Author: Zoe Skyforest

3718 Articles

A Simple Sun Tracker With Very Few Parts

July 25, 2021 by 60 Comments

There are a huge number of ways to track the sun if you have some reason to do so. You can use time-based algorithms, or feed in coordinates from the Internet, or you could do it with minimal parts and no electronic processing at all. The latter is how this project from [3D Printer Academy] works. 

One key thing about this project is that you shouldn’t be fooled by the solar panels. They’re not here to generate power for external use. Instead, they’re wired up in opposing polarities to a DC gear motor. The motor turns the panel assembly. As one panel is hit by the sun, it turns the assembly to bring the other panel into the sun as well simply by applying a DC voltage to the motor. The other panel is wired up the opposite way, so if it is in the sun, it brings the other panel into alignment as well.

This serves as a very simple planar solar tracker. If you want to track the sun with minimal parts, this is a very easy way to do it. You’ll just need to put whatever you want to actually aim at the sun on top of the assembly. if that happens to be a larger solar panel, it may be cumbersome and another more complex design may be more suitable.

It’s an ingenious and easy way of tracking the sun, even if it’s not immediately apparent how the device would be useful in its current form. If you’ve got an idea how you would use such a mechanism, let us know in the comments.

We’ve seen other solar tracker projects before, too. Video after the break.

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Joker Monitor Keeps An Eye On Hazardous Gas Levels

July 23, 2021 by 12 Comments

The Joker is a popular character in the Batman franchise, and at times uses poisonous gases as part of his criminal repertoire. That inspired this fun project by [kutluhan_aktar], which aims to monitor the level of harmful gases in the air.

The project doesn’t use just one gas sensor, but several! It packs the MQ-2, MQ-3, MQ-4, MQ-6, and MQ-9. This gives it sensitivity to a huge variety of combustible gases, as well as detecting carbon monoxide. The sensors are read by an Arduino Nano, which displays results on an RGB LED as well as an attached IPS screen.

Readings from each sensor can be selected by using an infrared remote. In order to best work as a safety device, however, it could be more useful to have the Arduino automatically cycle through each sensor, checking them periodically and raising an alarm in the event of a high reading.

The whole project is built on a custom PCB which is artfully constructed with an image of the Joker himself. It helps to make the project a bit more of a display piece, and speaks to the aesthetic skills of its creator.

It’s a fun build, and one that could be mighty capable with a few software tweaks. With that said, if you’re working in a space with real hazards from combustible gases, it may be worth investing in some properly rated safety equipment rather than relying on an Arduino project.

Incidentally, if you’d like to improve the results from using such gas sensors, we’ve looked at that in the past. Video after the break.

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A Nerf Ball Turret Complete With FPV

July 23, 2021 by 2 Comments

Sentry turrets have long been a feature of science fiction films and video games. These days, there’s nothing stopping you from building your own. [otjones99] has done just that, with his FPV Nerf Ball launcher.

The system works on the basic principle of launching soft foam balls via a pair of counter-rotating wheels. It’s a remarkably simple way of electrically launching projectiles without a lot of fuss and mucking around, and it works well here. A blower fan is used to gently roll ammunition towards the launcher wheels as required. There’s a hopper-style clip which uses a servo to drop one ball at a time into the launching tube.

An Arduino Uno is responsible for slewing the turret, and handling the firing process. A joystick is fitted with an NRF24L01 radio module to send signals to the Arduino to aim the turret, while an FPV camera mounted on the turret allows the user to remotely see what the turret is aiming at. With a simple pull of the joystick’s trigger, the turret opens fire.

It’s a fun build, and one that shouldn’t do too much damage to anything given the soft pliable nature of the Nerf ammunition. Of course, if you don’t want to aim your turret yourself, you can always go ahead and build yourself an automated sentry gun. Video after the break.

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3D Printed Roller Coaster Looks Pretty Darn Fun

July 23, 2021 by 10 Comments

Rollercoasters are great fun if you can deal with the exhilaration without throwing up or otherwise screaming until you pass out. Of course, the big outdoors ones are a little hard to get to at the moment, what with a pandemic raging outside. However, [3d_coasters] has built a tabletop design that, while it’s too small to ride, is nonetheless quite impressive. (Video, embedded below.)

