Month: March 2015

Measure As Little As You Want With OpenQCM

March 31, 2015 by 24 Comments

The clever folks over at [Novaetech SRL] have unveiled openQCM, their open-source quartz crystal microbalance. A QCM measures very minute amounts of mass or mass variation using the piezoelectric properties of quartz crystal. When an object is placed on the surface of this sensor, the changes in the crystal’s resonant frequency can be detected and used to determine its mass in a variety of experimental conditions (air, vacuum, liquid). However, most QCM technology is proprietary and pricey – at least US$3000 for the microbalance itself. Any consumables, such as additional crystals, cost several hundred dollars more.

The openQCM has a sensitivity of 700 picograms. At its core is an Arduino Micro with a custom PCB. The board contains a 10K thermistor for temperature offset readings and the driver for a Pierce oscillator circuit. The quartz crystal frequency is determined by hacking the timer interrupts of the Arduino’s ATmega32u4. An external library called FreqCount uses the clock to count the number of pulses of the TTL signal in a 1 second time frame. This yields quartz crystal frequency resolution of 1Hz. The user interface is built in Java so that data can be read, plotted, and stored on your computer. The entire casing is 3D-printed, and it appears that the sensors are standard oscillator crystals without their cases.

Simplistic design makes assembly and maintenance a breeze. It only weighs 55 grams. Replacing the quartz crystal requires no special tools due to the clip system. The openQCM can be used as a single unit, or in multiples to form a network for all of your precise measurement needs. While they have kits available that will set you back US$500, all of the files and schematics for 3D-printing, assembly, and the PCB are available on the openQCM site for free.

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Fail Of The Week: Easy Cheese? Printer Says No

March 31, 2015 by 39 Comments

Well, this is timely. We saw a lot of things at Midwest RepRap Festival this year on both the printer and the material fronts. We told you about the delicious offerings made possible through remote extruder setups, strong and heavy filaments infused with copper and other metals, and a printer built out of K’NEX. No one was printing with canned cheese, though, and maybe for good reason.

[Andrew] here has created a 3D-printed arm that holds a can of aerosol cheese-like substance in place. A motor causes the holder to move the spout to the side, dispensing the goo. At first he squirts it in a coiled pile on to a cracker. That goes pretty well until it’s time to move away from the cracker. [Andrew]’s later attempt to build up four cheesy walls had us cheering. You can see what we mean after the break.

There are a couple of issues at play. Sometimes the add-on just plain falls off the end of the spout. Other times, air in the can interrupts the flow, just as it does during manual operation. And every once in a while, it just seems that the spout was too close to the substrate.

What do you think about the viability of cheese printing? Would it work better if the extrusion took place remotely, and the cheese was pushed through a thinner tip? Would a cooled print bed help? Let us know.

Continue reading “Fail Of The Week: Easy Cheese? Printer Says No” →

Chinese Whispers For Arduino

March 30, 2015 by 33 Comments

The game of Chinese Whispers or Telephone involves telling one person a sentence, having that person tell another person the same sentence, and continuing on until purple monkey dishwasher. For this year’s Arduino Day, [Mastro] was hanging out at Crunchlab with a bunch of Arduinos. What do you do with a bunch of Arduinos? Telephone with software serial.

The setup for this game is extremely simple – have one Arduino act as the master, listening for bits on the (hardware) serial port. This Arduino then sends those bits down a chain of Arduinos over the software serial port until it finally loops around to the master. The result is displayed in a terminal.

With only about a dozen Arduinos in this game of Telephone, [Mastro] did get a few transmission errors. That’s slightly surprising, as the code is only running at 1200 bps, but the point of this game isn’t to be completely accurate.

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New Part Day: Modern PALs

March 30, 2015 by 46 Comments

Back in the bad old days, if you needed a little bit of custom logic you would whip out a tiny chip known as a PAL. A Programmable Logic Array is just what it sounds like and is the forerunner of modern, unsolderable CPLDs and FPGAs.

PALs and GALs have died off, left to the wastes of the Jameco warehouse, and now it seems the only programmable logic you can buy are huge, 100-pin monstrosities. [Nick] at Arachnid Labs was working on his Tsunami signal generator when a user asked if they could add just one more feature: a programmable divider to count 256 iterations of a clock. This is the perfect application for dumb logic, but if you’re looking for a part that’s not recommended for new designs, you only need to look to old programmable logic.

