Seeing The World Through Depth Sensing Cameras

November 10, 2014 by 12 Comments

The Oculus Rift and all the other 3D video goggle solutions out there are great if you want to explore virtual worlds with stereoscopic vision, but until now we haven’t seen anyone exploring real life with digital stereoscopic viewers. [pabr] combined the Kinect-like sensor in an ASUS Xtion with a smartphone in a Google Cardboard-like setup for 3D views the human eye can’t naturally experience like a third-person view, a radar-like display, and seeing what the world would look like with your eyes 20 inches apart.

[pabr] is using an ASUS Xtion depth sensor connected to a Galaxy SIII via the USB OTG port. With a little bit of code, the output from the depth sensor can be pushed to the phone’s display. The hardware setup consists of a VR-Spective, a rather expensive bit of plastic, but with the right mechanical considerations, a piece of cardboard or some foam board and hot glue would do quite nicely.

[pabr] put together a video demo of his build, along with a few examples of what this project can do. It’s rather odd, and surprisingly not a superfluous way to see in 3D. You can check out that video below.

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Teensys And Old Synth Chips, Together At Last

November 10, 2014 by 25 Comments

The ancient computers of yesteryear had hardware that’s hard to conceive of today; who would want a synthesizer on a chip when every computer made in the last 15 years has enough horsepower to synthesize sounds in software and output everything with CD quality audio? [Brian Peters] loves these old synth chips and decided to make them all work with a modern microcontroller.

Every major sound chip from the 80s is included in this roundup. The Commodore SID is there with a chip that includes working filters. The SN76489, the sound chip from the TI99 and BBC Micro are there, as is the TIA from the Atari consoles. Also featured is the Atari POKEY, found in the 8-bit Atari computers. The POKEY isn’t as popular as the SID, but it should be.

[Brian] connected all these chips up with Teensy 2.0 microcontrollers, and with the right software, was able to control these via MIDI. It’s a great way to listen to chiptunes the way they’re meant to be heard. You can check out some sound samples in the videos below.

Thanks [Wybren] for the tip.

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Wax Motors Add Motion To Your Projects

November 10, 2014 by 19 Comments

[electronicsNmore] has uploaded a great teardown and tutorial video about wax motors. Electric wax motors aren’t common in hobby electronics, but they are common in the appliance industry, which means the motors can be often be obtained cheaply or for free from discarded appliances.

As explained in the video below, wax motors are rather simple devices. A small block of wax is sealed in a metal container with a movable piston. When heated, the wax expands and pushes the piston out. Once the wax cools, a spring helps to pull the piston back in.

The real trick is creating a motor which will heat up without cooking itself. This is done with a Positive Temperature Coefficient (PTC) thermistor. As the name implies, a PTC thermistor’s resistance increases as it heats up. This is the exact opposite of the Negative Temperature Coefficient (NTC) thermistors we often use as temperature sensors. PTC’s are often found in places like power supplies to limit in rush current, or small heating systems, as we have in our wax motor.

As the PTC heats up, its resistance increases until it stops heating. At the same time, the wax is being warmed, which drives out the piston. As you might expect, wax motors aren’t exactly efficient devices. The motor in  [electronicsNmore]’s video runs on 120 VAC. They do have some advantages over solenoid, though. Wax motors provide smooth, slow operation. Since they are resistive devices, they also don’t require flyback diodes, or create the RF noise that a solenoid would.

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Hackaday Prize Finalist: An Un-noodly Spectrometer

November 10, 2014 by 17 Comments

And so we come to the final finalist bio for The Hackaday Prize. In only three days, we’ll know whether [fl@C@]’s RamanPi Spectrometer or one of the four other projects to make it into the finals round will be making it to space, or only Japan.

There are a surprising number of spectrometer projects out there on the Intertubes, but most of these setups only measure the absorption spectrum – literally what wavelengths of light are absorbed by the material being measured. A Raman spectrometer is completely different, using a laser to illuminate the sample, and measuring the scattering of light from the material. It’s work that has won a Nobel prize, and [fl@C@] built one with a 3D printer.

Bio below, along with the final video that was sent around to the judges. If you’re wondering who the winner of The Hackaday Prize is, even I don’t know. [Mike] and a few Hackaday overlords do, but the rest of us will remain in ignorance until we announce the winner at the party we’re having in Munich next Thursday.

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Accurately Measuring Electrical Conductivity

November 10, 2014 by 4 Comments

[Ryan] designed a PCB that lets you easily take readings from a commercial electrical conductivity probe over I2C. Conductivity measurements are great for measuring the salinity of a solution, which is useful for applications like hydroponics. While the probes themselves are a bit pricey (on the order of $50 from eBay), they are very accurate and last a long time.

Commercial conductivity probes contain platinum electrodes to prevent corrosion. The electrodes are excited with an AC signal, which prevents polarization of the solution and avoids chemical reactions at the electrodes. The voltage across the two electrodes is measured while the electrodes are being excited, which is proportional to the conductivity of the solution

[Ryan]’s board generates +/-5v and uses a Wien bridge oscillator to generate a sine wave which excites the outermost electrodes. The voltage across the electrodes is amplified and fed into a MCP3221, an inexpensive 12-bit ADC with an I2C interface. [Ryan] also wrote an Arduino library for the MCP3221 so you can easily get your probe up and running.

 

RFToy Makes Wireless Projects Easier

November 10, 2014 by 7 Comments

[Ray] has created RFToy, a simple gadget to aid in setting up wireless systems with a variety of common radio modules. RFToy is an open source microcontroller board running on an ATmega328. While RFToy is Arduino code compatible, [Ray] chose to ditch the familiar Arduino shield layout for one that makes it easier to install RF modules, and is more handheld friendly.

[RFToy] includes headers for the popular nRF24L01 2.4 GHz transceiver, as well as 433/315 transmitters and receivers found in many low-cost wireless electronic devices. The 128×64 pixel OLED screen and 3 button interface make it easy to set up simple user interfaces for testing new designs.

[Ray] hasn’t broken any new ground here. What he has done is create a simple tool for wireless projects. Anyone who’s worked on a wireless system can tell you that tools like this are invaluable for debugging why your circuit isn’t talking. Is it the transmitter? The receiver? Something else in the power supply circuit?

Check out [Ray’s] demo video after the break. In it, he sniffs, records, and plays back signals from several remote-controlled outlets. [Ray] also has a great demo of sending temperature data back and forth using an nRF24L01.

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Developed On Hackaday: $50k Reached In A Week!

November 10, 2014 by 38 Comments

Around 500 awesome people backed the Mooltipass offline password keeper crowdfunding campaign, raising a total of $50k in less than a week… which is nearly half our goal.

The development team and I would therefore like to thank our readers for their support. We were featured by several electronics websites, which definitely helped spreading the world of open source security devices. Many interesting discussions spawned in either our comments section or official Google Group. One new contributor even started looking into implementing TOTP on the Mooltipass.

Another hot topic was a possible smaller and more powerful Mooltipass v2, implementing other functionalities like U2F and encrypted file storage. You may therefore wonder why we didn’t start with it… the reason is simple: limited resources. Our project is made by (great) non-remunerated contributors who took a lot of their spare time to work on the Mooltipass v1. We therefore preferred working on something we’d be sure we could deliver rather than wasting $4M by making promises. We therefore hope that our crowdfunding campaign might allow an even bigger collaboration around a Mooltipass v2!