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Were tarot card readers deemed non-essential in your part of the world (and do you think they saw it coming?) More than ever, we all need diversions that are for entertainment purposes only. And what better basis for entertainment than a mystical fortune-telling robot that can read your tarot cards?

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.

Split-flap displays are a great choice no matter what you want to show. We’ve seen them used to display everything from the weather to the current Spotify track.

Via r/duino

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.

Not all tools are sharp, and not all clocks are meant to be precise. Here’s a clock for the times that gives you the gist.

It isn’t hard to imagine a scenario where you are stuck at home all day with nothing to do and certain items are in short supply. Sure, bathroom tissue gets all the press, but try buying some flour or a freezer and see how far you get. Plus online shopping has given up on next day delivery for the duration. Not hard to imagine at all. Now suppose your latest self-quarantine project needs a rotary shaft encoder. Not having one, what do you do? If you are [Tech Build] you go all MacGyver on an old printer and pull out a stepper motor.

How does a stepper motor turn into an encoder? Well, that’s the MacGyver part. We are not big fans of the physical circuit diagrams, but it looks like [Tech Build] borrowed (with credit) from an earlier post and that one has a proper schematic.

Looking at [Andriyf1’s] schematic, you can see each coil connects to an op-amp wired as a positive feedback comparator. The result should be a fairly clean square wave from a noisy input. The real trick is how to connect the coils, which depends on how the stepper is wired. If you have a stepper motor of unknown providence, grab your ohmmeter and read how to sort the wires out.

The initial version was on a breadboard, but the final was on a prototyping board. Of course, an Arduino reads the pulses. We love using things for unintended purposes. Speakers and microphones are often interchangeable. Generators and motors, too. Then there’s the paperclip.

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.

If you dig minimalism but think this clock is a bit too vague to read, here’s a huge digital clock made from small analog clocks.

In ridiculous times, it can help to play ridiculous instruments such as the slide whistle to keep your bristles in check. But since spittle is more than a little bit dangerous these days, it pays to come up with alternative ways to play away the days during lockdown life.

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.

Speaking of, did you hear about the effort to raise and restore the remains of her radio room?

We often like to say that if something is worth doing, then it’s worth overdoing. This automatic cat feeder built by [krizzli] is a perfect example of the principle. It packs in far more sensors and functions than its simple and sleek outward appearance might suggest, to the point that we think this build might just set the standard for future projects.

The defining feature of the project is a load cell located under the bowl, which allows the device to accurately measure out how much feed is being dispensed by weight. This allows the feeder to do things such as detect jams or send an alert once it runs out of food, as well as easily adjust how much is dispensed according to the animal’s dietary needs. To prevent any curious paws from getting into the machine while it’s doling out the food, the lid will automatically open and close during the filling process, complete with optical sensors to confirm that it moved as expected.

All of the major components of the feeder were printed out on a Prusa i3 MK3S, and [krizzli] says that the feed hopper can be scaled vertically if necessary. Though at the current size, it’s already packing around a week’s worth of food. Of course, this does depend on the particular feline you’re dealing with.

In terms of electronics, the feeder’s primary control comes from an ESP8266 (specifically, the Wemos D1 Mini), though [krizzli] also has a Arduino Pro Mini onboard so there’s a few more GPIO pins to play with. The food is dispensed with a NEMA 17, and a 28-BYJ48 stepper is in charge of moving the lid. A small OLED on the side of the feeder gives some basic information like the time until the next feeding and the dispensed weight, but there’s also a simple API that lets you talk to the device over the network. Being online also means the feeder can pull the time from NTP, so kitty’s mealtime will always be on the dot.

Over the years we’ve seen an incredible array of automatic cat feeders, some of which featuring the sort of in-depth metrics possible when you’ve got on onboard scale. But we can’t help but be impressed with how normal this build looks. If nothing else, of all the feeders we’ve seen, this one is probably the most likely to get cloned and sold commercially. They say it’s the most sincere form of flattery.

As soon as [pashiran] laid eyes on his first hand-cranked music box, he knew he was in love. Then, he started punching the holes for his first ditty. As the repetitive stress of punching heated up his arm, his love cooled a bit. Annealed by the ups and downs of this experience, he decided to design a machine that can punch the holes automatically.

