Vacuum tube battery

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A generic triode vacuum tube circuit showing "A", "B" and "C" batteries Triode Circuit.svg
A generic triode vacuum tube circuit showing "A", "B" and "C" batteries

In the early days of electronics, devices that used vacuum tubes (called valves in British contexts), such as radios, were powered by batteries. Each battery had a different designation depending on which tube element it was associated with.

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Initially, the only such device was a diode with only a filament (cathode) and a plate (anode). Following the direction of electron flow, these electrodes are identified as "A" and "B", respectively and thus the associated batteries are referred to as the "A" and "B" batteries respectively. Later, when the control grid element was added to create the triode tube, it was logically assigned the letter "C" and supplied from a "C" battery. Subsequent addition of further internal elements to improve the performance of the triode did not require an extension to this series of batteries these elements are either resistively-biased from the existing batteries or connected to ground or to the cathode.

This nomenclature is used primarily within North America. Different battery names are used elsewhere in the English-speaking world.

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Eveready No. 742
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1+1/2-volt "A" battery with Fahnestock clip terminals A battery (Eveready -742).jpg
Eveready No.7421+12-volt "A" battery with Fahnestock clip terminals

The "A" battery is used to provide power to the filament. It is sometimes colloquially referred to as a "wet battery". (A dry cell could be used for the purpose, but the ampere-hour capacity of dry cells was too low at the time to be of practical use in this service.) The term comes from the days of valve (tube) radios when it was common practice to use a dry battery for the plate (anode) voltage and a rechargeable lead-acid "wet" battery for the filament voltage. (The filaments in vacuum tubes consume much more current than the anodes, and so the "A" battery drains much more rapidly than the "B" battery; therefore, using a rechargeable "A" battery in this role reduces the need for battery replacement. In contrast, a non-rechargeable "B" battery needs to be replaced relatively infrequently.) "A" batteries were initially 2 volts, being lead-acid accumulators, but with the introduction of all-dry-battery radios, 1.4 volts became more common. Other voltages can be encountered. For example, 7.5-volt batteries are sometimes used to power a series-connected set of 1.4-volt valves (tubes). In Britain and some other countries, the "A" battery is known as the "LT" (low tension) battery if dry, and simply the "accumulator" if wet. Later, it became common practice to repurpose standard dry cells or multi-dry cell batteries as "A" batteries. A modified No. 6 cell was often used, later packs of multiple F-cells were used. In the early days of transistor radio, a single G-cell would often be used as the A battery.

Eveready No. 762-S 45-volt "B" battery with
22+1/2-volt tap screw terminals B battery (Eveready -762-S).jpg
Eveready No.762-S 45-volt "B" battery with 22+12-volt tap screw terminals

The "B" battery is used to provide the plate voltage. It is sometimes colloquially referred to as a "dry battery" (although there is no reason why a "wet" battery of suitable voltage could not be utilised for the purpose). The filament is primarily a heat source and therefore the "A" battery supplies significant current and rapidly discharges. The "B" battery experiences comparatively little current draw and retains its stored capacity far longer than an "A" battery. Early "B" batteries used with bright emitter tubes were 120 volts, but these quickly became obsolete as they were replaced with examples having voltages of typically 45 volts, 67+12 volts, or 90 volts as more efficient tubes became available. Some examples have taps every 22+12 volts. The last B batteries sold were 22 1/2 volts and similar in size to a PP3 9-volt battery. Even when the plate voltage rail is fed by a power supply rather than a battery, it is generally referred to as the "B+" line in American schematics. Because plate voltages can be as high as 300  V DC, multiple "B" batteries may be connected together in series to additively provide the required operating voltages. The much higher available voltage of "B" batteries means that they must be handled more carefully than other battery types due to their ability to shock or burn the person handling them. In Britain and in some other countries, the "B" battery is known as the "HT" (high tension) battery.

Eveready No. 761
4+1/2-volt "C" battery with
1+1/2- and 3-volt tap screw terminals C battery (Eveready -761).jpg
Eveready No.7614+12-volt "C" battery with 1+12- and 3-volt tap screw terminals

The "C" battery is used to provide bias to the control grid. Until the early 1930s this was common practice in valve (tube) radio sets but was largely superseded by grid leak resistors or voltage divider biasing. Because the tube grids draw no current, the "C" battery provides the bias voltage with no current draw. The battery's life in the radio is essentially its shelf life. In more recent times, they were popular in schools and colleges as a convenient variable voltage source in science classes. EverReady was still manufacturing them in the 1970s. The most popular battery is the 9-volt type with taps every 1+12 volts that accept banana plugs. [1] A rare form of "C" battery is the bias cell, a button-size miniature battery designed to deliver a constant voltage with no current drain. These were briefly popular between 1936 and 1945 as the bias cell was less costly than a resistor/capacitor bias network. [2] In Britain and in some other countries, the "C" battery is known as the "GB" (grid bias) battery.

