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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Load Cells Tell You to Lay Off the Donuts

Our old algebra teacher used to say, “You have to take what you know and use it to get what you don’t know.” That saying always reminds of us sensors that convert physical quantities into things our microcontrollers can measure. Sometimes the key to a project is knowing what kind of sensor will read the physical properties of the system you are interested in. If that physical property is weight, you can use what is known as a load cell. [DegrawSt] uses four 50 kg load cells to create a bathroom scale using an Arduino.

Load cells typically contain strain gauges that change resistance when deformed. This actually measures force, but if you mount them so they measure the force exerted by you standing on a platform, you get a scale. A load cell usually has four strain gauges in a bridge configuration. This causes a voltage across the bridge, although the output can be noisy and on the order of millivolts.

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And the Grandfather of the Year Award Goes to…

Hacker dads often have great plans for all the fun projects they’ll build for their kids. Reality often intrudes, though, creating opportunities for hacker grandfathers who might have more time and resources to tackle the truly epic kid hacks. Take, for instance, [rwreagan] and the quarter-scale model railroad he built for his granddaughter.

Taking inspiration from a 1965 issue of Popular Mechanics, grandpa hit this one out of the park. Attention to detail and craftsmanship are evident from the cowcatcher to the rear coupler of this 4-2-0 steam engine replica, and everywhere along the 275 feet of wooden track — that’s almost a quarter-mile at scale. The locomotive runs on composite wood and metal flanged wheels powered by pair of 350-watt motors and some 12-volt batteries; alas, no steam. The loco winds around [rwreagan]’s yard through a right-of-way cut into the woods and into a custom-built engine house that’ll make a great playhouse. And there are even Arduino-controlled crossbucks at the grade crossing he uses for his tractor on lawn mowing days.

The only question here is: will his granddaughter have as much fun using it as he had building it? We’ll guess yes because it looks like a blast all around. Other awesome dad builds we’ve covered include this backyard roller coaster and a rocketship treehouse.

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Join Hackaday And Tindie At The Southern California Linux Expo

Do you like Open Source? Join Hackaday and Tindie at the largest community-run Open Source conference in North America. We’ll be at the Southern California Linux Expo next week, and we want to see you there.

What’s happening at SCALE this year? Amateur radio license exams, a PGP signing party, Bad Voltage Live and The Spazmatics, and a ton of great talks.

Hackaday and Tindie will be at SCALE Friday through Sunday, showing off the coolest parts of Hackaday, Hackaday.io, and our lovable robotic dog, Tindie. We’ll be handing out t-shirts and stickers, and we’ll be giving tours of the SupplyFrame Design Lab located just two blocks away from the convention center. The Design Lab is a crown jewel of our corporate overlord’s emphasis on Open Hardware, and if you want to see where the magic happens, this is your chance. We’ll be running tours of the Lab on Friday, so find the Hackaday and Tindie crew in the expo area around 3:40 PM.

Here’s something cool: We’re offering discounted SCALE passes, too. They’re 50% off using the code ‘HACK’ at this link. That’s $45 for four days of fun. Continue reading “Join Hackaday And Tindie At The Southern California Linux Expo”

Soda Fridge Hack to Fix a Lazy People Problem

[Paul] participated in a hackathon at work and created a hack to help solve what was ultimately a people problem. A soda fridge at work wasn’t getting refilled when empty. Instead of trying to make people less lazy, [Paul] went with making the fridge more needy.

The first thing [Paul] did was make a soda fridge refill sensor from a scale. As the fridge got emptier, it got lighter. The scale senses that and can decide it’s time for a refill. The only part missing was how to read the output from the scale. To do that, he took an unusual approach.
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Weight Tracking, Wise Cracking IoT Bathroom Scale

For those fighting the battle of the bulge, the forced discipline of fitness bands and activity tracking software might not be enough motivation. Some who are slimming down need a little gentle encouragement to help you lose weight and keep it off. If that sounds like you, then by all means avoid building this weight-tracking IoT scale with an attitude.

Then again, if you live in fear of your scale, [Jamie Bailey]’s version is easy to hate, at least when your numbers are going in the wrong direction. Centered around a second-hand Wii Balance Board talking to a Raspberry Pi via Bluetooth, the scale really only captures your weight and sends it up to InitialState for tracking and feedback. Whether the feedback is in the form of jokes at your expense is, of course, is entirely up to you; if you’d rather get gentle nudges and daily affirmations, just edit a few files. Or if your tastes run more toward “Yo momma so fat” jokes, have at it.

Bathroom scales are a good hacking target, whether it’s reverse engineering a digital scale or eavesdropping on a smart scale. This build is snarky good fun, and if nothing else, it’s good for pranking your roommate. Unless your roommate is your husband or wife, of course. That’s just – no.

Instrumentation Amplifiers and How to Measure Miniscule Change

These days there a large number of sensors and analog circuits that are “controller friendly” meaning that their output signal is easily interfaced to the built-in Analog to Digital Convertors (ADCs) often found in today’s micro-controllers. This means that the signals typically are already amplified, often filtered, and corrected for offset and linearity. But when faced with very low level signals, or signals buried in a larger signal an Instrumentation Amplifier may be what’s needed. The qualities of an Instrumentation Amplifier include:

  • A differential amplifier with high impedance and low bias current on both inputs.
  • Low noise and low drift when amplifying very small signals.
  • The ability to reject a voltage that is present on both inputs, referred to as Common Mode Rejection Ratio (CMRR)

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