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.
Use of Vacuum Tube Diodes Gradually p-n junction semiconductor has come in the market and vacuum tubes got replaced by them. The most basic structure of vacuum tube is vacuum diode. Still today somewhere vacuum tubes are being used widely. These fields for application of the vacuum tubes are in Atomic Clocks; Audio Systems; Car Dashboards
The vacuum tube (known as a 'valve' in the UK) is an interesting component that made many important technologies possible and it is still used in many things. There are many kinds of vacuum tubes for different jobs. Most types of vacuum tubes have been replaced by semiconductor devices, however vacuum tubes will occupy an important role in the future in the field of nanotechnology. All 'tubes' basically consist of an anode and cathode in a gas or vacuum environment.