~ Early Web Links ~

DiscoverCircuits.com, run by engineer Dave Johnson P.E., is a massive repository of over 45,000 free electronic circuits and schematics cross-referenced across 500+ categories for engineers, hobbyists, inventors, and students. Online since 2002, it serves as a go-to reference for quick design ideas, circuit solutions, and component resources covering an enormous breadth of electronic applications.

Aaron Cake's extensive collection of electronic circuit schematics covers categories from power supplies and light/laser projects to telephone circuits and sound/radio designs. Each circuit includes printable PCB patterns, community rankings, and user comments, making it a hands-on resource for hobbyist electronics builders.

Vacuumtubes.com, run by Jonathan Oas out of Hartland, MN, is an online storefront selling vacuum tubes, electron tubes, tube testers, tube sockets, and related electronic parts organized into extensive alphabetical tube lists. The inventory spans everything from rare Western Electric and antique tubes to popular audio types like the 12AX7, 6L6, and EL34, making it a go-to source for vintage audio and electronics enthusiasts.

A comprehensive online reference covering the U.S. Navy's NEETS Module 10, this resource walks through wave propagation, transmission lines, and antenna theory with detailed chapters on electromagnetic fields, radio wave propagation, and sound waves. Published by Integrated Publishing, it offers the full technical training manual with options to download as PDF or order in print, making it a valuable reference for electronics students and hobbyists alike.

HobbyProjects.com curates an extensive collection of links to electronics tutorials, circuits, engineering projects, and useful resources for hobbyists at all skill levels. The site also offers its own tutorials covering topics from basic electronics to microcontrollers, along with dictionaries, formulas, and reference materials for electronics enthusiasts.

Jack Orman's AMZ is a deep well of DIY guitar effects pedal knowledge, offering free schematics, project guides, a lab notebook, and a blog covering circuits for fuzzboxes, boosters, overdrives, and more. With decades of content, PCB boards for sale, and downloadable ebooks, it stands as one of the most comprehensive stompbox electronics resources on the old web.

FC's Electronic Circuits is a sprawling hobbyist archive packed with schematics and project descriptions covering everything from solar charge controllers and LED circuits to tube amplifiers, Geiger counters, and amateur radio gear. With dozens of original circuit designs, Arduino projects, and links to related ham radio and electronics builders, this site is a goldmine for DIY electronics enthusiasts.

Tomi Engdahl's ePanorama.net is a vast electronics reference site covering audio circuits, video systems, PCB design, embedded systems, RF, and much more, with hundreds of categorized links and original schematics. The accompanying blog keeps the resource current with news, product tests, IoT coverage, and cleantech topics, making it a go-to hub for electronics hobbyists and engineers alike.

KA7OEI is Clint's technically-focused amateur radio and electronics blog, covering hands-on modifications and experiments with devices like the MFJ-5008 parabolic ultrasonic receiver. This particular post dives deep into improving the sensitivity and frequency response of the discontinued ultrasonic tool, with detailed photos, circuit analysis, and practical applications like bat detection and power line fault finding.

Bob Robertson's hobby site is a sprawling reference on solar power, covering everything from basic definitions and how solar panels work to educational guides for kids and van-life solar setups. With dozens of articles on renewable energy topics, it reads like a one-man encyclopedia built by a retiree passionate about the subject.