Security camera detecting a human

Motion Detecting Camera Recognizes Humans Using The Cloud

[Mark West] and his wife had a problem, they’d been getting unwanted guests in their garden. Mark’s solution was to come up with a motion activated security camera system that emails him when a human moves in the garden. That’s right, only a human. And to make things more interesting from a technical standpoint, he does much of the processing in the cloud. He sends the cloud a photo with something moving in it, and he’s sent an email only if it has a human in it.

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Self-lacing LEGO shoe

Self-Lacing LEGO Power Shoe

Here’s a blast from the past, or future, reminiscent of the self-lacing shoes from Back to the Future Part II. [Vimal Patel] made his own self-lacing shoe using LEGO “bolted” to the shoe’s sole. We think these are cooler than the movie version since we get to see the mechanism in action, urging it on as the motor gets loaded down pulling the laces for that last little bit of tightness.

The electronics are all LEGO’s Power Functions parts. A Dremel was used to make holes in the soles to hot glue LEGO pieces for four attachment points. The attachment points are permanent but the rest can be easily removed. In case you want to look them up or make your own, he’s using the using the 8878 rechargeable LiPo battery box, the 88003 L-motor, the 8884 IR receiver, and the 8885 IR remote control. That’s right, these shoes are laced up under command of an IR remote control, well, provided the battery box is powered on. There’s a 1:24 worm gear reduction to get the needed torque.

This was a quick build for [Patel], done over two afternoons. He initially tried with the winding axle behind the heel but that didn’t work well so he moved the axle adjacent to the laces instead, which works great as you can see in the video after the break.

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Early Electromechanical Circuits

In the days before semiconductor diodes, transistors, or even vacuum tubes, mechanical means were used for doing many of the same things. But there’s still plenty of fun to be had in using those mechanical means today, as [Manuel] did recently with his relay computer. This post is a walk through some circuits that used those mechanical solutions before the invention of the more electronic and less mechanical means came along.

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Tesla Vs. Edison

The phrase “Tesla vs. Edison” conjures up images of battling titans, mad scientists, from a bygone age. We can easily picture the two of them facing off, backed by glowing corona with lightning bolts emitting from their hands. The reality is a little different though. Their main point of contention was Tesla’s passion for AC vs. Edison’s drive to create DC power systems to power his lights. Their personalities also differed in many ways, the most relevant one here being their vastly different approaches to research. Here, then, is the story of their rivalry.

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Illuminated arcade spinners

Awesome Illuminated Arcade Spinner

[Tinker_on_Steroids] made some awesome looking spinners that not only light up when spun but are a really professional looking build on their own. Before we’d watched his assembly video we were sure he’d just added on to something he’d bought, but it turned out it’s all custom designed and made.

In case you’ve never played the old arcade games, a spinner is an input device for games such as Tempest or Breakout where you rotate a knob in either direction to tell the game which way and how fast to move something. In Tempest you rotate something around the middle of the screen whereas in Breakout you move a paddle back and forth across the bottom of the playing field.

He even detects rotation with a home-made quadrature encoder. For each spinner, he uses two ITR9608 (PDF) optical switches, or opto-interrupters. Each one is U-shaped with an LED in one leg of the U facing a phototransistor in the other leg. When something passes between the two legs, the light is temporarily blocked and the phototransistor detects it i.e. the switch turns off. When the thing moves away, the light is unblocked and it turns on again. The direction of movement is done by having the thing pass between two ITR9608’s, one after the other. The “things” that pass between are the teeth of a 3D printed encoder wheel. Continue reading “Awesome Illuminated Arcade Spinner”

4-way or 8-way joystick mod

4-way Or 8-way Joystick Restrictor Mod

Having a restricted 4-way or 8-way digital joystick for an arcade game is fine if the joystick is built into a game cabinet that plays only one game — 4-way for Pacman and 8-way for Super Cobra. But [Tinker_On_Steroids] wanted a joystick that could be restricted as either 4-way or 8-way for a cabinet that could play a multitude of games, and it had to switch from one type of restriction to the other automatically based on the selected game.

His digital joystick already came with a plate that can be mounted for either 4-way or 8-way restriction, but it has to be manually screwed in place for one or the other. He removed it and designed two 3D-printable parts, one that is to be mounted firmly to the bottom of the joystick and the other that rotates within the first one. Rotated in one orientation gives 4-way restriction and in the other orientation gives 8-way. That left only attaching a servo to do the rotation. The first video below shows mounting this all to the joystick and demoing the servo using a Teensy. The STL files for the parts are on his Thingiverse project page.

He also shows a simple circuit board he made that has two buttons and two LEDs on it for connecting to the Teensy and controlling the servo. And as an added option he shows how to talk to the Teensy from his desktop computer through USB and control the servo that way. In the second video below he details all that and also does a walk-through of the code he wrote for the Teensy. On the Thingiverse page he provides only the hex file but it’s likely you’d write your own software for interfacing with a game anyway.

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Persistence of vision Death Star

Persistence Of Vision Death Star

Death Stars were destroyed twice in the Star Wars movies and yet one still lives on in this 168 LED persistence of vision globe made by an MEng group at the University of Leeds in the UK. While Death Stars are in high demand, they mounted it on an axis tilted 23.4° (the same as the Earth) so that they can show the Earth overlaid with weather information, the ISS position, or a world clock.

More details are available on their system overview page but briefly: rotating inside and mounted on the axis is a Raspberry Pi sending either video or still images through its HDMI port to a custom made FPGA-based HDMI decoder board.  That board then controls 14 LED driver boards mounted on a well-balanced aluminum ring. All that requires 75W which is passed through a four-phase commutator. Rotation speed is 300 RPM with a frame rate of 10 FPS and as you can see in the videos below, it works quite well.

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