Car radios

Radio receivers for automobiles were manufactured since the 1930s. The car radio of that time had a shape of a large metal box placed usually in the engine compartment. Only a control panel with a speaker was placed in the cab. The control panel was connected to the radio with bowden lines. Car radios were made mainly in the USA and these were also imported to Czechoslovakia. Regardless of the country of origin, a car radio was a luxury item for the rich, as was the car itself. After the war, tube car radios were manufactured here until 1960. A tube radio requires a small voltage for the heaters that could be taken directly from the car battery, but also a supply of approx. 250 V for the anodes. The only solution of the time was to use a rotary or vibration converter. The vibration converter composed of an electromagnet and a contact that would switch off the current of the magnet after its core moved. This caused the contact to vibrate and this was used as a source of alternating current that could be transformed to a higher voltage. A rotary converter would use an electric motor and a generator on the same shaft and was used in bus radios. Both of these systems were quite clumsy, unreliable and required good maintenance, so transistor radios were built as soon as possible. These were imported at first, domestic production started in 1972.