Get On Board with. Compass Card. Compass Card is the smart card and smart choice for transit passes in the San Diego region. Compass Card is your ticket for the Bus, TROLLEY, COASTER, and SPRINTER.ompass Card. Compass Card is the smart card and smart choice for transit passes in the San Diego region. Compass Card is your ticket for the Bus, TROLLEY, COASTER, and SPRINTER.
Electron (or Vacuum) Tubes. An electron tube (also known as a 'Vacuum tube', or a 'Valve' ) is a glass or metal enclosure in which electrons move through the vacuum or gas from one metal electrode to another. The vacuum tube is often used to amplify weak currents or act as a one-way valve (rectifier) for electric current. Before the 1947 invention of the transistor the electron tube was the basis of virtually all electronic devices. The simplest kind of electron tube is the diode, which was invented in 1904 by John A. Fleming.
A vacuum distillation is used when the boiling point of the compound or the solvent is too high in order to distill the compound or the solvent off without significant decomposition. is based on the fact that under vacuum the boiling point of the materials is lower than at normal atmospheric pressure.