~ 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.

Circuit Sage offers free design routines and tools for analog and RF circuit engineers, covering topics like PLL design, LNA/PA design, impedance matching, bandgap references, and transmission lines. The site provides Mathcad-based calculation routines that serve as practical references for IC and wireless circuit design work.

Mostly DIY RF is a specialized resource for amateur radio builders, offering PCB kits and detailed documentation for RF circuits including IF amplifiers, low-pass filters, VFOs, crystal filters, and MMIC amplifiers. The site covers designs by well-known ham radio engineers like Hayward and Kopski, making high-performance transceiver building accessible to hobbyists.

Don Klipstein's sprawling technical resource covers everything from LEDs and fluorescent lamps to Tesla coils, xenon strobes, lasers, and high voltage experiments. With decades of accumulated hobbyist knowledge, detailed guides, and regularly updated content, it's an indispensable reference for electronics enthusiasts interested in lighting and discharge lamp technology.

RF Cafe is a comprehensive resource for RF and electronics engineers, offering formulas, reference data, vintage magazine archives, software tools, forums, and a massive parts and services directory. Running since 1996, the site blends technical depth with nostalgia, featuring scanned articles from classic publications like QST, Popular Electronics, and Radio-Craft alongside modern engineering utilities.

A comprehensive free electronics and electrical engineering reference hub covering everything from basic electricity and Ohm's Law to advanced RF design, DSP, amateur radio, and circuit simulation. With hundreds of curated links, formulas, tutorials, data sheets, and calculators organized across multiple phases of learning, it serves as a structured self-study guide for electronics enthusiasts and engineers alike.

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.

Stavros Korokithakis documents his maker and DIY electronics projects, including building a custom $8 voice note recorder inspired by a discontinued pebble device. The blog blends technical tinkering with self-deprecating humor, making it an entertaining read for hobbyist electronics builders and software developers alike.

ChaN's personal electronics engineering site showcases hobby projects, technical notes, and software tools shared with enthusiasts worldwide, including the widely-used FatFs filesystem module for embedded systems. The site blends circuit designs, fluorescent lamp ballasts, and downloadable code under a Creative Commons license, making it a genuine resource for hardware hobbyists.

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.