Building This TARDIS Is Anything But A Snap

September 23, 2017 by 9 Comments

As an avid fan of the show Dr Who, [Adam Sifounakis] saw a model for a laser-cut TARDIS that piqued his curiosity that eventually grew into a multi-week project involving multiple setbacks, missteps, revamps and — finally — gratification. Behold, his sound activated TARDIS.

First and foremost, assembling and painting the model was a fun puzzle — despite a few trips to the store — with a little backtracking on the painting due to impatience. Next, the creation of a pulsing soft white LED circuit timed with an audio clip to really sell the image of a mini-TARDIS proved to be a tedious ordeal, paying off in the end with a satisfying glow through the vellum-diffused windows on the model.

How to trigger the lights? [Sifounakis] initially wanted a capacitive sensor to trigger the sound effects, but that way lay dragons — and madness — so he went with snap-activated effect to activate the TARDIS like the Doctor himself. After struggling with building his own microphone setup, he switched to an electret mic with adjustable gain which worked like a charm. Setting up this TARDIS’ Adafruit Pro Trinket brain involved a snag or two, and after that it was smooth sailing!

Until he hit another hitch with the power circuit too, that is. Luckily enough, adding a capacitor to give the circuit a bit more juice on boot solved the issue. All that was left to do was dismantle and rebuild his circuit after all this troubleshooting and substitutions, and — finally — install it in his model.

With much satisfaction and a final rework of the LED pulsing effect, it was done. Check it out!

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Scooter Wheels Keep DIY Barn Doors On Track

September 23, 2017 by 6 Comments

[MotoGeeking] built a giant spray booth and is in the process of making customized, air-filtering barn doors for it. When it came to buy hardware to move the doors, though, he found all the ready-made options to be prohibitively expensive. You know what comes next: he designed barn door hardware from the ground up, and did it as cheaply as possible.

After intensely studying many images of barn doors and hardware, [MotoGeeking] decided on the right wheels and went from there. Kick scooter wheels fit the bill nicely, since they are designed to support a lot of weight and come with their own bearings and spacers. And they’re cheap, too — just $9 for a pair.

[MotoGeeking] found some C channel extruded aluminium that seemed to be a perfect match for the wheels, but the wheel was quick to bind whenever it touched the sides. He solved that one by epoxying a length of round bar into the bottom corners. This allows the wheel to move freely while forcing it to stay centered in the track.

In designing the 1/4″ aluminium brackets, [MotoGeeking] took a measure thrice, order once approach to selecting the fasteners. You probably know by now that McMaster-Carr has free CAD drawings for every little thing. [MotoGeeking] imported the ones he liked into Illustrator and built around them. This helped him get it right the first time and kept the headaches and hair-tearing away. Watch the giant door skeleton glide effortlessly on its track after the break.

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Cheap, Full-Duplex Software Defined Radio With The LimeSDR

September 22, 2017 by 43 Comments

A few years ago, we saw the rise of software-defined radios with the HackRF One and the extraordinarily popular RTL-SDR USB TV tuner dongle. It’s been a few years, and technology is on a never-ending upwards crawl to smaller, cheaper, and more powerful widgets. Now, some of that innovation is making it to the world of software-defined radio. The LimeSDR Mini is out, and it’s the cheapest and most capable software defined radio yet. It’s available through a Crowd Supply campaign, with units shipping around the beginning of next year.

The specs for the LimeSDR mini are quite good, even when compared to kilobuck units from Ettus Research. The frequency range for the LimeSDR Mini is 10 MHz – 3.5 GHz, bandwidth is 30.72 MHz, with a 12-bit sample depth and 30.72 MSPS sample rate. The interface is USB 3.0 (the connector is male, and soldered to the board, but USB extension cables exist), and the LimeSDR is full duplex. That last bit is huge — the RTL-SDR can’t transmit at all, and even the HackRF is only half duplex. This enormous capability is thanks to the field programmable RF transceiver found in all of the LimeSDR boards. We first saw these a year or so ago, and now these boards are heading into the hands of hackers. Someone’s even building a femtocell out of a Lime board.

The major selling point for the LimeSDR is, of course, the price. The ‘early bird’ rewards for the Crowd Supply campaign disappeared quickly at $99, but there are still plenty available at $139. This is very inexpensive and very fun — on the Crowd Supply page, you can see a demo of a LimeSDR mini set up as an LTE base station, streaming video between two mobile phones. These are the golden days of hobbyist SDR.

8-Channel ADC For The Raspberry Pi

September 22, 2017 by 10 Comments

The Raspberry Pi is a powerful embedded computing platform. However, for all its Linux-based muscle, it lacks one thing that even the simplest 8-bit microcontrollers usually have – analog-to-digital conversion. There are a great many ways to rectify this shortcoming, and [Chris Burgess] has brought us another – with an 8-channel ADC for the Raspberry Pi.