See also

Related Research Articles

<span class="mw-page-title-main">Triode</span> Single-grid amplifying vacuum tube having three active electrodes

A triode is an electronic amplifying vacuum tube consisting of three electrodes inside an evacuated glass envelope: a heated filament or cathode, a grid, and a plate (anode). Developed from Lee De Forest's 1906 Audion, a partial vacuum tube that added a grid electrode to the thermionic diode, the triode was the first practical electronic amplifier and the ancestor of other types of vacuum tubes such as the tetrode and pentode. Its invention helped make amplified radio technology and long-distance telephony possible. Triodes were widely used in consumer electronics devices such as radios and televisions until the 1970s, when transistors replaced them. Today, their main remaining use is in high-power RF amplifiers in radio transmitters and industrial RF heating devices. In recent years there has been a resurgence in demand for low power triodes due to renewed interest in tube-type audio systems by audiophiles who prefer the sound of tube-based electronics.

<span class="mw-page-title-main">Vacuum tube</span> Device that controls current between electrodes

A vacuum tube, electron tube, valve, or tube, is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.

A tetrode is a vacuum tube having four active electrodes. The four electrodes in order from the centre are: a thermionic cathode, first and second grids, and a plate. There are several varieties of tetrodes, the most common being the screen-grid tube and the beam tetrode. In screen-grid tubes and beam tetrodes, the first grid is the control grid and the second grid is the screen grid. In other tetrodes one of the grids is a control grid, while the other may have a variety of functions.

<span class="mw-page-title-main">Thyratron</span> Gas-filled tube, electrical switch, rectifier

A thyratron is a type of gas-filled tube used as a high-power electrical switch and controlled rectifier. Thyratrons can handle much greater currents than similar hard-vacuum tubes. Electron multiplication occurs when the gas becomes ionized, producing a phenomenon known as a Townsend discharge. Gases used include mercury vapor, xenon, neon, and hydrogen. Unlike a vacuum tube (valve), a thyratron cannot be used to amplify signals linearly.

<span class="mw-page-title-main">Pentagrid converter</span> Frequency mixer of a superhet radio

The pentagrid converter is a type of radio receiving valve with five grids used as the frequency mixer stage of a superheterodyne radio receiver.

<span class="mw-page-title-main">Control grid</span> Electrode used to control electron flow within a vacuum tube

The control grid is an electrode used in amplifying thermionic valves such as the triode, tetrode and pentode, used to control the flow of electrons from the cathode to the anode (plate) electrode. The control grid usually consists of a cylindrical screen or helix of fine wire surrounding the cathode, and is surrounded in turn by the anode. The control grid was invented by Lee De Forest, who in 1906 added a grid to the Fleming valve to create the first amplifying vacuum tube, the Audion (triode).

<span class="mw-page-title-main">All American Five</span> American radio with 5 vacuum tubes

The term All American Five is a colloquial name for mass-produced, superheterodyne radio receivers that used five vacuum tubes in their design. These radio sets were designed to receive amplitude modulation (AM) broadcasts in the medium wave band, and were manufactured in the United States from the mid-1930s until the early 1960s. By eliminating a power transformer, cost of the units was kept low; the same principle was later applied to television receivers. Variations in the design for lower cost, shortwave bands, better performance or special power supplies existed, although many sets used an identical set of vacuum tubes.

<span class="mw-page-title-main">Pentode</span> Vacuum tube with five electrodes

A pentode is an electronic device having five electrodes. The term most commonly applies to a three-grid amplifying vacuum tube or thermionic valve that was invented by Gilles Holst and Bernhard D.H. Tellegen in 1926. The pentode was developed from the screen-grid tube or shield-grid tube by the addition of a grid between the screen grid and the plate. The screen-grid tube was limited in performance as an amplifier due to secondary emission of electrons from the plate. The additional grid is called the suppressor grid. The suppressor grid is usually operated at or near the potential of the cathode and prevents secondary emission electrons from the plate from reaching the screen grid. The addition of the suppressor grid permits much greater output signal amplitude to be obtained from the plate of the pentode in amplifier operation than from the plate of the screen-grid tube at the same plate supply voltage. Pentodes were widely manufactured and used in electronic equipment until the 1960s to 1970s, during which time transistors replaced tubes in new designs. During the first quarter of the 21st century, a few pentode tubes have been in production for high power radio frequency applications, musical instrument amplifiers, home audio and niche markets.

<span class="mw-page-title-main">Nine-volt battery</span> Form of small battery

The nine-volt battery, or 9-volt battery, is an electric battery that supplies a nominal voltage of 9 volts. Actual voltage measures 7.2 to 9.6 volts, depending on battery chemistry. Batteries of various sizes and capacities are manufactured; a very common size is known as PP3, introduced for early transistor radios. The PP3 has a rectangular prism shape with rounded edges and two polarized snap connectors on the top. This type is commonly used for many applications including household uses such as smoke and gas detectors, clocks, and toys.

