Repairs You Can Print: Nintendo DS Lite With New Battery And Case

February 17, 2018 by Steven Dufresne 5 Comments

The problem with hanging on to old consumer products is that the original batteries no longer hold a charge. To make matters worse, replacement batteries ordered online have likely been sitting on a warehouse shelf for years and are no better. [Larry G] faced this issue with his old Nintendo DS Lite. Luckily he remembered a hack from his youth where a friend’s Dad had duct-taped a massive alkaline D-cell battery pack to the back of a Gameboy to give it a longer life. And so [Larry] gave new life to his Nintendo DS Lite by designing and 3D printing a case for a battery with an even larger capacity than the original.

He first obtained a 2400 mAh 18650 lithium-ion cell, one with over voltage and under voltage protection. With that as a guide, he designed and 3D printed a case for it made up of four printed parts. The case was needed because the 18650 doesn’t fit in the NDS Lite’s battery compartment. Instead, one of the parts, which he calls the fake battery, fits in the compartment and has copper strips glued to it for connecting to the NDS Lite. From there, wires go to another part wherein sits the 18650. The remaining parts secure it all in place. Charging is done using the NDS Lite’s built-in charger. Even though the new case adds significant bulk, it actually fits well in the hand.

No doubt many of you have your own old NDS Lite sitting around that can benefit from this repair. The project details and STL files can be found on his Hackaday.io page using the above link.

This is also [Larry]’s entry for our Repairs You Can Print contest which puts him in the running for one of two Prusa i3 Mk3s plus the multi-material upgrade.

Slow Down That Hot Rod Camera Dolly

February 16, 2018 by Steven Dufresne 22 Comments

[Eric Strebel] uses a small homemade vehicle with his camera mounted on it to get great tracking shots for the intros to his videos. If the movement is slow enough then the effect is quite professional looking. But he wanted it eight times slower. We not only like the simple way he did it, along with how he machined parts for it, but the result makes it look like a hot rod, hence his name for it, the dolly hot rod. He also has an elegant mechanism for disengaging the motor while he repositions the dolly.

The are many ways to slow down a rotation. We’re assuming he was already at the minimum speed for the vehicle’s 8 RPM motor transmission and electronic speed controller. Gears or pulleys would probably be the next options. But [Eric] went even simpler, switching from roller blade wheels to larger diameter scooter wheels.

As simple as that sounds though, it led to that age-old conundrum, how to attach the wheels to the vehicle. The axle is made up of PVC tubes. So he machined square the ends of some PVC plugs and bolted the plugs to the wheel bearings. That left only to push the PVC plugs into the axle’s tubes. There are a number of ways he could have machined the PVC plugs, and the full explanation of the one he chose is best left to his video below. But basically, it involved first machining a Bondo body filler cylinder with a bolt embedded in it and then using the cylinder to hold onto the PVC plug while he machined that.

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Salyut: How We Learned To Make Space Stations

February 12, 2018 by Steven Dufresne 61 Comments

When you think about space stations, which ones come to mind first? You might think Skylab, the International Space Station (ISS), or maybe Russia’s Mir. But before any of those took to the heavens, there was Salyut.

Russia’s Salyut 1 was humankind’s first space station. The ensuing Salyut program lasted fifteen years, from 1971 to 1986, and the lessons learned from this remarkable series of experiments are still in use today in the International Space Station (ISS). The program was so successful at a time when the US manned space program was dormant that one could say that the Russians lost the Moon but won the space race.

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The Furby Organ

February 12, 2018 by Steven Dufresne 30 Comments

Sometimes you have an idea that is so brilliant and so crazy that you just have to make it a reality. In 2011, [Look Mum No Computer] drew up plans in his notebook for a Furby organ, an organ comprised of a keyboard and a choir of Furbies. For those who don’t know what a Furby is, it’s a small, cute, furry robotic toy which speaks Furbish and a large selection of human languages. 40 million were sold during its original production run between 1998 and 2000 and many more since. Life intervened though, and, [LMNK] abandoned the Furby organ only to recently take it up again.

He couldn’t get a stable note out of the unmodified Furbies so he instead came up with what he’s calling the Furby Forman Fusion Synthesis. Each Furby is controlled by a pair of Ardunios. One Arduino sequences parts inside the Furby and the other produces a formant note, making the Furby sing vowels.

