Which two circuits are found in an ignition system?

In an ignition system, the two circuits that are essential for its operation are the primary and secondary circuits. The primary circuit is responsible for delivering battery voltage to the ignition coil. When the ignition switch is turned on, current flows through the primary circuit, creating a magnetic field in the coil.

This magnetic field is crucial because when the primary circuit is interrupted (such as when the ignition points open in older systems or by a transistor in modern systems), it causes a rapid collapse of that magnetic field. This collapse induces a high voltage in the secondary circuit, which is connected to the spark plugs. The secondary circuit, therefore, is tasked with delivering this high voltage to the spark plugs, enabling them to create a spark that ignites the fuel-air mixture in the engine's cylinders.

Understanding these two circuits is fundamental to the operation of internal combustion engines and helps in diagnosing issues within the ignition system. The focus on primary and secondary circuits is essential because they directly influence the ignition timing and the overall efficiency of the engine's performance.