Fail Of The Week: Not All Mold Releases Release All Molds.

January 15, 2016 by Gerrit Coetzee 20 Comments

I’m writing a series of articles on resin casting as an extension to my experiences with the instructions found in the wonderful Guerrilla Guide. However, mistakes were made. Having run out of my usual mold release I went to a back-up jar that was lying around from a casting project long, long ago in a workshop far, far away.

GLUE — Never much for readin’ the nutrition facts myself.

I’m refining a technique of making a mold the quick and dirty way. Everything was going well, the sprues looked good and the master released from the silicone. It was time to do the second half of the mold. As usual I applied a generous amount of mold release. Since it was the first time this mold was to be used I went ahead and did all the proper steps. Rubbing off the dried release and applying a few more coats just to be sure.

I was completely unaware that I was applying mold release designed for urethane molds only. In other words I thoroughly covered my silicone mold in silicone bonding agents. I remained unaware until trying to separate the halves of the mold and found them thoroughly joined. After going through the stages of grief I finally figured out where it all went wrong.

Oh well. I’m ordering some of my regular pick, Stoner A324, and that should do the trick. There’s also Mann- Ease Release 200. While having probably the best name a release agent can have, it doesn’t work as well and needs approximately 100 years to dry. After this setback I’d rather just, grudgingly, learn my lesson and order the correct thing.

I wonder if the smooth-on description can say URETHANE RUBBER a few more times. — Oh. Yes I see. Urethane… Urethane…

So now that we know the right way to fix this is to order the right product, is there a hack to get around it? Does anyone have a homebrew trick for release agent that can be used in a pinch? Leave your comments below.

A Shareable Wireless Biometric Flash Drive

January 15, 2016 by Kristina Panos 4 Comments

Wireless storage and biometric authentication are both solved problems. But as [Nathan] and [Zhi] have noticed, there is no single storage solution that incorporates both. For their final project in [Bruce Land]’s ECE 4760, they sought to combine the two ideas under a tight budget while adding as many extras as they could afford, like an OLED and induction coil charging.

Their solution can be used by up to 20 different people who each get a slice of an SD card in the storage unit There are two physical pieces, a base station and the wireless storage unit itself. The base station connects to the host PC over USB and contains an Arduino for serial pass-through and an nRF24L01+ module for communicating with the storage side. The storage drive’s components are crammed inside a clear plastic box. This not only looks cool, it negates the need for cutting out ports to mount the fingerprint sensor and the OLED. The sensor reads the user’s credentials through the box, and the authentication status is displayed on an OLED. Files are transferred to and from the SD card over a second nRF24L01+ through the requisite PIC32.

Fingerprint authorization gives the unit some physical security, but [Nathan] and [Zhi] would like to add an encryption scheme. Due to budget limitations and time constraints, the data transfer isn’t very fast (840 bytes/sec), but this isn’t really the nRF modules’ fault—most of the transmission protocol was implemented in software and they simply ran out of debugging time. There is also no filesystem architecture. In spite of these drawbacks, [Nathan] and [Zhi] created a working proof of concept for wireless biometric storage that they are happy with. Take a tour after the break.
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Ham Radio Public Service Activities – Rewarding And Useful

January 15, 2016 by Rud Merriam 19 Comments

“Hi! I’m Rud, Kilo Five Romeo Uniform Delta.” That’s me introducing myself at a ham meeting. Ham radio operators kid that we don’t have last names, we have call signs.

Becoming an Amateur Radio Operator (ARO), our more formal name, is not difficult and opens a world of interesting activities, including hacking. As with anything new, becoming actively involved with an existing club can be daunting. The other hams at a meeting are catching up with their buddies and often seem uninterested in the new guy standing nearby. Some groups will invite new members to stand and introduce themselves early in the meeting, which helps break the ice.

Regardless of how anyone else acts at the meeting there is one ham who is always looking for someone new – the ham who manages public service events, where amateur radio operators help establish communications for large public gatherings. These can be local bike rides, walks, or runs; I’ve even seen hams working an art show. In the nomenclature adopted since 9/11, these are “planned incidents” in contrast to “unplanned incidents” like hurricanes, tornadoes, forest fires, snow storms, and other natural or man made disasters. Working planned incidents is training for unplanned incidents when that need arises. The basic activities for AROs are the same.

