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
Jul 24, 2014. J.J. Thomson used a cathode ray tube to discover the electron. Cathode ray tubes are vacuum tubes that contain two electrodes - one on each side. One of the electrodes (the cathode) fires electrons at the other (the anode) when voltage is added to the system. When Thomson fired up the tube, he saw a beam of light between the two electrodes. To figure out what they were, he applied a magnetic field and found out that the beam moved toward a positive charge and away from a negative charge.