negative ions

John Scholes builds a depth-first tree-search operator step by step in a Dyalog APL session. It covers higher-order functions and runs the search on the N-Queens problem.

Mathologer shows a simple idea, the commutator, that lets anyone who can solve the first layer design their own full Rubik's cube solution. The same idea carries over to other symmetric twisty puzzles such as the Megaminx.

A 2018 tutorial explaining uBlock Origin's advanced user mode, including how to block scripts and use the dynamic filtering settings. It positions the extension as a replacement for tools like uMatrix.

Technology Connections shows a cheap method for capturing analog video: a composite-to-HDMI upscaler feeding an HDMI capture dongle, aimed at digitizing home movies and VHS tapes.

A 1953 US Navy training film on the basic mechanisms in fire control computers: shafts, gears, cams and differentials. It shows how these mechanical parts compute ship and target firing solutions.

Bisqwit writes a NES emulator in C++ in about 15 minutes of tool-assisted, sped-up coding, narrated with captions. It shows an accurate emulator built with a compile-time generated 6502 instruction table. Part 2 covers compiling and running it.

Anders Brownworth gives a basic visual introduction to blockchain using an interactive web demo, covering SHA256 hashes, blocks, chains, distribution, tokens and coinbase transactions.

A beginner-focused tutorial on freehand knife sharpening with a single stone, aiming for a shaving-sharp edge in about five minutes.

A Harvard Business Review video with tactics for getting better at small talk and enjoying it, such as setting goals, allowing pauses, and starting and ending conversations.

Ben Eater shows how to build logic gates out of transistors, including NOR gates. It is part of his clear hardware-from-scratch teaching style.

Inigo Quilez shows step by step how to build a simple heart shape from mathematics and shaders, with code on Shadertoy. It is an introduction to procedural graphics and signed distance functions.

A short video advising how to handle a police stop by politely refusing searches and not answering questions, citing Fourth and Fifth Amendment rights.

A woodworker shows how his table saw accident happened, why it happened and how to avoid a similar one. He describes severe hand lacerations from a blade contact.

A short walkthrough of a hack that tricks a Brother laser printer into accepting third-party toner by working around its genuine-toner check. It notes this may void the warranty.

A guide to using YouTube's Content ID by claiming your own videos through a distributor, so the claims share revenue with the creator and monetize re-uploads. It credits another creator who pioneered the method.