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Transistor Ignition:

Transistor ignition is an advanced form of ignition system that utilizes transistors and specialized coils to improve the efficiency, reliability, and performance of the ignition process in internal combustion engines.


  1. Transistors: Transistors are semiconductor devices that act as switches to control the flow of current in the ignition system. They replace the traditional mechanical points found in conventional ignition systems.
  2. Coil: A special ignition coil designed to work with the transistorized ignition system. This coil is capable of generating the high-voltage sparks required to ignite the air-fuel mixture in the engine cylinders.
  3. Distributor: The conventional distributor is retained in the system, but its role is modified. Instead of directly controlling the primary current to the ignition coil, the distributor now triggers the transistor, which in turn switches the heavy primary current.


  1. Triggering Mechanism: As the distributor rotates, it sends a signal to the transistor when it’s time to initiate the ignition process for a specific cylinder. This signal triggers the transistor to switch on, allowing a controlled amount of current to flow through the ignition coil’s primary winding.
  2. Coil Operation: The current flowing through the ignition coil’s primary winding generates a magnetic field. When the transistor switches off, the magnetic field collapses rapidly, inducing a high-voltage pulse in the coil’s secondary winding. This pulse is then sent to the spark plugs to ignite the air-fuel mixture in the engine cylinders.


  1. Improved Efficiency: Transistors are much more efficient switches compared to mechanical points, especially at high engine speeds. They can switch on and off rapidly without burning, pitting, or altering the gap spacing, resulting in more reliable ignition timing and improved engine performance.
  2. Enhanced Reliability: Transistor ignition systems greatly increase the lifespan of ignition points since they pass only a minimal amount of current through the points. This leads to better contact conditions and significantly extended point life.
  3. Consistent Voltage Output: The voltage output of the ignition system is not greatly affected by the dwell time (the duration the points are closed), resulting in better performance at high engine speeds where dwell time is shorter.
  4. Improved Starting: The improved contact conditions and consistent voltage output of transistor ignition systems generally lead to better engine starting performance, especially in cold conditions or under heavy loads.

Transistor ignition systems represent a significant advancement over traditional mechanical ignition systems by utilizing transistors to control the ignition process. They offer improved efficiency, reliability, and performance, with benefits including extended point life, consistent voltage output, and enhanced starting capabilities. These systems have become commonplace in modern automotive engines, contributing to their overall reliability and performance.

See Related Term:

  • Breaker-triggered transistor ignition
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