Definition

Noun: 1. A resistor inserted into a circuit to compensate for changes (as those arising from temperature fluctuations): A ballast resistor is an electrical component used to maintain a steady current in a circuit by automatically adjusting its resistance in response to changes, such as those caused by temperature variations.

Usage

A ballast resistor is used to stabilize electrical current. It is commonly placed in series with another component, like a lamp or a transistor, to prevent the current from increasing uncontrollably. As the current tries to rise (often due to the component heating up and its resistance dropping), the ballast resistor's own resistance increases, which counteracts the change and keeps the overall current stable.

Examples

• In a circuit:
• Describing function:
• Identifying a component:

Advanced Usage

• Electrical Stability: In advanced electronics, a ballast resistor is crucial for protecting sensitive components from current surges that can occur during startup or due to environmental factors.
• Negative Feedback: The ballast resistor operates on a principle of negative feedback, where its property changes to oppose any change in the circuit's operating condition.

Variants and Related Words

• Ballast (noun): In a broader electrical context, "ballast" can refer to any device (including inductors or electronic circuits) used to limit current. The "ballast resistor" is a specific type of ballast.
• Current-limiting resistor (noun): A general term for any resistor used primarily to restrict current flow, which is the primary function of a ballast resistor.
• Barretter (noun): A historical term for a specific type of ballast resistor, often a wire filament in a hydrogen-filled bulb, whose resistance increases with current.

Synonyms

• Stabilizing resistor
• Current-regulating resistor

Related Technical Terms

• Positive Temperature Coefficient (PTC): A property of materials where resistance increases with temperature. Many ballast resistors are made from PTC materials.
• Thermal Runaway: The unstable condition a ballast resistor is designed to prevent, where increasing current causes more heat, which lowers resistance, allowing even more current to flow in a destructive cycle.

Noun

1. a resistor inserted into a circuit to compensate for changes (as those arising from temperature fluctuations)