For the ADC, [Chris] chose the MCP3008, for its low cost and availability. In this configuration it offers 10-bit resolution and a maximum sampling rate of 200 kilosamples per second. Adafruit has a great guide on working with the MCP3008, too. With such a useful resource to hand, [Chris] was able to spin up a PCB to interface the chip to the Raspberry Pi using SPI. [Chris] took care to try to make the board to the official HAT specifications. As far as the physical aspects go, the board is to spec, however [Chris] omitted the EEPROM required for auto-configuration purposes. That said, the pads are on the board if someone wants to take the initiative to install one.

It’s a tidy build that provides something sorely missing from the Raspberry Pi, for a reasonable cost. [Chris]’s goal was to build something that would enable the measurement of analog sensors for a robot project; we’d love to hear your ideas for potential uses in the comments!

Solar Tide Clock Keeps Track Of The Moon

September 22, 2017 by 1 Comment

Old fashioned tide clocks were an attempt to predict high tide by timing the rising and setting of the moon. When you looked at one you could see how many hours until the next high tide. [rabbitcreek] wanted to make his own version of the tide clock that does a better job of predicting the actual high tide than those old clocks, which were essentially glorified timers tuned to the moon’s phases.

[rabbitcreek] based his the tide prediction software off of [Luke Miller’s] Tide Clock, which applies location-specific adjustments to the standard lunar clock, taking into consideration such factors as the geographic features (basin depth, etc.) that modify the default timing. [Miller]’s Arduino code includes a library of common locations organized by NOAA station number.

[rabbitcreek]’s project consists of a Adafruit Feather board hooked up to a DS3231 RTC breakout and a HS-225BB servo, which turns the clock’s hand. It’s an 180-degree servo, attached to a hacked-down Actobotics gearbox gearing the servo down 2:1 to permit 360 degrees of movement.

He also wanted his creation to be left to operate unattended for years, theoretically — so solar power was a natch. The face of the clock consists of individual wavers of solar panel glued into a huge clock-like array. The solar cells feed into an Adafruit PowerBoost 500, a TPL5111 low power timer breakout, and a LiPo battery for when it’s dark out.

If you’re looking for more solar clocks check out this one that uses capacitors as hour markers.

Making A Gun Without A 3D Printer

September 22, 2017 by 120 Comments

Around four years ago the world was up in arms over the first gun to be 3D printed. The hype was largely due to the fact that most people don’t understand how easy it is to build a gun without a 3D printer. To that end, you don’t even need access to metal stock, as [FarmCraft101] shows us with this gun made out of melted aluminum cans.

The build starts off by melting over 200 cans down into metal ingots, and then constructing a mold for the gun’s lower. This is the part that is legally regulated (at least in the US), and all other parts of a gun can be purchased without any special considerations. Once the aluminum is poured into the mold, the rough receiver heads over to the machine shop for finishing.

This build is fascinating, both from a machinist’s and blacksmith’s point-of-view and also as a reality check for how easy it is to build a firearm from scratch provided the correct tools are available. Of course, we don’t need to worry about the world being taken over by hoards of angry machinists wielding unlicensed firearms. There’s a lot of time and effort that goes into these builds and even then they won’t all be of the highest quality. Even the first 3D printed guns only fired a handful of times before becoming unusable, so it seems like any homemade firearm, regardless of manufacturing method, has substantial drawbacks.

Thanks to [Rey] for the tip!

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Hackaday Prize Entry: HaptiVision Creates A Net Of Vibration Motors

September 22, 2017 by 12 Comments

HaptiVision is a haptic feedback system for the blind that builds on a wide array of vibration belts and haptic vests. It’s a smart concept, giving the wearer a warning when an obstruction comes into sensor view.

The earliest research into haptic feedback wearables used ultrasonic sensors, and more recent developments used a Kinect. The project team for HaptiVision chose the Intel RealSense camera because of its svelte form factor. Part of the goal was to make the HaptiVision as discreet as possible, so fitting the whole rig under a shirt was part of the plan.

In addition to a RealSense camera, the team used an Intel Up board for the brains, mostly because it natively controlled the RealSense camera. It takes a 640×480 IR snapshot and selectively triggers the 128 vibration motors to tell you what’s close. The motors are controlled by 8 PCA9685-based PWM expander boards.

The project is based on David Antón Sánchez’s OpenVNAVI project, which also featured a 128-motor array. HaptiVision aims to create an easy to replicate haptic system. Everything is Open Source, and all of the wiring clips and motor mounts are 3D-printable.

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