This fantastic-looking ‘bot stands on the shoulders of [Scott Bezak]’s trailblazing method for easy DIY split-flap displays. Push the rather inviting-looking button on the top, and the flaps start flipping around to find your fortune. Once the fates have aligned, a thermal printer on the front spits out an image of your card along with an interpretation.
It’s obvious that [i_mozy] put quite a lot of effort into this slick machine, and we think the stickers look especially great. All the details of physical tarot card readings are accounted for, including a random number to decide the card’s position, and LEDs to represent the card’s element. Suspend your disbelief and check out the demo/promo video after the break.
If we asked you to rattle off all the tools at your own personal disposal, you’d probably leave your timepieces off the list. But we say clocks are definitely tools — cool tools that come in countless forms and give meaning to endless days.
A clock form we hadn’t considered was that of an actual tool. So we were immeasurably delighted to see [scealux]’s clock made from a measuring tape. At least, the time-telling part of the clock is made from a measuring tape. The case isn’t really from a tape measure — it’s entirely printed, Bondo’d, sanded, and painted so well that it’s quite easy to mistake it for the real thing.
Tightly packed inside this piece of functional art is an Arduino Nano and a DS3231 precision RTC module, which we think is fitting for a tool-based clock. The Nano fetches the time and drives a stepper motor that just barely fits inside. There’s just enough tape wound around the printed hub to measure out the time in increments of one hour per inch. Take 1/16″ or so and watch the demo and brief walk-through video after the break.
Timepieces are cool no matter how simplistic or granular they are. Sometimes its nice not to know exactly what time it is down to the second, and most of the really beautiful clocks are simple as can be. If you didn’t know this was a clock, it would still be fascinating to watch the bearings race around the face.
This clock takes design cues from the Story clock, a visual revolution in counting down time which uses magnetic levitation to move a single bearing around the face exactly once over a duration of any length as set by the user. As a clock, it’s not very useful, so there’s a digital readout that still doesn’t justify the $800 price tag.
[tomatoskins] designed a DIY version that’s far more elegant. It has two ball bearings that move around the surface against hidden magnets — an hour ball and a minute ball. Inside there’s a pair of 3D-printed ring gears that are each driven by a stepper motor and controlled with an Arduino Nano and a real-time clock module. The body is made of plywood reclaimed from a bed frame, and [tomatoskins] added a walnut veneer for timeless class.
In addition to the code, STLs, and CAD files that birthed the STLs, [tomatoskins] has a juicy 3D-printing tip to offer. The gears had to be printed in interlocked pieces, but these seams can be sealed with a solution of acetone and plastic from supports and failed prints.
Thanks to some clever Arduino-driven automation, [Gurpreet] can maintain a safe distance from his slide whistle while interacting with it. Slide whistles need two things — air coming in from the top, and actuation at the business end. The blowing force now comes from a focused fan like the ones that cool your printed plastic as soon as the hot end extrudes it. A stepper motor moves the slide up and down using a printed rack and pinion.
Here’s a smooth touch — [Gurpreet] added a micro servo to block and unblock the sound hole with a cardboard flap to make the notes more distinct. Check out the build video after the break, which includes a music video for “My Heart Will Go On”, aka the theme from Titanic. It’s almost like the ship herself is playing it on the steam whistles from the great beyond.
You probably wouldn’t expect to see somebody making astronomical observations during a cloudy day in the center of a dense urban area, but that’s exactly what was happening at the recent 2019 Philadelphia Mini Maker Faire. Professor James Aguirre of the University of Pennsylvania was there demonstrating the particularly compact Mini Radio Telescope (MRT) project built around an old DirecTV satellite dish and a smattering of low-cost components, giving visitors a view of the sky in a way most had never seen before.
Thanks to the project’s extensive online documentation, anyone with a spare satellite dish and a couple hundred dollars in support hardware can build their very own personal radio telescope that’s capable of observing objects in the sky no matter what the time of day or weather conditions are. Even if you’re not interested in peering into deep space from the comfort of your own home, the MRT offers a framework for building an automatic pan-and-tilt directional antenna platform that could be used for picking up signals from orbiting satellites.
With the slow collapse of satellite television in the United States these dishes are often free for the taking, and a fairly common sight on the sidewalk come garbage day. Perhaps there’s even one (or three) sitting on your own roof as you read this, waiting for a new lease on life in the Netflix Era.
Whether it’s to satisfy your own curiosity or because you want to follow in Professor Aguirre’s footsteps and use it as a tool for STEM outreach, projects like MRT make it easier than ever to build a functional DIY radio telescope.
