Electronics
45 sites
https://electronics2000.co.uk/
Electronics 2000, created by Simon Carter, is a comprehensive hobby electronics reference packed with online calculators for resistors, capacitors, inductors, Ohm's Law, and more, plus technical data articles, pin-outs, and a beginner's guide. The site also offers downloadable Windows software like Electronics Assistant and an EPE Index, making it a genuinely useful toolkit for hobbyists, students, and engineers alike.
https://tgale.home.xs4all.nl/valves.html
Trevor Gale's comprehensive reference site covers vintage vacuum tubes and valves, offering pinout data, characteristics lists, military-to-commercial conversion tables, repair hints, substitution guides, and circuit diagrams for old receivers and amplifiers. Maintained as a companion to the rec.antiques.radio+phono newsgroup FAQ, it serves as a practical technical resource for both seasoned restorers and newcomers to valve/tube circuitry.
https://mostlydiyrf.com/
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.
http://circuitsage.com/newroutine.html
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.
https://epanorama.net/
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.
https://solarpower.guide/
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.
http://btstream.com/resc.html
Bitstream Technologies curates an extensive directory of electronics resources spanning circuit archives, DSP tools, embedded systems, robotics, PCB design, and IC information. A well-organized link library for engineers and hobbyists, covering everything from FPGA design tools to repair and test equipment references.
http://muzique.com/
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.
https://www.hobbyprojects.com/useful_site_links.html
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.
https://antenna.it/
Giovannini Elettromeccanica is an Italian antenna manufacturing company specializing in HF antenna systems for both military and commercial applications, covering the RF spectrum from 1.5 to 30 MHz. Their product catalog includes log-periodic antennas, broadband wire dipoles, fiberglass masts, antenna rotators, and towers, with research, design, manufacturing, and support services all offered in-house.