With his popular Getting Started in Electronics, and Engineer's Mini-Notebook series and a number of different electronics kits sold at Radio Shack, Forrest Mims inspired countless scientists and engineers. Even though he received no formal academic training in science, Forrest has appeared in 70 magazines and scientific journals. He has worked as a consultant for the National Geographic Society, the National Science Teachers Association, and NASA’s Goddard Space Flight Center. Today, Mims works on many scientific projects including climate change research. He's agreed to answer all your questions about science and engineering. As usual, ask as many as you'd like, but please, one question per post.

When he's not lecturing at Stanford or NASA, Alan Adler is working on brewing the perfect cup of coffee and engineering flying toys. His AeroPress is one of the most popular coffee brewing systems available and one of his Aerobie Pro Rings set the world record for the farthest thrown object at 1,333 feet. Alan has agreed to sit down and answer any questions you may have. As usual, ask as many as you'd like, but please, one question per post.

An anonymous reader writes with this excerpt from The Daily Dot:"On Monday evening, a bill aimed at thwarting the production and distribution of plastic 3-D printed weapons was blocked by Senate Republicans. ... The debate over the new legislation centered around the 1988 Undetectable Firearms Act, which bans the production and distribution of weapons that skirt 'walk through metal detectors.' The act has been renewed on two occasions since its passage. It was due to expire again on the 9th of December. The House voted to renew the bill last week. The rise of 3-D printing has made this year's renewal more complicated in the Senate. Many lawmakers, particularly Democrats, feel the current Undetectable Firearms Act inadequately addresses the rising threat posed by printed plastic weapons."

Arvydas Juskevicius (say that five times fast) is an independent software developer and hardware hacker based in London (which is where I got a chance to talk with him) who's decided to bring the useful LED signalling capabilities of many modern smartphones into the world of desktop or laptop computers. With his £10 BlinkStick kit (£15 pre-assembled), you get a programmable multi-color LED that's about the size of a flash memory key. Deceptively simple -- it's essentially one giant pixel, after all, which might not sound exciting when you have millions of them on a dense display surface. But that LED light is something you can use as a signal for alarms, or to tell you that you have a message from one app while another is at full-screen, or practically anything else that you can devise software to notice and react to. I get the sense that Juskevicius would prefer that people get the kit version, to help spur interest in actually soldering some hardware rather than just plugging it in. If you're allergic to paying in other than U.S. dollars, the BlinkStick is also available from Adafruit Industries. Watch the video below to see it in action.

First time accepted submitter wick3t writes "The Neo900 fundraising campaign has already achieved the milestone of 200 pre-orders which means that mass production is now feasible. This follows a successful first prototype that was showcased at the OpenPhoenux-Hard-Software-Workshop 2013. Their next target is 1000 pre-orders as they aspire to reduce the production costs of each device." For those not familiar, the Neo 900 is an offshoot of the OpenMoko GTA04 designed for use in the popular Nokia N900 case (and, yes, they're fixing the weak usb port).

Zothecula writes "Last August, it looked as if NASA's Kepler space telescope was as good as scrap due to the failure of its attitude control system. Now the space agency proposes what it calls the K2 mission concept, which may fix the problem by using the Sun to regain attitude control and allow Kepler to resume its search for extrasolar planets."

A year after the first schematics were completed and a few months after the first prototype board shipped, Make Play Live has released Improv, the first engineering card for EOMA-68 (EOMA-68 is a specification for modular systems that splits the cpu board from the rest of the system, allowing the end user to use the same core with several devices or upgrade e.g. a tablet without having to pay for a new screen shell). From Aaron Seigo's weblog post: "The hardware of Improv is extremely capable: a dual-core ARM® Cortex-A7 System on Chip (SoC) running at 1Ghz, 1 GB of RAM, 4 GB of on-board NAND flash and a powerful OpenGL ES GPU. To access all of this hardware goodness there are a variety of ports: 2 USB2 ports (one fullsize host, one micro OTG), SD card reader, HDMI, ethernet (10/100, though the feature card has a Gigabit connector; more on that below), SATA, i2c, VGA/TTL and 8 GPIO pins. The entire device weighs less than 100 grams, is passively cooled and fits in your hand. Improv comes pre-installed with Mer OS, sporting a recent Linux kernel, systemd, and a wide variety of software tools. By default it boots into console, so if you are making a headless device you needn't worry about extra overhead running that you don't need. If you are going to hook it up to a screen (or two), then you have an amazing starting point with choices such as X.org, Wayland, Qt4, Qt5 and a full complement of KDE libraries and Plasma Workspaces. Improv takes advantage of the open EOMA68 standard to deliver a unique design: the SoC, RAM and storage live on one card (the 'CPU card'), the feature ports are on a PCB it docks with (the 'feature board'). The two dock securely together with the CPU card sitting under the feature board nestled in a pair of rails; they are undocked from each other by pushing a mechanical ejector button." Check out the specs and pictures. The card is available now for $75. Improv is open hardware, with the schematics licensed under the GPL and available soon.

