Reusing Motors From Washing Machines

December 20, 2017 by Lewin Day 57 Comments

Big ol’ motors are great when you need to get a big job done, but they can be expensive or hard to source new. However, there’s a source of big, fat, juicy motors right at home for most people – the garden variety washing machine. These motors would usually require a special controller, however [Jerry] is here to show us how to hack the controller that comes with the machine.

The hack begins as [Jerry] decides to gut a Maytag MAH7500 Neptune front loader. Many projects exist that borrow the motor but rely on a seperately sourced variable frequency drive, so the goal was to see if the machine’s original controller was usable. The machine was first troubleshooted using a factory service mode, which spins the drum at a set speed if everything is working correctly.

From there, it was a relatively simple job to source the machine schematics to identify the pinouts of the various connectors. After some experimentation with a scope and a function generator, [Jerry] was able to get the motor spinning with the original controller doing the hard work.

It’s a simple hack, and one that relies on the availability of documentation to get the job done, but it’s a great inspiration for anyone else looking to drive similar motors in their own projects. The benefit is that by using the original motor controller, you can be confident that it’s properly rated for the motor on hand.

Perhaps instead of an induction motor, you’d rather drive a high powered brushless DC motor? This project can help.

How Provably Loaded Dice Lead To Unprovable Cheating

December 18, 2017 by Donald Papp 16 Comments

Here’s a really interesting writeup by [Mike] that has two parts. He shows that not only is it possible to load wooden dice by placing them in a dish of water, but that when using these dice to get an unfair advantage in Settlers of Catan, observation of dice rolls within the game is insufficient to prove that the cheating is taking place.

[Mike] first proves that his pair of loaded dice do indeed result in a higher chance of totals above seven being rolled. He then shows how this knowledge can be exploited by a Settlers of Catan player to gain an average 5-15 additional resource cards in a typical game by taking actions that target the skewed distribution of the loaded dice.

The second part highlights shortcomings and common misunderstandings in current statistical analysis. While it’s possible to prove that the loaded dice do have a skewed distribution by rolling them an arbitrary number of times, as [Mike] and his wife do, it is not possible to detect this cheating in a game. How’s that? There are simply not enough die rolls in a game of Settlers to provide enough significant data to prove that dice distribution is skewed.

Our staff of statistics Ph.D.s would claim that [Mike] overstates his claims about shorcomings in the classical hypothesis testing framework, but the point remains that it’s possible to pass through any given statistical testing process by making the effect just small enough. And we still think it’s neat that he can cheat at Settlers by soaking wooden dice in water overnight.

This isn’t the first time we’ve seen Settlers of Catan at the center of some creative work. There’s this deluxe, hand-crafted reboot, and don’t forget the electroshock-enabled version.

[via Reddit; images from official Catan site]

Machined Lightsaber Pen For A More Civilized Age

December 18, 2017 by Tom Nardi 13 Comments

In an increasingly paperless society, writing implements are becoming an obsolete technology for many of us. Certainly not the kind of thing the average person would think to spend more than a couple bucks on, to say nothing of machining one out of a solid piece of aluminum bar stock. But clearly [Bob] is not most people. He recently dropped us a line about a video he uploaded to his aptly-named YouTube channel “Making Stuff”, where he goes through the steps required to turn raw materials into a writing instrument worthy of a Jedi.

Starting with a piece of aluminum chucked up in the lathe, [Bob] cuts out the iconic ribbed profile of Luke’s saber and fills in the gaps with nothing more exotic than a black Sharpie. He then moves on to the more complex shape of the emitter, and then flips the handle over in the lathe and hollows it out so a brass tube can be inserted.

Somewhat surprisingly, it seems more effort ends up being put into the acrylic “blade” than the aluminum handle itself. A chunk of acrylic is drilled and tapped so that it can be mounted in the chuck, and then turned down into a long cylinder. A tip is then cut in the end, the length of the blade is hollowed out, and finally it gets polished up to a nice shine.

The build is completed by inserting a standard ink pen cartridge down the center of the now completed saber. Surely the pen aficionados will lament that he didn’t attempt to build his own ink cartridge as well, but we think he gets a pass considering the rest of it was made from scratch.