Point and Shoot
The MRT, and really any radio telescope project like this, is essentially made up of two separate systems: one that provides the motorized aiming of the dish, and the receiver that actually captures the signals. Either system could work independently of the other, but when combined with the appropriate software “glue”, they allow the user to map the sky in radio frequencies.
Obviously, the electronics and mechanical components required to pan an antenna across the sky aren’t terribly complex. If you wanted to keep things really simple and were content with moving in a single axis, you could even do it with a “barn door” tracker. What’s really kicked off the recent explosion of DIY radio telescopes is the RTL-SDR project and the era of low-cost Software Defined Radios (SDRs) it’s inspired.
Unsurprisingly, the MRT also uses an RTL-SDR receiver for processing signals from the Low-Noise Block (LNB) in the dish. Professor Aguirre says that since they are still using the stock DirecTV LNB, the telescope is fairly limited in what it can actually “see”. But it’s good enough to image the sun or pick up satellites in orbit, which is sufficient for the purposes of demonstrating the basic operating principles of a radio telescope.
To move the satellite dish, the MRT is using an Arduino connected to a trio of Big Easy Drivers from Sparkfun. These are in turn connected to the stepper motors in the antenna mount, which are sufficiently geared so they can move the dish around without the need for a counterweight. This makes it an excellent candidate for enclosure inside a dome, which would allow for all-weather observations.
Both the RTL-SDR receiver and the Arduino are connected to a Raspberry Pi, which runs the software for the telescope and provides the interface for the user. The MRT GitHub repository contains all of the various tools and programs created for the project, mostly written in Python, which should provide a useful reference even if you’re not interested in duplicating the telescope’s overall design.
Wandering Through the Sky
When we visited Professor Aguirre, he was attempting to use the MRT to find the Sun. You’d think that a simple enough task in the middle of the afternoon, but thanks to an unbroken layer of steel-gray clouds hanging low in the October sky, Sol was absolutely nowhere to be found with our meager human senses.
As the dish made its slow robotic pans across the sky, we spoke with the Professor about the telescope and the various revisions it went through over the years. Eventually the display lit up, showing a representation of an unusually strong signal, clearly the MRT was hearing something out there. After brief scrutiny, the Professor announced that we hadn’t found the sun; instead, the telescope most likely crossed paths with a geostationary satellite.
It was this raconteur style of discovery that kept visitors to the Mini Radio Telescope enthralled. Nobody expected this hacked together contraption of consumer-grade hardware to discover a new exoplanet or help solve some long-pondered mystery of the cosmos while sitting in a Philadelphia parking lot.
But it was more than capable of pointing out objects tens of thousands of kilometers away while our own eyes couldn’t even figure out where the Sun was. It reaffirmed in a very real way that something was out there, and students both young and old couldn’t help but be fascinated by it.
Part of the joy of owning a dog is feeding it. How often do you get to make another living being that happy? However, sometimes you can’t be there when your best friend is hungry. [El Taller De TD] built an auto dog feeder using an Arduino and stepper motor. The video and links are in Spanish, but if your Spanish is rusty, YouTube’s caption autotranslation isn’t bad and Google Translate can help you with the web site.
The electronics are reasonably simple: an Arduino, a Bluetooth module, and a stepper motor driver. Mechanically, the motor and some PVC pipe are all you need. There’s a small phone application to drive the Bluetooth using App Inventor.
This would be a pretty straightforward first project and — of course — could be useful for any kind of animal. For dog use, we might have hardened the external wires and circuit boards a bit though. In addition there are plenty of things you could do in software, for example you could feed every 8 hours. It seems like you could add a sensor to tell when you are out of food, or perhaps if the food was not feeding for some reason.
We’ve looked at using App Inventor with Bluetooth before and it is pretty easy. We might have been tempted to go with Blynk to have more options for communication, but either way is pretty easy.
If you collect trading cards of any kind, you know that storage quickly becomes an issue. Just ask [theguymasamato]. He used to be really into trading cards, and got back into it when his kids caught the bug. Now he’s sitting on 10,000+ cards that are largely unorganized except for a few that made it into sleeve pages. They tried to go through them by hand, but only ended up frustrated and overwhelmed. Then he found out about [Michael Portera]’s Pi-powered LEGO card sorter and got all fired up to build a three-part system that feeds cards in one by one, scans them, and sorts them into one of 22 meticulously-constructed cardboard boxes.
