Definition

Noun: 1. A type of battery used to supply power for heating the filament (cathode) in a vacuum tube: This is a specific, technical term from early electronics. An "A battery" provides the low-voltage, high-current power needed to make the filament in a vacuum tube (or valve) glow hot, which is essential for the tube to function by emitting electrons.

Usage Notes

• This term is now largely historical and technical. It is primarily encountered in the context of antique radios, early electronics, or historical technical manuals.
• It is part of an old naming convention for power supplies in vacuum tube circuits:
  • A battery: Heats the filament (provides "A" power).
  • B battery: Provides the high voltage for the plate/anode (provides "B" power).
  • C battery: Provides bias voltage for the grid (provides "C" power).
• In modern language, the term "battery" alone almost never refers to this specific type unless the context is explicitly about vintage tube-based equipment.

Examples of Usage

• Noun:
  • The old radio required a fresh A battery to power the tube filaments.
  • In the circuit diagram, the A battery is connected directly to the filament pins of the vacuum tube.
  • Restorers of antique electronics often need to find a suitable replacement for the original A battery.

Advanced Usage

• The term can be used metaphorically or humorously to refer to a fundamental, low-level power source that enables a more complex system to operate, though this is very rare.
  • "Coffee is my A battery; without it, none of my mental circuits function."

Variants and Related Words

• B battery (n): The battery that supplies the high-voltage DC potential to the plate (anode) of a vacuum tube.
• C battery (n): The battery that supplies the bias voltage to the control grid of a vacuum tube.
• Filament battery (n): A synonym for "A battery," describing its function more directly.
• Heater supply (n): A modern technical term for the power source that heats the cathode in a vacuum tube or a cathode-ray tube (CRT).

Synonyms

• Filament battery
• Heater supply (in modern terminology for similar function)
• Low-voltage power supply (descriptive, not a direct synonym)

Antonyms

• B battery: While not a true opposite, it serves the complementary high-voltage function in the same system.

Noun

1. the battery used to heat the filaments of a vacuum tube