[Eric] Talks Crystal Radios

January 28, 2020 by 42 Comments

The AM broadcast band doesn’t have a lot of mainstream programming on it across much of the United States today. That’s a shame because a lot of kids got their first taste of radio and electronics by building simple crystal radios. [Eric Wrobbel] has a well-done page discussing some of the crystal radio kits and toys that have been around.

[Eric] should know, as he’s written two books on toy crystal radios. The pictures range from a 1945-era “Easy Built Radio Kit” which looks like a piece of masonite with a coil, some Fahnestock clips, and a cat whisker, to a very slick looking Tinymite from 1949. Honestly, though, the one we really want is the X-50 Space Helmet Radio that comes in a box marked “For Young Moon Travelers.”

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ESP32-Cam Does Time Lapse

January 28, 2020 by 21 Comments

Just a few years ago, had someone asked you how much a digital camera with WiFi would cost, you probably wouldn’t have said $6. But that’s about how much [Bitluni] paid for an ESP32-CAM. He wanted to try making the little camera do time lapse, and it turns out that’s pretty easy to do.

Of course, the devil is in the details. The camera starts out needing configuration on the USB interface and that enables the set up of Arduino integration and WiFi configuration. Because it stores each frame of the image on an SD card, the board can’t take rapid-fire pictures. [Bitluni] reports a 3-second delay was about the shortest he could manage, but for most purposes, he was using at least ten seconds.

The program has a live preview window to help you set up the shot, but before your recordings start that should be turned off so as not to overload the little processor and the I/O buses. The result is a bunch of JPG images that you can easily convert to a video on a PC if you wish.

This might be a good way to fit a camera on a 3D printer, especially if the time lapse effect was desired. Otherwise, you might sync to a layer change. Now all [bitluni] needs is an orbital rig.

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Flicker Detector Lets You Hear What You Can’t See

January 28, 2020 by 58 Comments

Have you ever looked at modern LED lighting and noticed, perhaps on the very edge of your perception, that they seemed to be flickering? Well, that’s because they probably are. As are the LEDs in your computer monitor, or your phone’s screen. Pulse width modulation (PWM) is used extensively with LEDs to provide brightness control, and if it’s not done well, it can lead to headaches and eyestrain.

Looking to quantify just how much flashing light we’re being exposed to, [Faransky] has created a simple little gadget that essentially converts flashing light into an audio tone the human ear can pick up. Those LEDs might be blinking on and off fast enough to fool our eyes, but your ears can hear frequencies much higher than those used in common PWM solutions. In the video after the break, you can see what various LED light sources sound like when using the device.

The electronics here are exceptionally simple. Just connect a small solar panel to an audio amplifier, in this case the PAM8403, and listen to the output. To make it a bit more convenient to use, there’s an internal battery, charger circuit and USB-C port; but you could just as easily run the thing off of a 9 V alkaline if you wanted to build one from what’s already in the parts bin.

Who knows? If you carry this thing around long enough, you might even hear the far less common binary code modulation in action (but probably not).

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Factory Laptop With IME Disabled

January 28, 2020 by 36 Comments

Unfortunately not all consumers place high value on the security of their computers, but one group that tends to focus on security are businesses with a dedicated IT group. When buying computers for users, these groups tend to have higher demands, like making sure the Intel Management Engine (IME) has been disabled. To that end, Reddit user [netsec_burn] has outlined a pretty simple method to where “normal people” can purchase one of these IME-disabled devices for themselves.

For those unfamiliar with the IME, it is a coprocessor on all Intel devices since around 2007 that allows access to the memory, hard drive, and network stack even when the computer is powered down. Intel claims it’s a feature, not a bug, but it’s also a source of secret, unaudited code that’s understandably a desirable target for any malicious user trying to gain access to a computer. The method that [netsec_burn] outlined for getting a computer with the IME disabled from the factory is as simple as buying a specific Dell laptop, intended for enterprise users, and selecting the option to disable the IME.

Of course Dell warns you that you may lose some system functionality if you purchase a computer with the IME disabled, but it seems that this won’t really effect users who aren’t involved in system administration. Also note that this doesn’t remove the management engine from the computer. For that, you’ll need one of only a handful of computers made before Intel made complete removal of the IME impossible. In the meantime, it’s good to see that at least one company has a computer available that allows for it to be disabled from the factory.

