Continuing his tradition of making bits of wire and scraps of wood work wonders, [HomoFaciens] is back with a unique and clever design for an electromechanical encoder.
There are lots of ways to build an encoder, and this is one we haven’t seen before. Not intended in any way to be a practical engineered solution, [HomoFaciens]’ build log and the video below document his approach. Using a rotating disc divided into segments by three, six or eight resistors, the encoder works by adding each resistor into a voltage divider as the disc is turned. An Arduino reads the output of the voltage divider and determines the direction of rotation by comparing the sequence of voltages. More resistors mean higher resolution but decreased maximum shaft speed due to the software debouncing of the wiped contacts. [HomoFaciens] has covered ground like this before with his tutorial on optical encoders, but this is a new twist – sort of a low-resolution continuous-rotation potentiometer. It’s a simple concept, a good review of voltage dividers, and a unique way to sense shaft rotation.
Is this all really basic stuff? Yep. Is it practical in any way? Probably not, although we’ll lay odds that these encoders find their way into a future [HomoFaciens] CNC build. Is it a well-executed, neat idea? Oh yeah.
Continue reading “Wheel of Resistors Form Unique Rotary Encoder”
We were trolling around Hackaday.io, and we stumbled on [Barb]’s video series called (naturally enough) “Barb Makes Things“. The plot of her videos is simple — Barb points a time-lapse camera at her desk and makes stuff. Neat stuff.
Two particularly neat projects caught our attention: a mechanical pointy-finger thing and the useful 3D-printing-filament rivets that she used to make it. (Both of which are embedded below.) The finger is neat because the scissor-like extension mechanism is straight out of Wile E. Coyote’s lab.
But the real winners are the rivets that hold it together. [Barb] takes a strand of filament, and using something hot like the side of a hot-glue gun, melts and squashes the end into a mushroom rivet-head. Run the filament through your pieces, mushroom the other end, and you’re set. It’s so obvious after seeing the video that we just had to share. (Indeed, a lot of cheap plastic toys are assembled using this technique.) It’s quick, removable, and seems to make a very low-friction pivot, which is something that printed pins-into-holes tends not to. Great idea!
Continue reading “Barb Makes Mechanical Pokey Finger With Filament Rivets”
Quick: What’s the forward voltage drop on a conducting diode? If you answered something like 0.6 to 0.7 V, you get a passing grade, but you’re going to have to read on. If you answered where
k are device-specific constants to be determined experimentally, you get a gold Jolly Wrencher.
[Jakub] earned his Wrencher, and then some. Because not only did he use the above equation to make a temperature sensor, he did so with a diode that you might have even forgotten that you have on hand — the one inside the silicon of a MOSFET — the intrinsic body diode.
[Jakub]’s main project is an Arduino-controlled electronic load that he calls the MightWatt, and a beefy power MOSFET is used as the variable resistance element. When it’s pulling 20 or 30 A, it gets hot. How hot exactly is hard to measure without a temperature sensor, and the best possible temperature sensor would be one that was built into the MOSFET’s die itself.
There’s a bunch of detail in his write-up about how he switches the load in and out to measure the forward drop, and how he calibrates the whole thing. It’s technical, but give it a read, it’s good stuff. This is a great trick to have up your sleeve.
And if you’re in the mood for more stupid diode tricks, we recommend using them as solar cells or just stringing a bunch of them together to make a thermal camera.
Nitinol is a kind of wire that has a memory. If you heat it, it tries to return to the shape it remembers. [Latheman666] recently posted a video (see below) of a Nitinol engine that uses a temperature differential to generate motion.
[Dr. Alfred Johnson] holds a patent on this kind of motor. The concept sounds simple enough. A Nitnol spring shrinks in hot water and expands in cold. The spring is looped over two pulleys. One pulley is geared so it has mechanical advantage over the other one so that there’s a net torque which moves the hot part of the spring towards the cold side, and feeds more cold spring into the hot water. The cold spring then contracts and the entire process starts again.
We haven’t entirely gotten our heads around the gearing, but it seems plausible. On the other hand, this video was posted on April 1. What say you, Hackaday Commenteers?
Continue reading “Doc Johnson’s Shape Memory Motor”
Minecraft modding has become almost as popular as the block-based game itself, with tons of editors and tools available to create new kinds of blocks, mobs, and weapons. And now, with this mod framework that can talk to an Arduino, modders can build blocks that break out of the Minecraft world to control the real world.
While turning on a light from Minecraft is not exactly new, the way that MCreator for Arduino goes about it is pretty neat. MCreator is a no-code framework for building Minecraft mods, which allows modders to build new game capabilities with a drag and drop interface. The MCreator Arduino toolkit allows modders to build custom Minecraft blocks that can respond to in-game events and communicate with an Arduino over USB. Whatever an Arduino can do – light an LED, sense a button press – can be brought into the game. It’s all open-source and free for non-commercial use, which is perfect for the upcoming STEM-based summer camp season. We can think of some great projects that would really jazz up young hackers when presented through a Minecraft interface.
Continue reading “Control the Real World with an Arduino-Enabled Minecraft Mod”
We’re replacing “holy moley” in our vocabulary. Levitating globs of molten aluminum are that much more amazing. It’s not that we couldn’t believe it would work — we understand the physics after the fact. It’s just that we never would have thought to build an induction forge that can simultaneously melt and levitate a chunk of aluminum. (Video embedded below.)
[imsmoother] has had plans for 3 kW and 10 kW induction heaters online since at least 2011, and we’re wondering how we haven’t covered it before. Anyway, in the video, he’s using the smaller of the two to melt a chunk of aluminum. Continue reading “Flying Balls of Molten Aluminum!”
There are few projects that we see as many iterations of as the pet feeder or the plant waterer. (What is it with you people? Are you all as forgetful as we are?) Still, the fun is in the details of the implementation. Or at least that’s the case with [Emmaanuel]’s cat feeder.
The writeup is split into three parts: the worm-drive, the electronics, and the housing (here in English: worm, electronics, housing). And of course, there’s a video inlined below.
The auger and motor housing make great use of PVC pipe and 3D printing, and the dispenser unit looks quite professional. There’s not all that much to say about the electronics — an Arduino clone, an LCD, and a cheap gear motor do just about what you’d expect.
The CNC’ed case with spring-fit tabs steals the show, however. It’s made out of MDF, which doesn’t take well to screwing or glueing. With carefully routed pins and tabs that have a little spring in them, [Emmaanuel] was able to take the pieces off the mill table and just snap them together. Awesome.
Continue reading “Feeding The Cat, Reinventing the Wheel”