This page lists some files that may be of help in designing your own electronic circuits.

Note: Divide by 2 contains an error: The feedback to pin 2 should come from 6, not from pin 5 as in the document. Will update soon.
Learn about the fundamentals of supply decoupling in digital circuits
A presentation about heating methods
Wiring Colours for Tube Amplifiers
An easy to build divide by 2 circuit. Comes in handy to derive a clocksignal with half the original frequency, to directly clock TDA1541 or TDA1547. Many other applications too....