How much easier would life be if you could just grab hold of whatever mechanism you wanted to manipulate, move it like you want, and then have it imitate your movements exactly? What if you could give a servo MIDI-like commands that tell it to move to a certain location for a specific duration? Wonder no more, because [peterbiglab] has big-brained the idea into fruition.

With just one wire, an Arduino, and some really neat code, [peter] can get this servo to do whatever he wants. First he tells the Arduino the desired duration in frames per second. Then he grabs the horn and moves it around however he wants — it can even handle different speeds. The servo records and then mimics the movements just as they were made.

The whole operation is way simpler than you might think. As [peterbiglab] demonstrates in the video after the break, the servo knows its position thanks to an internal potentiometer on the motor’s rotor. If you locate the pot output pin on the control board and run a wire from there into an Arduino, you can use that information to calibrate and control the servo’s position pretty easily. There are a ton of possibilities for this kind of control. What would you do with it? Let us know in the comments.

If you want to try this with a bunch of servos at once, might as well build yourself a little testing console.

Via r/duino

It’s great to see people are out there trying to find fun ways to exercise amid the current crisis. Although jumping up and down isn’t great for the knees, it does give decent cardio. But if you don’t have a rope or a puddle, we admit that jumping can lose its bounce pretty fast.

Quarantine has been a game-filled time for [fridaay]. Somewhere between a handful of FPS games, he decided to try to play Google’s offline dinosaur-based side scroller game by making the dinosaur spring over the saguaros whenever he physically jumps in the air. (Video, embedded below.)

Here’s how it works: [fridaay] holds a transmit circuit that consists of an Arduino UNO, an accelerometer module, and an nRF24L01 transceiver, all running on a 9 V battery. Whenever [fridaay] jumps, the accelerometer reads the change in Z and sends it to the receiving circuit, which is just another UNO and nRF. The receiving UNO is connected to a laptop and configured to press the space bar so the dinosaur canters over the cacti.

We’ve never been able to stay alive long enough in the game to see this happen, but apparently you need to crouch at some point in the game. [fridaay] has yet to implement a control for that, but we’re sure he’ll think of something. Jump past the break to see the video, and hit him up if you need the code.

If you have a lot of parts at your disposal, why not make a physical version?

Via r/duino

You are stuck at home quarantined and you want to do some Arduino projects. The problem is you don’t have all the cool devices you want to use. Sure, you can order them, but the stores are slow shipping things that aren’t essential these days. If you want to get a headstart while you are waiting for the postman, check out Wokwi’s Playground. For example, you can write code to drive a virtual NeoPixel 16×16 matrix. There’s even example code to get you started.

There are quite a few other choices in the playground including Charlieplexed LEDs, a keypad, and an LCD. There are also challenges. For example, in the traffic light challenge, you are given code that uses a task scheduler library to implement a traffic light. You have to add a turn signal to the code.

In addition to LEDs in various configurations, the site has some serial bus components, an LCD, a keypad, and a NeoPixel strip. There are also a few tools including an EasyEDA to KiCad converter and a way to share sourcecode similar to Pastebin.

Of course, simulations only get you so far, but the site is a fun way to play with some different I/O devices. It would be very nice if you could compose for the different components together, but you could work your code in sections, if necessary. You can do similar things with TinkerCad circuits. If you want to install software, there’s a simulator for you, too.

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?

Looking to sterilize something? Give it a good blast of the old UV-C. Ultraviolet radiation in the shortest wavelength band breaks down DNA and RNA, so it’s a great way to kill off any nasties that are lurking. But how much UV-C are you using? [Akiba] at Hackerfarm has come up with the NukeMeter, a meter that measures the output of their UV-C sterilizer the NukeBox. It is built around a $2.50 sensor and a $3 Arduino.

The NukeMeter is built around a GUVA-S12SD UV sensor breakout board. This sensor is really designed for UV-A detection, but a quick look at the spec sheet revealed that it is sensitive to UV across all of the bands. So, it can be used as a UV-C sensor if you know how sensitive it is to this particular frequency band.

However, the sensor is not that sensitive to UV-C light, so [Akiba] had to do a bit of minor surgery on the circuitry that surrounds the sensor to tweak the output. The sensor was designed to measure relatively low levels of UV light (such as sunlight), and now they are blasting it with a shedload of radiation, so they have to effectively disable one of the op-amps that normally scales the output up, which involves replacing a couple of resistors. That’s a bit of a pain to do with surface mount components, but it is doable with a steady hand and a small tip soldering iron.

Next, an Arduino takes the voltage output of the sensor and converts it into a light level. The mathematics of how this works are all well detailed in the post, but it isn’t complicated, and the source code is here.

Using this, [Akiba] was able to measure how the lights performed, how quickly they warmed up and how much the light level varies along the length of the fluorescent tube.

One caveat to bear in mind here: [Akiba] designed this to measure the output of the low-pressure mercury vapor lamps they are using at Hackerfarm, which output a very narrow frequency band, peaking at 250 nM. This design would not work for a more broadband output or for one which mixed UV-C with UV-A and UV-B. For that, you would need a more sophisticated design that would probably cost more than $5.

SAFETY NOTE: Don’t mess with UV-C light sources unless you have a good idea of what you are doing and are sure that the light is contained, e.g. in a sealed box, maybe with interlocks. Remember that you also rely on DNA, and inadvertently zapping your own DNA can cause all sorts of unpleasantness.  

