Aaron Cake has many electronic circuits and other electronics information in his archive that is online since the 90s. Antique electronics and Parallel Port Programming.
The Schematic Symbol Reference, How To Solder and Desolder helped many electronic beginners in building their Projects. This was a valuable resource in those days even though it appears common today. The internet was used to genuinely share useful learning and ideas.
Some highlights are circuits on Power Supplies, a 120VAC Inverter, FM Transmitter, Automatic Headlight Brightness Switch, Car Alarm and a Wireless Auto Tachometer. see also the Simple Colour Organ and the Solid State Tesla Coil.