The earliest amplifying radios,
vacuum tube radios, used
batteries until the mid to late 1920s. The line-operated vacuum tube receiver was invented in 1925 by
Edward S. Rogers, Sr. The unit operated with five Rogers
AC vacuum tubes and the Rogers
Battery-Eliminator Power Unit (power supply). This unit was later marketed for $120 as "Type 120". He established the
Toronto station
CFRB (an abbreviation of ''Canada's First Rogers Batteryless'') to promote sales of the product. Batteryless radios were not introduced into the
United States until May 1926 and then into
Europe in 1927, and the industry did not widely produce batteryless radios until
RCA's AC tube in late 1927.
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. Sharp Electronics' first electrical product was a batteryless crystal radio introduced in 1925. It was Japan's first—and sold extremely well.
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 the
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 them. A group of
thermocouples was heated internally to by the flame. Fins cooled the outside to about . The temperature differential generated enough current to operate the low-drain receiver. Foot-operated radio or
pedal radio was once used in
Australia. Other ways of achieving the same function are
clockwork radio, hand
crank radio and
solar radio, especially for the
Royal Flying Doctor Service and
School of the Air. As part of an energy harvesting electronics system, some batteryless radios render electricity to storage by means of storage capacitors. In this batteryless type of radio, the storage capacitors cache the electricity as static on layers of dielectric instead of chemical changes, providing energy like batteries do but 'batteryless'. This can be quite effective. Storage capacitors recharge millions of times, they are relatively cheap, somewhat insensitive to temperature, and they never need replacing—which is why they are usually soldered on. As part of an energy autarkic or energy harvesting batteryless radio, therefore, storage capacitors are an integral part, storing electricity like battery does for lean energy periods, but in a 'batteryless' way which is more sustainable. About 15 billion batteries are consumed every year worldwide. == Carrier-powered radio ==