on its fourth iteration with a working model set to be tested by the end of the month. Additionally, [noob_sauce] created his own software that was necessary for the design of such a small, efficient jet engine which has all been made available on Git. So far the only part that has been completed has been the compressor stage of the engine, but it’s still a very impressive build that we don’t see too often due to the complexity and cost of axial compressor jet engines.

Of course, there are some less-complex jet engines that are available to anyone with access to a hardware store and a welder which don’t require hardly any precision at all. While they’re fun and noisy and relatively easy to build, though, they don’t have near the efficiency of a jet engine like this one. The build is impressive on its own, and also great that [noob_sauce] plans to release all the plans so that anyone can build one of these as well.

Incredibly Simple Stage For Product Photos

If you’ve ever tried to take nice photos of small objects in your home, you might have found that it can be more difficult than it seems. One way to really boost the quality of your photos is to get proper lighting with a good background. The problem is setting up a stage for photos can be expensive and time-consuming. [Spafouxx] shows that you don’t need to sink a lot of money or energy into a setup to get some high quality photos.

His lighting setup is very simple. Two wooden frames are built from scraps of wood. The frames stand upright and have two LED strips mounted horizontally. The LEDs face inwards toward the object of the photos. The light is diffused using ordinary parchment paper that you might use when baking.

The frames are angled to face the backdrop. In this case, the backdrop is made of a piece of A4 printer paper propped up against a plastic drink bottle. The paper is curved in such a way to prevent shadows. For being so simple, the example photo shows how clean the images look in the end.

Robot theater isn’t so much for the actors as the stagehands

robot-theater

[Chris Rybitski] developed this low-profile robot to help move scenery on stage. The test footage shows it to be spry and able to move hundreds of pounds of cargo. The demo shows the addition of a wooden platform about twice the length of the metal chassis with casters at each end to support the extra weight. It seems to have no problem moving around with the weight of a couple of human passengers on board.

Crafty systems for changing huge sets has long made the theater a natural breeding ground for hacks. Balanced turn tables, rails systems, and the like are common place. But we think this has a ton of potential. Right now the electronics seem convoluted, as there is an Arduino running the motors which connects to the LAN using an Ethernet shield and that Linksys wireless router.

We think he should patch directly into the serial port of the router. If he loads DD-WRT or OpenWRT he can easily make the remote control a web interface. We also wonder about the possibility of making it a line-follower that can precisely position itself automatically using patterns on the floor.

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Maggy, locked and loaded

maggy

Some readers may remember [Paul] from his project Jak, the blackjack robot; but his interests have moved toward coil gun creation. Maggy, his latest weapon, may not be the prettiest of coil gun we’ve seen, or the most environmentally friendly, but does look to be promising. Featuring a triple stage, logic based accelerator instead of the typical single stage, it can fire a 10 gram projectile (theoretically) up to 85 km/h! Check out how he’s gone from a single pistol to his current monster on his site, and a video of his work in progress after the jump. Continue reading “Maggy, locked and loaded”