Radio

Radio

Radio is the transmission of signals through free space by modulation of electromagnetic waves with frequencies below those of visible light. Electromagnetic radiation travels by means of oscillating electromagnetic fields that pass through the air and the vacuum of space...

 receivers were originally operated by battery

Battery (electricity)

An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...

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

The line-operated vacuum tube receiver was invented in 1925 by Edward S. Rogers, Sr.

Edward S. Rogers, Sr.

Edward Samuel "Ted" Rogers is regarded as the founder of Rogers Communications although it was established in 1967, almost three decades after his death.-Life and career:...

. The unit operated with 5 Rogers AC vacuum tube

Vacuum tube

In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

s and the Rogers Battery-Eliminator Power Unit (power supply). This unit was later marketed for $120 as "Type 120". He established the Toronto

Toronto

Toronto is the provincial capital of Ontario and the largest city in Canada. It is located in Southern Ontario on the northwestern shore of Lake Ontario. A relatively modern city, Toronto's history dates back to the late-18th century, when its land was first purchased by the British monarchy from...

 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

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 until May, 1926 and then into Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 in 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

Antenna (radio)

An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...

.

Thermoelectricity was widely used in the remote parts of the Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

 from the 1920s to power radios. The equipment comprised some bi-metal rods (thermocouple

Thermocouple

A thermocouple is a device consisting of two different conductors that produce a voltage proportional to a temperature difference between either end of the pair of conductors. Thermocouples are a widely used type of temperature sensor for measurement and control and can also be used to convert a...

s), 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

Kerosene

Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin or paraffin oil in the United Kingdom, Hong Kong, Ireland and South Africa, is a combustible hydrocarbon liquid. The name is derived from Greek keros...

 radios were made in Moscow

Moscow

Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...

 for use in rural areas. These all-wave radios were powered by the kerosene lamp

Kerosene lamp

The kerosene lamp is a type of lighting device that uses kerosene as a fuel. This article refers to kerosene lamps that have a wick and a tall glass chimney. Kerosene lanterns that have a wick and a glass globe are related to kerosene lamps and are included here as well...

 hanging above them. A group of thermocouple

Thermocouple

A thermocouple is a device consisting of two different conductors that produce a voltage proportional to a temperature difference between either end of the pair of conductors. Thermocouples are a widely used type of temperature sensor for measurement and control and can also be used to convert a...

s was heated internally to 570 degrees Fahrenheit (300 °C) by the flame. Fins cooled the outside to about 90 degrees Fahrenheit (32 °C). The temperature differential generated enough current to operate the low-drain receiver.

Foot-operated radio or pedal radio

Pedal radio

The Pedal Radio is a radio powered by a pedal-driven generator. It was developed by Alfred Traeger in 1929 as a way of providing radio communications to remote homesteads in the Australian outback. There was no mains or generator power available at the time and batteries to provide the power...

 was once used in Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. Other ways of achieving the same function are clockwork radio

Clockwork radio

A windup radio or clockwork radio is a radio that is powered by human muscle power rather than batteries or the electrical grid. In the most common arrangement, an internal electrical generator is run by a mainspring, which is wound by a hand crank on the case. Turning the crank winds the spring...

, hand crank

Crank (mechanism)

A crank is an arm attached at right angles to a rotating shaft by which reciprocating motion is imparted to or received from the shaft. It is used to change circular into reciprocating motion, or reciprocating into circular motion. The arm may be a bent portion of the shaft, or a separate arm...

 radio and solar radio, especially for the Royal Flying Doctor Service and School of the Air

School of the Air

School of the Air is a generic term for correspondence schools catering for the primary and early secondary education of children in remote and outback Australia.-History:...

.

Carrier-powered radio

A carrier-powered radio is a batteryless radio which "leeches" its power from the incoming electromagnetic wave.
A simple circuit (very similar to a crystal set) rectifies the incoming signal and this DC current is then used to power a small transistor amplifier. Typically a strong local station is tuned in to provide power, leaving the listener free to listen to weaker and more distant stations.

See also

• Human-powered equipment

• Antique radio
  Antique radio
  An antique radio is a radio receiving set that is collectible because of its age and rarity. Although collectors may differ on the cutoff dates, most would use 50 years old, or the pre-World War II Era, for vacuum tube sets and the first five years of transistor sets.-Morse only sets:The first...
  
  
• Batteryless switch
• Invention of radio
  Invention Of Radio
  Within the history of radio, several people were involved in the invention of radio and there were many key inventions in what became the modern systems of wireless. Radio development began as "wireless telegraphy"...
  
  
• Pyroelectric effect - the creation of an electric field in a crystal after uniform heating
• Radio receiver
• Solar powered radio
  Solar powered radio
  A solar powered radio is a portable radio receiver powered by photovoltaic panels. It is primarily used in remote areas where access to power sources is limited.- History :...
  
  
• Thermogenerator
  Thermogenerator
  Thermoelectric generators are devices which convert heat directly into electrical energy, using a phenomenon called the "Seebeck effect" . Their typical efficiencies are around 5-10%...
  
  
• Windup radio

External links

• Museum of thermoelectric generators
• http://www.cam.net.uk/home/StKilda/electrolux.htmlHow kerosene refrigerator
  Refrigerator
  A refrigerator is a common household appliance that consists of a thermally insulated compartment and a heat pump that transfers heat from the inside of the fridge to its external environment so that the inside of the fridge is cooled to a temperature below the ambient temperature of the room...
  
  works]
• Image:Kerosene_radio.jpg
• International Thermoelectric Society
• Thermoelectric News