The reports that Apple was to buy Israeli 3-D sensor maker PrimeSense have turned out to be correct; the BBC reports that Apple has confirmed the purchase, though it is mum both about the price it paid and about where 3D sensors are likely to show up first in the Apple lineup. Also at the Register and Apple Insider, among others.

Nerval's Lobster writes "Scientists have been using everything from supercomputing clusters to 3D printers to virtually recreate dinosaur bones. Now another expert is trying to do something similar with the ancient imperial villa built for Roman emperor Hadrian, who ruled from 117 A.D. to 138 A.D. Hadrian's Villa is already one of the best-preserved Roman imperial sites, but that wasn't quite good enough for Indiana University Professor of Informatics Bernie Frischer, who trained as a classical philologist and archaeologist before being seduced by computers into what evolved into the academic discipline of digital analysis and reproduction of archaeological and historical works. The five-year effort to recreate Hadrian's Villa is based on information from academic studies of the buildings and grounds, as well as analyses of how the buildings, grounds and artifacts were used; the team behind it decided to go with gaming platform Unity 3D as a key part of the simulation."

50000BTU_barbecue writes "I made a comment a few days ago in a story basically saying the oscilloscope is dead. While that's a bit dramatic, I've found that over the last 20 years my oscilloscopes have been 'on' less and less. Instead, I use a combination of judicious voltage measurements, a logic analyzer and a decent understanding of the documentation of the gadget I'm working on. Stuff is just more and more digital and microcontroller-based, or just so cheap yet incredibly integrated that there's no point in trying to work on it. (I'm thinking RC toys for example. Undocumented and very cheap. Doesn't work? Buy another.) While I still do old-school electronics like circuit-level troubleshooting (on old test gear), that's not where the majority of hobbyists seem to be. Yet one thing I keep hearing is how people want an oscilloscope to work on hardware. I think it's just not that necessary anymore. What I use most are two regulated DC lab supplies, a frequency counter, a USB logic analyzer, a USB I2C/SPI master, and a USB-RS-232 dongle. That covers a lot of modern electronics. I have two oscilloscopes, a 100MHz two-channel stand-alone USB unit and a 1960s analog plug-in-based mainframe that is a '70s hacker dream scope. But I rarely use them anymore. What equipment do hardware folks out there use the most? And would you tell someone trying to get into electronics that they need a scope?"

The Raspberry Pi project that we've been fans of for quite a while now has hit a new milestone: Today, they announced that as of the last week in October, the project has sold more than two million boards. Raspberry Pi is anything but alone in the tiny, hackable computer world (all kinds of other options, from Arduino to the x86-based Minnowboard, are out there, and all have their selling points), but the low price, open-source emphasis, and focus on education have all helped the Pi catch on. If yours is one of these 2 million, what are you using it for? (And if you favor some other small system for your own experiments, what factors matter?)

Lucas123 writes "The ATF has been testing 3D printed guns over the past year and, not surprisingly, has found that depending on the thermoplastics, 3D printers and CAD designs used, some can explode on the first attempt to shoot them. The ATF published videos this week of the tests on YouTube showing what looked like a Liberator model of a 3D gun exploding upon being fired. Another model, created with the popular ABS polymer and an advanced printer, could fire as many as 8 shots. The tests were published at a time when a law passed in 1988 banning the sale of guns made entirely of plastic is set to expire next month." I hope they post the videos when they do the same tests on Solid Concepts' 1911.

Daniel_Stuckey writes "At the start of this year, President Obama nicely summed up the grandiose promise of 3D printing — or rather, the hype surrounding it. In his State of the Union address the president suggested the fledgling technology could save manufacturing by ushering in a second industrial revolution. That shout-out inspired a spate of buzzkill blog posts pointing out — rightly enough — that despite its potential, 3D printing is still in its infancy. It's not the panacea for the struggling economy we want it to be, at least not yet. Apparently the naysayers weren't enough to kill the 3D-printing dream, because, with support from the federal government, MakerBot announced its initiative to put a 3D printer in every school in America. The tech startup and the administration are betting big that teaching kids 3D printing is teaching them the skills they'll need as tomorrow's engineers, designers, and inventors." Caveat: Makerbot no longer produces open hardware, and they are pushing proprietary Autodesk software and educational materials as part of the free 3D printer. Makerbot also launched a call for open models of math manipulatives on Thingiverse (you might remember them from elementary school) so that teachers have something useful to print immediately.