If even a glorious writing instrument such as this isn’t enough to get you to re-learn how to write your name, fear not. Whether you’re making music or capturing flags, we’ve played home to numerous other saber projects; eye-safe or otherwise.

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Powering Your Mining Rig The Right Way

December 17, 2017 by Will Sweatman 36 Comments

It happens to the best of us. We power up our project and immediately run into issues. Be it spotty communication or microcontroller reset or any number of bugs that have us mystified and picking though our code… only to find that it’s a power supply issue. Anyone who has tried doing Raspberry Pi stuff and depended on the USB power from their PC has certainly been bit by this.

It’s the same with larger, more power hungry projects as well. [Nerd Ralph] has been running a mining rig for a few years now, and has learned just how important proper power supply management can be. His strategy involves using interlocks to ensure everything powers up at the same time to avoid feedback problems, running a separate ground wire between all GPU cards and the PSU and running the supplies at 220 for the NA folks.

Be sure to check out [Nerd Ralph’s] blog for more details and tips to power your own mining rig.

Give Workshop Pencils A Flush-Mounted Home

December 15, 2017 by Donald Papp 17 Comments

Pencils and pens are apt to go wandering in a busy workshop if they don’t have a handy storage spot. For most of us a soup can or an old coffee mug does the trick, but for a prettier and more useful holder [Stuff I Made] has a short video demonstrating a storage unit made from an elbow fitting and a scrap piece of plywood. He cuts a plywood disk that is friction-fit into one end of the elbow, then it gets screwed into a wall making an attractively flush-mounted holder in a convenient spot.

With the right joint the bottom of the holder remains accessible, as a 90 degree bend would be no good. With a shallower joint angle, a regular screwdriver can still reach the mounting screw and it’s possible to access the bottom of the holder just in case it needs cleaning or something small falls inside. You can see the process and results in the video embedded below. Not bad for one screw, a spare joint, and a scrap piece of plywood.

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Radiosondes: Getting Data From Upstairs

December 8, 2017 by Dan Maloney 41 Comments

Ever since I first learned about radiosondes as a kid, I’ve been fascinated by them. To my young mind, the idea that weather bureaus around the world would routinely loft instrument-laden packages high into the atmosphere to measure temperature, pressure, and winds aloft seemed extravagant. And the idea that this telemetry package, having traveled halfway or more to space, could crash land in a field near my house so that I could recover it and take it apart, was an intoxicating thought.

I’ve spent a lot of time in the woods over the intervening years, but I’ve never seen a radiosonde in the wild. The closest I ever came was finding a balloon with a note saying it had been released by a bunch of schoolkids in Indiana. I was in Connecticut at the time, so that was pretty cool, but those shortsighted kids hadn’t put any electronics on their balloon, and they kind of left me hanging. So here’s a look at what radiosondes are, how they work, and what you can do to increase your chances of finding one.

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The Incredible Shrinking Coin Cell Battery Pack

December 7, 2017 by Kristina Panos 15 Comments

How’s it going with your project for the coin cell challenge? You can only use a single one, but Hackaday alum [Jeremy S Cook] has a great way to package coin cells into a sleek little power packs whether you need one, two, or even four.

[Jeremy] is building a wireless Wii nunchuk, so he needs a small battery that won’t short out or get punctured in the confines of the controller body. A single coin cell holder is already a bit bulky, and he needs to use two in series. He thought, why not try shrink wrapping them together? The only downside here is that the biggest tube that came with your average heat shrink multi-pack is probably a bit too tight to fit around them, so you might have to buy more (aw, shucks!).

After trying a few ways to make a good connection between the leads and the bare coin cell faces, [Jeremy] settled on generously stripping stranded wire and wrapping the long strands around the end to form a conductive swab. This slides in nicely between the coin cell and preshrunk tube. A little more heat will make a good connection, and some hot glue secures the wires. Click past the break for his build video and the other connection methods he tried. Have you come up with something better? Let us know in the comments.

Stray a bit further from the bench and you might come up with something like this googly eye battery holder we saw a few months ago.

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