Enter the Greenpak. [Nick] had a dev kit for these ‘modern PALs’ sitting around and decided to give it a go. They’re small – they max out at 20 pins – but there are a few features that make it a little more interesting than a simple array of AND and OR gates. The Greenpak3 features analog comparators, look-up tables, RC oscillators, counters, and GPIO that will work well enough as circuit glue. They also work at 5V, something you’re just not going to find in more complex programmable logic.

These tiny chips are programmed in a graphical IDE, but the datasheet (PDF) includes full documentation for the bitstream; someone needs to write a Verilog or VHDL compiler for it soon. The one downside with these chips is that they’re tiny; 0.4mm pitch QFN packages. If you can solder that, you’re too good at soldering.

Reverse Engineering An RC Spy Tank

March 30, 2015 by 15 Comments

[Michael] sells a remote control spy tank through his company, and although it’s a toy, there’s an impressive amount of electronics in this R/C tank. It’s controlled from an Android or iDevice over a WiFi connection, something that simply won’t do if you’re trying to sell this to the hacker and maker crowd. The solution to this problem is Wireshark, and with a little bit of work this spy tank can be controlled from just about anything, from a microcontroller via WiFi to a Python app.

Wireshark, everyone’s favorite network packet analysis and capture tool, was used to listen in on the communications between an iPad and the tank. This immediately showed the video stream coming from the camera in the tank, and pointing VLC to the correct port displayed the video.

The motors in the tank were a little trickier, but looking at the data stream, a few packets stood out as being responsible for controlling the motors. After a little experimentation the simple command set was decoded and a Python app whipped up.

These spy tanks are cheap – about $70 from [Michael]’s company and the other usual vendors. It’s not a particularly useful piece of hardware, but someone out there is sure to do something cool with this bit of reverse engineering.

3D printed turtle shell

Take That Mario! 3D Printed Red Tortoise Shell Armor!

March 30, 2015 by 20 Comments

Between all the media coverage of using 3D printers for human prosthetics, some individuals are making a difference for animals too by using 3D printing. And here’s one we really didn’t expect;  a replacement shell for a tortoise!

We’ve all seen the heartwarming articles about pups getting wheels, or dogs getting replacement sprung feet — but is there any love for [Cleopatra] the Tortoise? Canyon Critters Rescue is an animal rescue based out of Golden, Colorado. The founder [Novelli] had recently took in little [Cleopatra] who had a painful and dangerous bone disease where her shell peaks and gets worn out — and without a shell to protect her, could easily become infected. This is typically caused by poor nutrition, so the rescue fixed her diet, but the damage to her shell was already done.

At a public education program for the rescue, [Novelli] made an offhand comment about how cool it would be to 3D print a replacement shell for her to protect the weak spots. Lucky enough for [Cleopatra], someone from the Colorado Technical University was there and wanted to help.

First they 3D scanned [Cleopatra’s] shell, and then created a 3D model of it optimized for 3D printing. They printed miniature test models on a MakerBot, and once satisfied printed the entire thing in 4 pieces. It fits over top of original shell, protecting the weak areas.

It was an incredible learning experience for all involved, and [Novelli] was extremely grateful for the help he received from the community:

I am grateful to all these people volunteering their time and energy to help me. At the rescue I don’t have the resources or funds to do something of this scale.

As for [Cleopatra], she’s living a happy tortoise life once again — and since she’s only in her teens, she has nearly a century of life to look forward to with thanks to 3D printing.

night vision eyedrops

Who Wants Night Vision Eye Drops?

March 30, 2015 by 79 Comments

A team of adventurous biohackers have successfully played with an interesting type of chlorophyll, called Chlorin e6 by putting it in their eyes… and the result? Well, they kind of obtained night vision.

Say what? Chlorin e6 is a chlorophyll analog that is found in deep-sea fish, and has been used to treat night blindness in humans (patent). There’s actually lots of research done with the substance, and it has even been used to treat different cancers — but most of the research was performed on lab rats.

So the team decided to take the next step — [Gabriel Licina] volunteered, and they squirted 50uL of e6 into his wide-stretched eyes. It kicks in after about an hour, so they headed outside at night to test his vision capabilities. They started by identifying basic shapes at 10 meters away, no larger than the size of his hand. Then they tried even larger distances. They had people stand at a tree line in different places, and [Gabriel] standing 50 meters away was able to point them out. The control group could barely identify them even a third of the time.

They’ve published a research paper on their findings, and it’s quite the interesting read. Perhaps in the future this can be manufactured in eye drop form for special use cases like hunting, military, or even search and rescue.

[via reddit]