Thermionic valves announced the start of the electronics age at the beginning of the 20th century. The first experiments with incandescent bulbs showed that a hot filament emitted electrons. This led to the development of thermionic diodes and other thermionic valves. These have the capability to convert alternating current into direct current, or to amplify changes in the current that is flowing. At that time they were used predominantly in broadcasting technology and in valve receivers, the predecessors of the transistor radio. Nowadays they are used only as amplifiers in amateur radio sets and in the field of music, for instance with guitars, in order to product the typical distorted sound. Cathode ray tubes are special electron tubes which create a concentrated beam of electrons. These can be directed using magnetic or electrical fields so that a visible picture is created. TV sets are amongst the devices that use these image tubes. The range from Bürklin Elektronik contains an unusually wide selection of these tubes; those who like to work on older TV sets will find it particularly useful. If nevertheless you cannot find the component you want, please do not hesitate to contact us.