old computers

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.

This Old House's Ross Trethewey explains MERV filter ratings and how air filtration works, then shows how to build a localized DIY air filter, including a box fan with multiple filters.

A This Old House segment where Richard Trethewey installs a heat exchanger that uses waste heat from a central air conditioner to heat a swimming pool.

A guided Wim Hof breathing session of three rounds at a slow pace, building from a 30 second to a 90 second breath hold. An on-screen bubble animation helps you keep the rhythm.

DIY Perks shows how to modify devices that use older USB connectors so they charge and connect over USB Type-C. He solders in a USB-C connector board and works through cases such as dongle-dependent gadgets and a mouse receiver.

An 11-minute guided Wim Hof breathing session built around an expanding and contracting bubble to pace the breath. Wim breathes along with the viewer over ambient sound.

Wim Hof guides viewers step by step through his breathing method, with some explanation of the science he cites behind it. It stresses learning from the source and avoiding unsafe settings.

A 1930s Chevrolet training film explaining the principles and development of the differential gear. It builds the idea step by step from first principles to the finished mechanism.

DIY Perks shows how to turn old or smashed TVs and monitors into realistic artificial window lights, using the backlight and Fresnel lens to simulate distant daylight.

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.