[theguymasamato]’s card sorter is the last stop for a card after the feeder has fed it in from the pile and the scanner has scanned it. The sorter lazy Susans around on a thrust bearing, which is driven by a 3D printed drive wheel attached to a stepper. The stepper is controlled with an Arduino.
Here’s where it gets crazy: the drive wheel and timing belt are made from the flutes of corrugated cardboard. As in, he used that wavy bit in the middle as gear teeth. Every one of those cardboard teeth is fortified with wood glue, a time-consuming process he vows to never repeat. Instead, [theguymasamato] recommends using shims to shore them up as he did in the card feeder. The whole thing was originally going to be made from cardboard. It proved to be too mushy to support the thrust bearing, so [theguymasamato] switched to MDF.
Right now, the sorter is homed via button press, but future plans for the device include an IR break beam switch. We’re excited for the scanner and can’t wait to see the whole system put together. While [theguymasamato] works on that, position yourself past the break to watch the build video.
It’s been a while since we’ve shown a DIY wire bending machine, and [How To Mechatronics] has come up with an elegant design with easy construction through the use of 3D-printed parts which handle most of the inherent complexity. This one also has a Z-axis so that you can produce 3D wire shapes. And as with all wire bending machines, it’s fun to watch it in action, which you can do in the video below along with seeing the step-by-step construction.
One nice feature is that he’s included a limit switch for automatically positioning the Z-axis when you first turn it on. It also uses a single 12 volt supply for all the motors, and the Arduino that acts as the brains. The 5 volts for the one servo motor is converted from 12 using an LM7805 voltage regulator. He’s also done a nice job packaging the Arduino, stepper motor driver boards, and the discrete components all onto a single custom surface mount PCB.
The bender isn’t without some issues though, such as that there’s no automatic method for giving it bending instructions. You can write code for the steps into an Arduino sketch, which is really just a lot of copy and paste, and he’s also provided a manual mode. In manual mode, you give it simple commands from a serial terminal. However, it would be only one step more to get those same commands from a file, or perhaps even convert from G-code or some other format.
Another issue is that the wire straightener puts too much tension on the wire, preventing the feeder from being able to pull the wire along. One solution is to feed it pre-straightened wire, not too much to ask for since it’s really the bending we’re after. But fixing this problem outright could be as simple as changing two parts. For the feeder, the wire is pulled between copper pipe and a flat steel bearing, and we can’t help wondering whether perhaps replacing them with a knurled cylinder and a grooved one would work as the people at [PENSA] did with their DIWire which we wrote about back in 2012. Sadly, the blog entries we linked to no longer work but a search shows that their instructable is still up if you want to check out their feeder parts.
As for the applications, we can think of sculpting, fractal antennas, tracks for marble machines, and really anything which could use a wireframe for its structure. Ideas anyone?
Stepper motors work by alternating a series of magnets in order to rotate its shaft by a certain angle. When the shaft is manually twisted, these magnets produce an electrical signal in a predictable pattern, which as shown in the video below, can be used as an encoder with the help of an Arduino Uno.
More information, including a circuit diagram and the Arduino code used for the stepper-NeoPixel and stepper-stepper examples can be found here. While the write-up notes that this stepper-encoder won’t work reliably if turned too slowly, it seems to work quite well at the fairly low speed shown in the demonstrations.
I want to tell you how to make incremental encoder from stepper motor. When we turning shaft of stepper motor it works like generator. It generates certain impulses on its coils. After some signal processing, we get same impulses as incremental encoder. This encoder has one problem, it can drop steps if you turning very slowly. But for many applications, it doesn’t matter.
With the June solstice right around the corner, it’s a perfect time to witness first hand the effects of Earth’s axial tilt on the day’s length above and beyond 60 degrees latitude. But if you can’t make it there, or otherwise prefer a more regular, less deprived sleep pattern, you can always resort to simulations to demonstrate the phenomenon. [SimonRob] for example built a clock with a real time rotating model of Earth to visualize its exposure to the sun over the year.
The daily rotating cycle, as well as Earth’s rotation within one year, are simulated with a hand painted plastic ball attached to a rotating axis and mounted on a rotating plate. The hand painting was done with a neat trick; placing printed slivers of an atlas inside the transparent orb to serve as guides. Movement for both axes are driven by a pair of stepper motors and a ring of LEDs in the same diameter as the Earth model is used to represent the Sun. You can of course wait a whole year to observe it all in real time, or then make use of a set of buttons that lets you fast forward and reverse time.