The coaster is of the launch design. It relies on an elastic cord that is wound up to high tension to launch the train up to speed, with the train then coasting around the rest of the curves on the track. The quality of the modelling is highly impressive, too. The doors at the boarding platform are even actuated to simulate riders boarding the train! Everything is controlled by an Arduino, a handful of micro servos, and a DC motor.

As you might imagine, this project didn’t happen overnight. 600 hours were logged in Fusion 360 developing the track, and slicing the models in Cura for 3D printing took a further 5 hours. The actual printing process itself took 800 hours, not including finishing, so this project certainly isn’t one for the faint of heart. The final model weighs a full 30 lbs.

Believe it or not, we’ve featured 3D printed rollercoasters before, too. Video after the break.

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LEGO Pole Climbers Are Great Study In What It Takes To Go Vertically Upwards

July 23, 2021 by 3 Comments

Climbing a pole with a robot might sound complicated and hard, but it doesn’t have to be. This video from [Brick Experiment Channel] demonstrates multiple methods of doing the job while keeping things simple from a mechanical perspective. (Video, embedded below.)

The first method uses a gravity locking design, where the weight of the battery pack is placed on a lever arm to increase the normal force on the wheels gripping the pole. Increasing the length of the lever arm, reducing the angle of the crawler, or adding grippier tyres can all be used to increase the grip with this design. The final design of this type is able to climb most of the way up an 8 meter flagpole without too much trouble.

The next version uses rubber bands to help add tension to grip the pole. This too works well and makes it to the top of the flagpole. The final build is a circulating design that looks truly wild in action, and winds its way to the top of the flagpole as well.

It’s great to see the experimental method of designing these Lego creations, as well as seeing how they do in the wild. [Brick Experiment Channel] has been featured here before, too.

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A Simple LEGO Automatic Transmission

July 22, 2021 by 9 Comments

The automatic transmission in your average automobile can be a complicated, hydraulic-y thing full of spooky fluids and many spinning parts. However, simpler designs for “automatic” gearboxes exist, like this Lego design from [FUNTastyX].

The build is based around a simple open differential but configured in a unique way. A motor drives what would typically be one of the output shafts as an input. The same motor is also geared what would normally be the main differential input shaft as well. In these conditions, this double-drive arrangement would sum the speed input and lead to a faster rotational speed at the other shaft, which becomes the output.

However, the trick in this build is that the drive going to what would be the usual differential input is done through a Lego slipper clutch. This part, as explained by [TechnicBricks], allows the outer teeth of the gear to slip relative to the shaft once torque demand is exceeded. What this functionally does is that when the output of the “automatic gearbox” is loaded down, the extra torque demand causes the clutch to slip. This then leads to only one input to the differential doing any work, changing the gear ratio automatically.

It’s likely not a particularly efficient gearbox, as there are significant losses through the very simple clutch, we suspect. However, it does technically work, and we’d love to see its performance rated directly against other simple Lego gearbox designs.

It’s a little confusing to explain in text, but the video from [FUNTastyX] does a great job at explaining the principle in just a few minutes. We’ve seen plenty of crazy Lego gearboxes over the years, and we doubt this will be the last. Video after the break.

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Detecting Ripeness In Fruit And Vegetables Via Neural Networks

July 22, 2021 by 11 Comments

Humans have an innate knack for identifying food that is fit to eat. There’s a reason you instinctively enjoy fresh fruit and vegetables, but find maggot-infested rotting flesh offputting, for example. However, we like to automate as much of the food production process as possible so we can do other things, so it’s necessary to have machines sort the ripe and ready produce from the rest at times. [kutluhan_aktar] has found a way to do just that, using the power of neural networks.

The project’s goal is a straightforward one, aiming to detect ripeness in fruit and vegetables by monitoring pigment changes. Rather than use a camera, the project relies on data from an AS7341 visible light sensor, which is better suited to capturing accurate spectral data. This allows a better read of the actual light reflected by the fruit, as determined by the pigments in the skin which are directly related to ripeness.

Sample readings were taken from a series of fruit and vegetables over a period of several days, which allowed a database to be built up of the produce at various stages of ripeness. This was then used to create a TensorFlow model which can determine the ripeness of fruit held under the sensor with a reasonable degree of certainty.

The build is a great example of the use of advanced sensing in combination with neural networks. We suspect the results are far more accurate than could have reasonably be determined with a cheap webcam, though we’d love to see an in-depth comparison as such.

Believe it or not, it’s not the only fruit spectrometer we’ve featured in these hallowed pages. Video after the break.

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