Soon, [pashiran] found his people — a community of music boxers that transform MIDI files to DXF format, which creates coordinates for CAD software. In [pashiran]’s music puncher, an Arduino MEGA takes a DXF file and bubble-sorts the jumble of x-coordinates. The MEGA conducts a trio of two stepper motors and DC motor. One stepper pushes the paper through on the x-axis, and the other moves the puncher head back and forth across the paper scroll as the y-axis. The DC motor moves the punch up and down.

Now, paired with [Martin] of [Wintergatan]’s method for chaining music box paper together, [pashiran] can write a prog-rock-length opus without fear of repetitive stress injury. And since he’s published the STL and INO files, now you can, too. Watch it punch and play 250 notes worth of “See My Vest” “Be Our Guest” after the break.

There’s more than one way to avoid manually punching all those holes. When [Wintergatan] was wrestling this problem, he inspired the hacker community to create a MIDI-to-laser-cut-stencil solution.

For anyone who’s ever had to make their own tea, steeping it for the right amount of time can be a pain. That’s precisely the problem that the automatic tea brewing robot solves with its painless approach to brewing tea, built by Slovenian electrical engineering student [Kristjan Berce].

You can use the robot by setting a timer on the knob, at which point the robot raises it arm for the tea bag then dips in the water every 30 seconds until the time has passed. At the end of the timer, the bag is raised clear of the cup to end the brewing. It’s a remarkably simple design that almost evokes chindogu (the Japanese art of useless inventions) if not for the fact that the robot actually serves a useful purpose.

The components for 3D printing the robot are available online, consisting of a case, a container for the Arduino-powered electronics, the lever for holding the tea, and the gear that raises the lever up and down. The device also uses an integrated Li-Ion battery with an accessible charging port and integrated BMS. A 35BYJ46 stepper motor and ULN2003 driver are used to move the 3D printed mechanism. The device uses a potentiometer for setting the steeping time between 1 and 9 minutes, and there’s even a buzzer for indicating once the tea is done brewing.

The Gerber and Arduino code files are open-source for any hackers looking to make their own tea brewers; just take care they operate with “deadly punctuality”.

It’s fair to say that building electronic gadgets is easier now than it ever has been in the past. With low-cost modular components, there’s often just a couple dozen lines of code and a few jumper wires standing between your idea and a functioning prototype. Driving stepper motors is a perfect example: you can grab a cheap controller board, hook it up to a microcontroller, and the rest is essentially just software. But recently [mechatronicsguy] wondered if even that was more hardware than was technically necessary to get the job done.

It’s not that he was intentionally looking to make things more complicated for himself, of course. His rationale was entirely economic; if you’re looking to drive a dozen or more stepper motors, even the “cheap” controllers can add up. So he started to wonder if he could skip the controller entirely and connect the stepper motor directly to the digital pins of an Arduino. Generally speaking this is a bad idea, but if you’re careful and are willing to take the risk, [mechatronicsguy] is living proof it’s possible

So what’s the trick to running a whopping seventeen individual stepper motors directly from the digital pins of an Arduino Mega? Well, to start with you’re not going to be running the beefy NEMA 17 motors like you might find in a 3D printer. [mechatronicsguy] is using the diminutive (and dirt cheap) 28BYJ-48, a light duty stepper used in many consumer products. Even with this relatively tiny motor, you need to crack open the case and cut a trace on the PCB to switch it from unipolar to bipolar.

Beyond that, you need to be careful. [mechatronicsguy] reports he’s had success running as many as ten of them at once, but realistically the fewer operating simultaneously the better. This is actually made easier due to the relatively poor specs of the 28BYJ-48 motor; its huge eleven degree step size means its not really susceptible to the same kind of slippage you’d get on a NEMA 17 when powered down. This means you can cut power to all but the actively moving motor and be fairly sure they’ll all stay where you left them.

With as popular as the 28BYJ-48 stepper is, there are several projects this “quick and dirty” method of interfacing could potentially work with. This small “barn door” star tracker is an obvious example, but we’ve also seen some very nice robotic arms built with these low-cost motors which could benefit from the technique.

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.



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