knowledge work

Andreas Spiess explains the basic principles of LoRa and LoRaWAN, their pros and cons, link budget and bandwidth. He shows his own gateway and client sending a message to The Things Network.

Ben Eater explains how the PS/2 keyboard interface works, covering its clocked serial protocol and scancodes. He builds up the hardware-level understanding needed to read keypresses.

Ben Eater explains how VGA signals work and builds a breadboard circuit that produces correct sync timing so a monitor recognizes the signal. He then builds toward displaying an image from simple logic chips.

Ben Eater explains how a USB keyboard communicates, covering the electrical interface, bit and packet encoding, packet contents, and a comparison with PS/2.

Ben Eater starts a series building a working computer on breadboards around the 6502 microprocessor. In this first part he gets a 'hello world' running from scratch.

Ben Krasnow of Applied Science explains how electrophoretic e-paper displays work and how he modified the driver firmware and waveform lookup tables of a 4.2-inch panel to reach roughly 3Hz partial refresh. It covers the tweakable constants in the refresh process and touches on colored e-ink microcapsules.

Dave Jones of EEVblog and Richard Stephenson tour the 70m DSS43 dish at the Canberra Deep Space Communication Complex and explain how NASA talks to Voyager 2. It covers the transmitters, receivers and tracking involved.

Marco Baringer's tutorial video on SLIME, the Emacs mode for developing Common Lisp. It demonstrates the interactive workflow of working against a live Lisp image.

Dodoid gives an in-depth look at an SGI Onyx RealityEngine2, a $250,000 graphics supercomputer from 1993, covering its history, a physical overview, a teardown and some demos and games.

Tech Ingredients builds a pair of large Voigt speakers and explains ported, transmission line and horn designs. It tests them in an anechoic chamber and uses constrained layer damping for the enclosure.

Tech Ingredients shows how to make a homemade radiative cooling paint, with a custom liquid panel that cools below ambient temperature outdoors. The video covers the materials and how to apply the paint.

Andrew Huang teaches the basics of music theory in about half an hour, covering intervals, chords and patterns. He stresses understanding how music works over memorizing terminology.

NightHawkInLight shows how to make radiative sky cooling paint from grocery and hardware store materials, including a novel calcium carbonate microsphere synthesis. The paint can cool a surface below ambient air temperature in direct sunlight without electricity.

The first lesson of MangoJelly's FreeCAD 0.20 beginner course, covering setup, preferences and navigation. The series teaches fundamentals through complete workflows such as sketching, Part Design and STL export.

A roughly 45-minute vintage US military instructional film that gives a comprehensive overview of celestial navigation, covering sextant use and the theory behind lines of position.

Ben Eater finishes building a minimal VGA video card from logic circuits. He explains analog RGB signals, stores an image in an EEPROM and builds a simple digital-to-analog converter to display it.

Tech Ingredients shows how to build cheap, high-performance flat-panel speakers using audio exciters on sheet materials such as foam-core board. It explains how distributed-mode speakers work and walks through experiments to find good designs.