RF Modulation: Crash Course For Hackers

January 28, 2020 by 16 Comments

When you’re looking to add some wireless functionality to a project, there are no shortage of options. You really don’t need to know much of the technical details to make use of the more well-documented modules, especially if you just need to get something working quickly. On the other hand, maybe you’ve gotten to the point where you want to know how these things actually work, or maybe you’re curious about that cheap RF module on AliExpress. Especially in the frequency bands below 1 GHz, you might find yourself interfacing with a module at really low level, where you might be tuning modulation parameters. The following overview should give you enough of an understanding about the basics of RF modulation to select the appropriate hardware for your next project.

Three of the most common digital modulation schemes you’ll see in specifications are Frequency Shift Keying (FSK), Amplitude Shift Keying (ASK), and LoRa (Long Range). To wrap my mechanically inclined brain around some concepts, I found that thinking of RF modulation in terms of pitches produced by a musical instrument made it more intuitive.

And lots of pretty graphs don’t hurt either. Signals from two different RF dev boards were captured and turned into waterfall and FFT plots using a $20 RTL-SDR dongle. Although not needed for wireless experimentation, the RTL-SDR is an extremely handy debugging tool, even to just check if a module is actually transmitting. Continue reading “RF Modulation: Crash Course For Hackers” →

Open-Source Medical Devices Hack Chat

January 28, 2020 by 5 Comments

Join us on Wednesday, January 29 at noon Pacific for the Open-Source Medical Devices Hack Chat with Tarek Loubani!

In most of the developed world, when people go to see a doctor, they’re used to seeing the latest instruments and devices used. Most exam rooms have fancy blood pressure cuffs, trays of shiny stainless steel instruments, and a comfortable exam table covered by a fresh piece of crisp, white paper. Exams and procedures are conducted in clean, quiet places, with results recorded on a dedicated PC or tablet.

Such genteel medical experiences are far from universal, though. Many clinics around the world are located in whatever building is available, if they’re indoors at all. Supplies may be in chronically short supply, and to the extent that the practitioners have the instruments they need to care for patients, they’ll likely be older, lower-quality versions.

Tarek Loubani is well-versed in the practice of medicine under conditions like these, as well as far worse situations. As an emergency physician and researcher in Canada, he’s accustomed to well-appointed facilities and ample supplies. But he’s also involved in humanitarian relief, taking his medical skills and limited supplies to places like Gaza. He has seen first-hand how lack of the correct tools can lead to poor outcomes for patients, and chose to fight back by designing a range of medical devices and instruments that can be 3D-printed. His Glia Project has free plans for a high-quality stethoscope that can be built for a couple of dollars, otoscopes and pulse oximeters, and a range of surgical tooling to make the practice of medicine under austere conditions a little easier. Continue reading “Open-Source Medical Devices Hack Chat” →

Clock Uses Custom LED Displays To Keep Myst Time

January 28, 2020 by 17 Comments

The Myst fans in the audience will love this project because it displays the 25-hour timekeeping system of the D’ni. The hardware hackers will lean a little closer to their screen because it does so with custom made 25-segment LEDs, and the precision obsessed will start breathing heavily when they hear it maintains an accuracy of 0.001 seconds. As for which of those camps creator [Mike Ando] most identifies with, we can’t say. But we definitely respect his style.

We’ll spare you the in-depth description of the base-25 number system apparently used in the Myst franchise. If you’re interested enough you can click on through to the project’s Hackaday.io page and learn how to actually read the clock. Presumably you’ll then come back here and leave your comment in Klingon.

Let’s instead jump right to the part that really gets us excited, those custom displays. To create them, [Mike] cut the face out of black acrylic with a laser, and filled each void with a mixture of clear resin and very fine gypsum plaster. Getting the mix right can be a little finicky as the plaster can clump up, but the end result diffuses the light nicely. The acrylic front panel and a couple of cardboard “gaskets” to keep the light from leaking onto adjacent segments is then stacked on top of a PCB with corresponding 0603 SMD LEDs.

Beyond the soul-crushing number of wires required to hook everything up internally, the rest of the project is relatively straightforward. It uses a WeMos D1 Mini to connect to the WiFi network and pull the current time down from the geographically closest NTP server every couple of hours. Rather than putting a temperature controlled oscillator on the board, [Mike] has decided to pin his accuracy on a constantly on Internet connection and aggressive synchronizations.

From impressive curved bar graph modules to displays segmented with household items, we’ve seen our fair share of custom indicators. But we have to admit that building 25-segment LED displays for the alphabet of a fictional interstellar species sets the bar pretty high.

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