Warning! Vacuum tubes, transformers, capacitors, and amplification circuits described on these pages operate at high voltages that can cause permanent injury, disability or death. Vacuum tubes operate at high temperatures that can cause severe burns. Never attempt to repair, construct, alter, test, work on or touch electronic equipment unless you are trained or otherwise qualified to do so. Likewise, never open or remove a protective cover from electronic equipment unless you are trained or otherwise qualified to do so. This site is for reference only and is not meant for instruction, training, or to provide guidance to someone who desires to build, repair, or otherwise touch electronic equipment.