We once saw a Romeo and Juliet production where the two families were modern-day mob families with 3-piece suits and pistols. If they made King Richard III set in this week, the famous line might be: “Hand sanitizer, hand sanitizer, my kingdom for hand sanitizer!” Even if you have a supply stashed in your prepper cache, you have to touch the bottle so you could cross-contaminate with other users. Public places often have automatic dispensers to combat this, and now you can too. [Just Barran] shows the device in a video, you can see below.

Sourcing parts for projects is sometimes a problem, but right now we are betting the hand sanitizer will be the hardest component. Of course, the Internet is ripe with homemade brews that may or may not be effective based on beer, grain alcohol, or a variety of other base materials.

[Barran] has a big junk box. so he snagged an Arduino and an ultrasonic sensor. The part that is a little tricky is pulling down the pump. The basic idea is to use a servo motor to pull some fishing line. To engage the bottle, there is a small bit of plastic from a notebook cover and the fishing line goes to both sides of it. One side of the fishing line is fixed and the other is what the servo pulls.

We might have used a solenoid to push the button, but we like the servo method for its simplicity. In the end, it does look like it works well. Changing the bottle out probably requires a little surgery since there is a screw holding the plastic bracket in and you might have to update the fishing line lengths. That might be an impediment for a commercial project, but for your own use, it doesn’t seem like it would be a problem.

Fishing line is more useful than you might think. We’ve even seen it used as belts in 3D printers.

Unless you happen to be from Finland, this is just an all too familiar situation: you’re stuck in an inescapable situation with this one person who is really more of an acquaintance than a friend, and neither of you knows who should say something in hopes of keeping a conversation going. Awkward silence is inevitable, and the longer it lasts, the more excruciating the thought of opening your mouth becomes. Well, consider those days over, thanks to [Jasper Choi] and his friends, who blessed us with the System for Awkward Silence Solution and Interaction Enhancer, or SASSIE.

Built as a laser-cut rotating cylinder, and equipped with a pair of microphones, SASSIE detects and counts the duration of any ongoing silence in the room. Once a pre-defined time limit is reached, it rotates itself to a random direction, symbolically pointing a finger to one of the people present in the room to indicate its their turn to speak now. To break the silence right off the bat, the finger pointing is accompanied by some pre-recorded messages. Unfortunately the audio files exceeded the storage of the Arduino Uno used here, so the responsibilities had to be divided between two Arduinos, arranged with the help of some simple serial communication.

While this is obviously a tongue-in-cheek project, it might just be a welcoming relieve for people with social anxiety, and there is definitely potential to take the idea further. Maybe with some inspiration from this happy robot fellow, a future version might ease the conversation even further by suggesting a topic along the way.

[Lewis] of [DIY Machines] was always on the lookout for that perfect something to hang above the couch. After spending a lot of time fruitlessly searching, he designed and built this awesome shelving unit with recessed lighting that doubles as a huge 7-segment clock.

The clock part works as you probably expect — an Elegoo Nano fetches the time from a real-time clock module and displays it on the WS2812B LED strips arranged in 7-segment formations. There’s a photocell module to detect the ambient light level in the room, so the display is never brighter than it needs to be.

Don’t have a 3D printer yet? Then you may need to pass on this one. Aside from the wood back plane and the electronics, the rest of this build is done with printed plastic, starting with 31 carefully-designed supports for the shelves. There are also the LED strip holders, and the sleeve pieces that hide all the wires and give this project its beautifully finished look.

You may have noticed that the far left digit isn’t a full seven segments. If you’re committed to 24-hour time, you’d have to adjust everything to allow for that, but you’d end up with two more shelves. Given the fantastic build video after the break, it probably wouldn’t take too long to figure all that out.

We like big clocks and we cannot lie. If you have room for it, build something like this blinkenlit beauty.

You don’t have to be an extinct mammal or a Millennial to enjoy the smooth, buttery taste of an avocado. Being psychic on the other hand is definitely an advantage to catch that small, perfect window between raw and rotten of this divaesque fruit. But don’t worry, as modern problems require modern solutions, [Eden Bar-Tov], [Elan Goldberg], and [Mizpe Ramon] built the AvoRipe, a device to notify you when your next avocado has reached that window.

Taking both the firmness and color of an avocado as indicators of its ripeness into account, the team built a dome holding a TCS3200 color sensor as stand for the avocado itself, and 3D printed a servo-controlled gripper with a force sensor attached to it. Closing the gripper’s arms step by step and reading the force sensor’s value will determine the softness the avocado has reached. Using an ESP8266 as centerpiece, the AvoRipe is turned into a full-blown IoT device, reporting the sensor readings to a smartphone app, and collecting the avocado’s data history on an Adafruit.IO dashboard.

There is unfortunately one big drawback: to calibrate the sensors, a set of nicely, ripe avocados are required, turning the device into somewhat of a chicken and egg situation. Nevertheless, it’s a nice showcase of tying together different platforms available for widescale hobbyist projects. Sure, it doesn’t hurt to know how to do each part from scratch on your own, but on the other hand, why not use the shortcuts that are at our disposal to remove some obstacles — which sometimes might include programming itself.