What component senses voltage fluctuations in both vibrating points and carbon pile regulators?

• A. Voltage coil
• B. Current coil
• C. Voltage regulator
• D. Magnetic core

Answer: (A)

Voltage sensing is what keeps the charging system stable, and the element that detects those voltage changes is the voltage coil. In vibrating-point regulators, the voltage coil responds to the battery/terminal voltage and creates a magnetic force that influences the regulator’s contacts, helping the system finely adjust the field current as voltage rises or falls so the output stays within the desired range. In carbon pile regulators, the same voltage-sensing action feeds back to the carbon pile circuit, raising or lowering resistance to maintain the correct terminal voltage. The current coil, by comparison, responds to current levels rather than voltage, so it isn’t the component that senses voltage fluctuations in these regulators.