The triode vacuum tube might be nearly obsolete today, but it was a technology critical to making radio practical over 100 years ago. [Kathy] has put together a video that tells the story and explains the physics of the device.
The first radio receivers used a device called a Coherer as a detector, relying on two tiny filaments that would stick together when RF was applied, allowing current to pass through. It was a device that worked, but not reliably. It was in 1906 that Lee De Forest came up with a detector device for radios using a vacuum tube containing a plate and a heated filament. This device so strongly resembled the Fleming Valve which John Fleming had patented a year before, that Fleming sued De Forest for patent infringement.
After a bunch of attempts to get around the patent, De Forest decided to add a third element to the tube: the grid. The grid is a piece of metal that sits between the filament and the plate. A signal applied to the grid will control the flow of electrons, allowing this device to operate as an amplifier. The modification created the triode, and got around Fleming’s patent.
[Kathy]’s video does a great job of taking you through the creation of the device, which you can watch after the break. She also has a whole series on the history of electricity, including a video on the Arc Transmitter which we featured previously.
Continue reading “The History and Physics of Triode Vacuum Tubes”
Released in 1998, the Game Boy camera was a bit ahead of its time. This specialized Game Boy cartridge featured a 128×128 pixel CMOS sensor and took 4-color greyscale photos. The camera even rotated, allowing for selfies years before that word existed.
The fixed lens on this camera meant no zoom was possible. [Bastiaan] decided to address this shortcoming by building a Canon EF Lens Mount. The resulting build looks hilarious, but actually takes some interesting photos.
[Bastiaan] designed the mount using Rhino 3D, and printed it out on a Monoprice 3D printer. After some light disassembly, the mount can be screwed onto the Game Boy Camera. With the massive 70-200 f4 lens and 1.4x extender shown here, the camera gets a max focal distance of just over 3000 mm.
One issue with the Game Boy Camera was the limited options for doing anything with the photos. They could be transferred to other Game Boy Camera cartridges, or printed using the Game Boy Printer. Fortunately, [Brian Khuu] has a modern day solution that emulates the Game Boy Printer using an Arduino. This lets you get PNG files out of the device.
CubeSats are tiny satellites which tag along as secondary payloads during launches. They have to weigh in at under 1.33 kg, and are often built at low cost. There’s even open source designs for these little spacecrafts. Over 800 CubeSats have been launched over the last few years, with many more launches scheduled in the near future.
[Thomas Cholakov] coupled a homemade cloverleaf antenna to a software-defined radio to track some of these satellites. The antenna is built out of copper-clad wire cut to the correct length to receive 437 MHz signals. Four loops are connected together and terminated to an RF connector.
This homebrew antenna is connected into a RTL-SDR dongle. The dongle picks up the beacon signals sent by the satellites and provides the data to a PC. Due to the motion of the satellites, their beacons can be easily identified by the Doppler shift of the frequency.
[Thomas] uses SDR Console to receive data from the satellites. While the demo only shows basic receiving, much more information on decoding these satellites can be found on the SDR Satellites website.
This looks like a fun weekend project, and probably the cheapest aerospace related project possible. After the break, watch the full video explaining how to build and set up the antenna and dongle.
Continue reading “Tracking CubeSats for $25”
There are a bunch of FPGA development boards to choose from, but how many will fit inside your laptop? The PicoEVB is a tiny board that connects to a M.2 slot and provides an evaluation platform for the Xilinx Artix-7 FPGA family.
This minimalist board sports a few LEDs, a PCIe interface, an integrated debugger, on-board EEPROM, and some external connectors for hooking up other bits and pieces. The M.2 connector provides the board with power, USB for debugging, and PCIe for user applications.
A major selling point of this board is the PCIe interface. Most FPGA boards with PCIe will cost over a grand, and will only fit in a large desktop computer. The lower priced options use older FPGAs. The PicoEVB is tiny and retails for $219. Not a bad deal when the FPGA on-board costs nearly $100.
The PicoEVB is also open source. Design files and sample projects can be found on Github.
[Thanks to Adam Hunt for the tip!]
It’s been 25 years since Microsoft released Windows for Workgroups 3.11. To take a trip back to the end of the 16-bit era of operating system, [Yeo Kheng Meng] got WFW 3.11 running on a modern Thinkpad.
To make things difficult, a few goals were set for the project. Obviously, this wouldn’t be much fun in a virtual machine, so those were banned. A video driver would be needed, since WFW 3.11 only supports resolutions up to 640×480 in software. Some basic support for sound would be desirable. Finally, TCP/IP networking is possible in WFW 3.11, so networking hardware would allow access modern internet.
[Yeo Kheng Meng] accomplished all of these goals on a 2009 Thinkpad T400 and throughly documented the process. Some interesting hacks were required, including the design of a custom parallel port sound card based on the Covox Speech Thing. Accessing HTTPS web servers required a man-in-the-middle attack to strip SSL, since the SSL support on WFW 3.11 is ancient and blocked by most web servers today.
If you want your own WFW 3.11 laptop, the detailed instructions will get you there. [Yeo Kheng Meng] has also provided the hardware design for the sound card. You can watch a talk on the process after the break.
Continue reading “Windows for Workgroups 3.11 in 2018”
There’s a few open source options out there for creating electrical schematics. KiCad and Fritzing are two that will take you from schematic capture to PCB layout. However, there’s been limited options for creating wiring diagrams. Often these are created in Microsoft’s Visio, which is neither open source nor well suited for the task.
QElectroTech is an open source tool for drawing these types of diagrams. It consists of two tools: an element editor for creating schematic symbols and a diagram editor for creating your drawings. Libraries of common symbols are also included, along with the IEC 60617 standardized symbols.
Being a schematic editor, QElectroTech does a good job of drawing clean connections between components. Connections are automatically routed at 90 degree angles and are easy to drag around. Systems made up of more than just electrical connections are also a good fit for the software. Here you can see piping and manual valves as well as electronic sensors and actuators all in the same diagram.
Next time you need to document the wiring of something, QElectroTech is a good option to try. It’s been around since 2008 it is under active development, and there are Windows, OSX and Linux version (including a PPA for nightly builds) available.
Polyglots, in computing terms, are files have multiple valid meanings. We’ve seen some amazing examples of polyglot files in releases of The International Journal of PoC||GTFO. One example: a PDF that is also a ZIP, HTML file, and BPG image.
[Vi Grey] was inspired by PoC||GTFO’s release of a PDF/ZIP/NES ROM hybrid file for issue 0x14. Using a different method, [Vi] created a file which is both an NES ROM and ZIP, where the full contents of the ZIP are stored in the NES ROM.
When PoC||GTFO created their NES ROM polyglot, they stuck most the information outside the bounds of the NES ROM. While the file is valid, you’d lose the ZIP archive if it was burnt to a cartridge.
[Vi]’s polyglot is different. Rip it from a real NES cartridge and you get a ZIP file. Unzip it, and you get the source. Compile that source, and you get a valid ZIP file containing the source. Burn that to a cartridge and… hopefully you grok the recursion at this point.
The source and scripts to mangle the polyglot together are up on Github.