Nerval's Lobster writes "Researchers have demonstrated a technique that produces inexpensive, functional electrical circuits that can be printed using about $300 worth of materials and equipment, including generic inkjet printers. The technique, developed by researchers from Georgia Tech, the University of Tokyo and Microsoft Research, allows circuits to be printed onto irregularly-shaped materials or almost anything able to go through the paper feed on a printer designed for consumers. The chief advantage of the technique is the ability to print circuits using silver nanoparticle ink rather than relying on the thermal-bonding technique called sintering, which is time-consuming and can destroy delicate base materials. Researchers were able to print new circuits in about 60 seconds on almost any material that could go through the printer, though resin-covered paper, PET film and glossy photo paper worked best, while sheets of canvas cloth and anything magnetic were ineffective. Once printed using silver ink on flexible base material, the circuits can be attached to existing hardware by simply laying or taping them in place and making connections using conductive tape or conductive glue. (Soldering would destroy the underlying material.)"

First time accepted submitter 192_kbps writes "Mike Clements, a long-haul trucker from West Jordan, Utah, built the largest amateur telescope ever with a whopping 70 inch primary mirror he purchased at auction. The entire telescope is 35 feet tall, 900 pounds, and he hopes to tour it in parks. As a hand-turned Dobsonian the telescope lacks the photographic capacity and tracking required for professional astronomy but the views must be breathtaking." (Are there other compelling candidates out there for "largest amateur telescope ever"? The 71" scope listed by nitesky.org appears to be dormant.)

alphadogg writes "The equipment is big and expensive, with the research costs at almost $500,000. But by just using retail components, Chinese professor Chi Nan has built her own Li-Fi wireless system that can use LED lights to send and receive Internet data. "I bought the lights from Taobao," she said, referring to the Chinese e-commerce site. The professor from Fudan University showed off the technology on Tuesday at the China International Industry Fair in Shanghai. Unlike traditional Wi-Fi routers that use radio signals, Chi's system relies on light to send and receive data wirelessly. Others scientists, especially in the U.K., have also been researching the technology, and dubbed it "Li-Fi". But rather than develop specialized hardware, Chi bought off-the-shelf retail parts to create her system."

rtoz writes "Motorola has announced 'Project Ara,' afree and open hardware platform for smartphones. The purpose of Project Ara is to create a modular smartphone that would allow users to swap hardware components according their own wish. The design for Project Ara consists of an endoskeleton (endo) and modules. The endo is the structural frame that holds all the modules in place. A module can be anything, from a new application processor to a new display or keyboard, an extra battery, a pulse oximeter — or something not yet thought of." Motorola's not the first one to think of such a thing; this project is in cooperation with Phonebloks, which had already been pushing for reusable, reconfigurable phone components.

schwit1 writes "Like something out of a Robert Heinlein novel, students at the University of California, San Diego (UCSD) have built a metal rocket engine using a technique previously confined to NASA. Earlier this month, the UCSD chapter of the Students for the Exploration and Development of Space (SEDS) at the Jacobs School of Engineering conducted a hot fire test for a 3D-printed metal rocket engine at the Friends of Amateur Rocketry launch site in California's Mojave Desert. This is the first such test of a printed liquid-fueled, metal rocket engine by any university in the world and the first designed and printed outside of NASA."

An anonymous reader writes "My wireless router just died. I have an old netbook lying around that has a wired network interface and a wireless one. The wireless card is supported in master mode by Linux, FreeBSD, and OpenBSD. What does Slashdot recommend I use to turn it into a router/wireless access point? DD-WRT? pfSense? Smoothwall? Fedora/Ubuntu/OpenBSD with a manual configuration? I'm not afraid of getting my hands dirty and I know what I'm doing, but I want as close to zero maintenance as possible."

That things are bigger in Texas is sometimes more than just a cliche. A few weeks ago, on the way to LinuxCon, I stopped by what is certainly the biggest hackerspace that I've ever seen; is it the biggest in the world? Whatever the answer is to that, Houston's TX/RX Labs is not just big — it's busy, and booked. Unlike some spaces we've highlighted here before (like Seattle's Metrix:CreateSpace and Brooklyn's GenSpace), TX/RX Labs has room and year-round sunshine enough to contemplate putting a multi-kilowatt solar array in the backyard. Besides an array of CNC machines, 3-D printers, and both wood- and metal-working equipment, TX/RX has workbenches available for members to rent. (These are serious workspaces, made in-house of poured concrete and welded steel tubing.) Member Steve Cameron showed me around, but TX/RX Labs is so large that we broke the tour into two parts, with the other one set to display next week.