Here in the Houston there are two very big events that enlist hundreds of hams. The big one in January is the Houston Marathon. The other large event is the Houston to Austin Multiple Sclerosis 150 (MS 150) mile bike ride in April. That event starts on Saturday morning, takes a break mid-way on Saturday evening, and finally wraps up late on Sunday evening. Starting in the fall there are warm-up events for the Marathon and in the late winter bike rides to prepare riders for the MS-150. There are also other marathons, Iron Man races, walks, runs, and races throughout the year. Wherever your are, there are probably events nearby and they can always make use of your radio capability.

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Robotic Suitcase Follows You Around

January 15, 2016 by Richard Baguley 64 Comments

I have something that follows me around all the time: my dog Jasper. His cargo-carrying capability is limited, though, and he requires occasional treats. Not so this robotic suitcase. All it needs, the designers claim, is an occasional charge and a Bluetooth device to follow.

Designed by NUA Robotics, this suitcase is equipped with powered wheels and a certain amount of smarts: enough to figure out the direction of a Bluetooth signal such as your cell phone and follow it. This is also accompanied by proximity sensors so it doesn’t bump into you or other people. When the built-in battery runs out, just pop put the handle and pull it yourself, and the regenerative motors will recharge the battery. There’s no indication on price, battery life or how much space is left to actually carry stuff yet, but the designers claim it could be out within the year. As someone who uses a walking stick, this sounds like a great idea. And if they can work out how to get it to walk the dog for me, that would be even better.

Now, who will be the first to build a clone of this in their basement? Bonus points if it’s a two-wheeled self-balancer.

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DIY Laser Lumia Lights Up The Night

January 15, 2016 by James Hobson 20 Comments

Lasers are awesome, and as the technology continues to advance, they keep getting cheaper! If you’ve ever wanted your own laser light show in your man cave, it’s never been easier.

In the 70’s [rgrokett] was a planetarium technician, responsible for building and operating laser shows. Back then, the laser modules were huge and expensive. After being reminded of days gone past, thanks to an article about laser light show operators, he decided to try his own hand at building a Low-cost Laser Lumia Lightshow.

And it couldn’t be easier.

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Smart Mirror Notices You And Turns On

January 14, 2016 by James Hobson 22 Comments

Smart, technology filled bathrooms are inevitably coming, but until then, be the first in your group of friends to make your very own smart mirror!

Gaining popularity in recent months, it’s not that difficult to make a smart mirror. In fact, it’s really just an LCD monitor with a one-way mirror slapped on top. Similar to how Infinity Mirrors work.

The build makes use of an older LCD monitor [Tmonaco189] had laying about. He went to the hardware store and picked up some wood to build a frame that would fit the aspect ratio of the monitor perfectly — and of course to be large enough to cover up the rear casing of the monitor. Once built, it was time to make it smart! Continue reading “Smart Mirror Notices You And Turns On” →

The Stork Looks Different Than We Thought

January 14, 2016 by Bryan Cockfield 26 Comments

What the Internet of Things really needs is more things, and the more ridiculous the better. At least, that’s the opinion of [Eric] who has created a tongue-in-cheek gadget to add to the growing list of connected devices. It’s a Bluetooth-enabled pregnancy test that automatically releases the results to the world. Feeling lucky?

The theory of operation is fairly straightforward. A Bluetooth low-energy module is integrated into the end of a digital pregnancy test. These tests have a set of photo detectors to read the chemical strip after the test is conducted. If the test is positive, the module sends a signal to a Raspberry Pi which tweets the results out for the world to see. It also has an option to send a text message to your mom right away!

[Eric]’s project to live-tweet a pregnancy test also resulted in a detailed teardown of a digital pregnancy test, so if you need any technical specifications for pregnancy tests (for whatever reason) his project site has a wealth of information. He does note that his device can be used on other similar devices with directly driven LCD screens, too. The fun doesn’t end there, though! Once the pregnancy is a little further along you’ll be able to get the baby on Twitter, too.

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