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Transistorized Ignition: Why A Transistorized Ignition is Better?

Welcome to our transistorized ignition guide. You are probably asking yourself who needs a transistorized ignition when we can use breaker points. 

Well, we’ve got the answers below. This guide will cover the upsides of this type of system and elaborate on its working principle. 

And before we come to the details, here is the spoiler- A transistorized ignition system uses a transistor, as per its name. For more, let us delve into the details. 

Table of Contents

What Is a Transistorized Ignition System?

It is an ignition mode that utilizes a transistor instead of the mechanical devices common in other systems. Its cardinal difference from the conventional ignition system featuring breaker points is that it lacks moving parts. 

Notably, a transistorized ignition system is more efficient. So how does the transistor help achieve this? The electronic component is key in the control of high current-carrying circuits. 

It ensures a low current on the base circuit and controls the high current at the collector. 

Hence the device is critical in improving the performance of the contact breaker. This setup is the genesis of the name- transistorized ignition system. 

Also noteworthy is that this layout aims to introduce electronic switches instead of manual ones. These are better than the conventional breaker points in old-school automotive ignition systems. 

Why Are Transistors Used Instead of Breaker Points?

A Car's Starter motor. 

A Car’s Starter motor. 

A breaker point is essential for electromagnetic induction resulting from breaking the ignition coil’s primary coil current. Nonetheless, everything about breaker points is mechanical as it involves widening the breaker point gap, usually via a cam. 

Its main downsides include: 

  • The system has reduced efficiency primarily because of the moving parts that are subject to rubbing against each other. 
  • Also, breaker point sparking is highly likely, which can lower the coil’s induction power.

So the electronic switch with a transistor aims to eliminate these limitations and have a more seamless system. 

Parts and Construction

A Spark Plug. 

A Spark Plug. 

Below are some of the major components of this system: 

Circuit Layout

The transistor’s emitter connects to the ignition coil via a ballast resistor while the battery connects to the collector. Here’s a schematic/ circuit diagram of the setup. 

A Transistorized ignition circuit diagram.

A Transistorized ignition circuit diagram.

Working Principle

Auto mechanic uninstalling an Ignition Coil. 

Auto mechanic uninstalling an Ignition Coil. 

The operation of this electronic switch is pretty straightforward. 

When you turn on the engine, the automobile’s crankshaft activates the pickup coil, which creates a low-voltage current. Next, this prompts the activation of the transistor base foot facilitating the collector connection to the emitter. 

Now, there will be a current transfer from the system’s battery to both sides of the ignition coil. Next, the zig-zag electric current from the pick-up coil transfers to the transistor’s base terminal. 

Induction occurs when the transistor base foot briefly doesn’t receive a current. 

Now let’s illustrate what occurs when we break and open the contact breaker. 

Closed Contact Breaker

Now, there’s a minute current flow in the transistor’s base. It causes a flow of current in the collector and emitter circuit and the ignition coil’s primary windings. The result is a magnetic field on the ignition coil. 

Open Contact Breaker

It results in the termination of the base circuit current flow rendering the transistor non-conductive. In turn, this leads to a reduction of the coil’s magnetic field and primary current. 

But there’s a significant high voltage generation in the secondary circuit. Next, the distributor’s rotor sends the high voltage to the spark plugs, creating a spark. Finally, this spark ignites the air and fuel mixture. 

Advantages and Disadvantages of a Transistorized Ignition System

An Auto mechanic testing and checking ignition coils.

An Auto mechanic testing and checking ignition coils.

Upsides of the Transistorized Ignition Control System

  • The vehicle ignition system results in an extensive lifespan of contact breaker points. Again it guarantees excellent ignition system performance. 
  • Also, the ignition voltages are remarkably high, and there is lengthier and more frequent sparking than in conventional systems. The duration of sparks is critical as it affects the overall efficiency of the ignition system. 
  • You don’t need extensive maintenance practices for the system; finally, it guarantees precise timing control. 

Downsides of the Transistorized Ignition Control System

  • Sidetracking is common with this vehicle ignition system. Also, it doesn’t 100% eliminate the mechanical points. 


At the core of a Transistorized Ignition Control System is efficiency. It is virtually impossible to realize with the typical breaker points setup. 

Hence, as we have highlighted, this system is better thanks to its relatively low number of moving parts. 

It also barely breaks down, and this is a critical advantage as it saves you on frequent ignition system repairs. 

Finally, its setup is pretty simple, as illustrated in the circuit diagram. Hence, it’s outrightly easy to perform diagnostic measures on the system. 

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