This page lists some interesting articles that may be of help in designing your own electronic circuits, or troubleshooting others.
Learn about the fundamentals of supply decoupling in digital circuits
A presentation on optimisation of heating directly heated tubes
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....
Reduce 50Hz ripple by balancing the rectifier, by John L. Stewart