Batteryless radio

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Radio receivers were originally operated by battery. The term batteryless radio was initially used for the radio receivers which could be used directly by AC mains supply (mains radio).

It was invented on April 8, 1925 in Canada by Edward S. Rogers, Sr., who made world history when he and his two chief engineers built the world’s first AC mains powered radio. The unit operated with 5 Rogers AC vacuum tubes and the Rogers Battery-Eliminator Power Unit (power supply). This unit later becomes marketed for $120 ^[1] as "Type 120". He established the Toronto station CFRB (an abbreviation of Canada's First Roger's Batteryless) to promote sales of the product. Batteryless Radio were not introduced in the United States until May, 1926 and then in Europe in 1927. ^[2]

Crystal radio receivers are a very simple kind of batteryless radio receiver. They do not need a battery or power source, except for the power that they receive from radio waves using their long outdoor wire antenna.

Thermoelectricity was widely used in the remote parts of the Soviet Union from the 1920s to power radios. The equipment comprised some bi-metal rods (thermocouples), one end of which could be inserted into the fireplace to get hot with the other end left out in the cold.

After Second World War, kerosene radios were made in Moscow for use in rural areas. These all-wave radios were powered by the kerosene lamp hanging above it. A group of thermocouples was heated internally to 570 degrees Fahrenheit (300 °C) by the flame. Fins cool the outside to about 90 degrees Fahrenheit (32 °C). The temperature differential generates enough current to operate the low-drain receiver.^[3]

Foot operated radio or pedal radio were once used in Australia. Another way of achieving the same function is clockwork radio, hand crank radio and solar radio. ^[4]

See also

• Batteryless switch
• Invention of radio
• Thermogenerator
• Pyroelectric effect - the creation of an electric field in a crystal after uniform heating
• Radio receiver

References