We love the label he’s given for what would otherwise be the power switch, namely the Collective Awakening switch. Flicking it causes all 44 (we count 45 but he says 44) Furbies to speak up while moving their ears, eyes, and beaks. Pressing the Loop switch makes them hold whatever sound they happen to be making. The Vowel dial changes the vowel. But you’ll just have to see and hear it for yourself in the videos below. The second video also has construction details.

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Mini Spy Bug Walkthrough

February 9, 2018 by Steven Dufresne 18 Comments

What we like most about [GreatScott’s] project videos is that he not only shows making them but also the calculations for selecting parts and the modifications along the way. This time he’s made a mini spy bug that records up to nine hours of audio.

His first task was to figure out if the ATmega328p’s ADC is suitable for audio sampling, but only after he explains how sampling works by periodically checking the input voltage from the microphone. Checking the datasheet he found that the ADC’s fastest conversion time is 13 microseconds, which works out to a sampling rate of 76.923 kHz. Good enough.

He then walks through why and how he decided to go with a pre-made amplifier circuit built around the MAX9814 IC. Spoiler alert. His electret’s amplifier output voltage was too low, using an off-the-shelf circuit instead of making his own kept things simple, and the circuit has automatic gain control.

At this point, he added the MicroSD card adapter. Why not just transmit the audio over FM as so many others have done with their hacks? Perhaps he’s worried about someone detecting the transmission and finding his bug.

His final optimization involved getting a good battery life. He measured the circuit’s current draw at 20 milliamps. With a 160 mAh battery capacity, that would be 8 hours of recording time. Removing the Arduino Pro Mini’s voltage regulator and two LEDs got the current down to 18 milliamps and a recording time of 9 hours. Better.

Those are the highlights. Enjoy his full walkthrough in the video below.

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Printed It: Do More With Lockable Ball And Socket Helping Hands

February 8, 2018 by Steven Dufresne 28 Comments

In one hand you hold the soldering iron, in the other the solder, and in two more hands the parts you’re trying to solder together. Clearly this is a case where helping hands could be useful.

Luckily helping hands are easy to make, coolant hoses will do the job at under $10. Attach alligator clips to one end, mount them on some sort of base, and you’re done. Alternatively, you can steal the legs from an “octopus” tripod normally used for cell phones. So why would you 3D print them?

One reason is to take advantage of standardized, open source creativity. Anyone can share a model of their design for all to use as is, or to modify for their needs. A case in point is the ball and socket model which I downloaded for a helping hand. I then drew up and printed a magnifying glass holder with a matching socket, made a variation of the ball and socket joint, and came up with a magnetic holder with matching ball. Let’s takea look at what worked well and what didn’t.

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Delivery Drones Can Learn From Driving And Cycling

February 6, 2018 by Steven Dufresne 10 Comments

Increasingly these days drones are being used for urban surveillance, delivery, and examining architectural structures. To do this autonomously often involves using “map-localize-plan” techniques wherein first, the location is determined on a map using GPS, and then based on that, control commands are produced.

A neural network that does steering and collision prediction can compliment the map-localize-plan techniques. However, the neural network needs to be trained using video taken from actual flying drones. But generating that training video involves many hours of flying drones at street level putting vehicles and pedestrians at risk. To train their DroNet, Researchers from the University of Zurich and the Universidad Politecnica de Madrid have come up with safer sources for that video, video recorded from driving cars and bicycles.

For the drone steering predictions, they used over 70,000 images and corresponding steering angles from the publically available car driving data from Udacity’s Open Source Self-Driving project. For the collision predictions, they mounted a GoPro camera to the handlebars of a bicycle and drove around a city. Video recording began when the bicycle was distant from an object and stopped when very close to the object. In total, they collected 32,000 images.

To use the trained network, images from the drone’s forward-facing camera were fed into the network and the output was a steering angle and a probability of collision, which was turned into a velocity. The drone remained at a constant height above ground, though it did work well from 1.5 meters to 5 meters up. It successfully navigated road lanes and avoided moving pedestrians and bicycles. Intersections did confuse it though, likely due to the open spaces messing with the collision predictions. But we think that shouldn’t be a problem when paired with map-localize-plan techniques as a direction to move through the intersection would be chosen for it using the location on the map.

As you can see in the video below, it not only does a decent job of flying down lanes but it also flies well in a parking garage and a hallway, even though it wasn’t trained for either of these.

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