In Europe, the principal method of numbering vacuum tubes was the nomenclature used by the Philips company and its subsidiaries Mullard in the UK, Valvo(deit) in Germany, Radiotechnique (Miniwatt-Dario brand) in France, and Amperex in the United States, from 1934 on. Adhering manufacturers include AEG (de), CdL (1921, French Mazda brand), CIFTE (fr, Mazda-Belvu brand), EdiSwan (British Mazda brand), Lorenz (de), MBLE(frnl), RCA (us), RFT(desv) (de), Siemens (de), Telefunken (de), Tesla (cz), Toshiba (ja), Tungsram (hu), and Unitra. This system allocated meaningful codes to tubes based on their function and became the starting point for the Pro Electron naming scheme for active devices.

<span class="mw-page-title-main">GU-50</span>

The GU-50 is a power pentode vacuum tube intended for 50 watt operation as a linear RF amplifier on frequencies up to 120 MHz. It is, in fact, a Soviet-produced copy of the Telefunken LS-50 power pentode, possibly reverse-engineered from German (Wehrmacht) military radios captured during World War II, or based on documentation, machines and materials captured as a trophy. It is one of the more unusual types of tube because of its non-standard 8-pin base and a metal "cap" with a plastic "handle" on top of the envelope - which is meant to ease extracting the tube from its socket. One stock Russian-produced socket includes a rugged die-cast metal cage-like enclosure for the tube with spring-loaded locking lid.. Another stock Russian-produced socket is stamped of light aluminium sheet metal, without a lid on top.

<span class="mw-page-title-main">History of the battery</span> History of electricity source

Batteries provided the primary source of electricity before the development of electric generators and electrical grids around the end of the 19th century. Successive improvements in battery technology facilitated major electrical advances, from early scientific studies to the rise of telegraphs and telephones, eventually leading to portable computers, mobile phones, electric cars, and many other electrical devices.

<span class="mw-page-title-main">Valve RF amplifier</span> Device for electrically amplifying the power of an electrical radio frequency signal

A valve RF amplifier or tube amplifier (U.S.) is a device for electrically amplifying the power of an electrical radio frequency signal.

<span class="mw-page-title-main">Magic eye tube</span> Visual indicator of the amplitude of an electronic signal

A magic eye tube or tuning indicator, in technical literature called an electron-ray indicator tube, is a vacuum tube which gives a visual indication of the amplitude of an electronic signal, such as an audio output, radio-frequency signal strength, or other functions. The magic eye is a specific type of such a tube with a circular display similar to the EM34 illustrated. Its first broad application was as a tuning indicator in radio receivers, to give an indication of the relative strength of the received radio signal, to show when a radio station was properly tuned in.

In the years 1942-1944, the Radio Manufacturers Association used a descriptive nomenclature system for industrial, transmitting, and special-purpose vacuum tubes. The numbering scheme was distinct from both the numbering schemes used for standard receiving tubes, and the existing transmitting tube numbering systems used previously, such as the "800 series" numbers originated by RCA and adopted by many others.

<span class="mw-page-title-main">Electric battery</span> Power source with electrochemical cells

An electric battery is a source of electric power consisting of one or more electrochemical cells with external connections for powering electrical devices. When a battery is supplying power, its positive terminal is the cathode and its negative terminal is the anode. The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal. When a battery is connected to an external electric load, a redox reaction converts high-energy reactants to lower-energy products, and the free-energy difference is delivered to the external circuit as electrical energy. Historically the term "battery" specifically referred to a device composed of multiple cells; however, the usage has evolved to include devices composed of a single cell.

<span class="mw-page-title-main">955 acorn triode</span> Thermionic valve for VHF operation

The type 955 triode "acorn tube" is a small triode thermionic valve designed primarily to operate at high frequency. Although data books specify an upper limit of 400–600 MHz, some circuits may obtain gain up to about 900 MHz. Interelectrode capacitances and Miller capacitances are minimized by the small dimensions of the device and the widely separated pins. The connecting pins are placed around the periphery of the bulb and project radially outward: this maintains short internal leads with low inductance, an important property allowing operation at high frequency. The pins fit a special socket fabricated as a ceramic ring in which the valve itself occupies the central space. The 955 was developed by RCA and was commercially available in 1935.

In vacuum tube technology, HT or high tension describes the main power supply to the circuit, which produces the current between anode and cathode. It is also known as the plate supply or voltage, B battery supply, or simply labeled →B on circuit diagrams, from the days of battery powered circuitry.

<span class="mw-page-title-main">TM (triode)</span>

The TM was a triode vacuum tube for amplification and demodulation of radio signals, manufactured in France from November 1915 to around 1935. The TM, developed for the French Army, became the standard small-signal radio tube of the Allies of World War I, and the first truly mass-produced vacuum tube. Wartime production in France is estimated at no less than 1.1 million units. Copies and derivatives of the TM were mass-produced in the United Kingdom as Type R, in the Netherlands as Type E, in the United States and in Soviet Russia as P-5 and П7.

References

  1. A relatively modern grid bias battery manufactured for school science use. Although claimed as a 1940 battery, the design of the logo the battery colour and the battery type puts this as post 1975, many decades after they ceased to be used for grid biasing. Prior to 1975 they were designated as type 'Winner' and were dark blue in colour with a more complex logo.
  2. "The Mallory Bias Cell" (PDF). Retrieved August 2, 2020.