Blog  /  Voltage Stabilizer Car: A Complete Beginner’s Guide

Voltage Stabilizer Car: A Complete Beginner’s Guide

Are you looking for the perfect circuit to control the voltage fluctuations in your car and other equipment? If yes, what you're looking for is a voltage stabilizer.

Voltage stabilizers can constantly keep up with fluctuations, so your equipment or vehicle doesn't encounter problems when you change speeds or press the brake.

However, designing a voltage stabilizer can be tricky, and there are many things to consider if you want to get it right. But that's why we're here.

In this article, you'll learn about voltage stabilizers and how to make one for your car.  

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What is a Voltage Stabilizer?

Voltage stabilizers are electrical devices capable of delivering a stable voltage to the load connected to its output terminals. Plus, the voltage it provides remains constant no matter what changes occur to its input voltages.  

Voltage stabilizers protect vehicles and electrical components from voltage surges, including over-and under-voltage.

Most people use voltage stabilizers to protect expensive electrical equipment from dangerous voltage fluctuations. Such kit includes vehicles, medical equipment, air conditioners, and many more.

Also, voltage stabilizers are like filters regulating fluctuating voltages before reaching loads damage from voltage variations. Plus, the voltage stabilizer keeps its voltage supply anywhere between 220v and 230v if you're using a single-phase supply. For three-phase supplies, it stays between 380v and 400v.

Interestingly, you can find various single -and three-phase automatic stabilizers in the market. Plus, you can always find the right one needed for your application. Additionally, you can find two types of three-phase stabilizers, including unbalanced load models and balanced load models.  

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Why Your Car Needs a Voltage Stabilizer

A car's battery is a voltage and current source and sometimes acts as a voltage stabilizer. So we can have low electricity requirements and high electricity requirements. But that's not all. It would be best if you had an alternator to have your car generate electricity; there might be an overflow of electricity, depending on what the vehicle requires.  

If a car doesn't require much electricity, it will only take the amount of power it needs from the alternator. Interestingly, this leads to a supply of excessive current, leading to a surge. But the battery stops this by using the excess electricity as a charging source. In other words, the alternator transfers the extra current to the battery to charge up. Here's an example of a battery acting as a voltage stabilizer.

Alternatively, if the car requires large amounts of electricity, it's usually more than the alternator can handle. So, to keep up with the demand, the vehicle will also draw current from the battery.

In such cases, the battery won't easily switch from charge to discharge mode quickly enough to handle voltage fluctuations. So, you end up with low performance and possibly a damaged car.

However, this is where the voltage stabilizer steps in. It would help you control the voltage supply and protect your car from high or low voltage fluctuations. There are other benefits to using a voltage regulator, such as decreased fuel consumption and higher torque.  

How Does it Work?

A voltage stabilizer corrects over and under voltage by using two operations: the buck and boost functions.

You can perform these operations either manually or automatically. For manual processes, you'll be using switches. For automatic functions, you'll use electronic circuitry.

Here's the best part. When your vehicle or equipment suffers from under-voltage conditions, the boost operations will kick in and increase the voltage to the required level.

On the other hand, if it's an overvoltage condition, the buck operation activates to reduce the voltage to an acceptable level.

Thus, the entire concept of stabilization revolves around adding and subtracting. The voltage stabilizer will either add or subtract voltage from the mains voltage.

Such a task requires a transformer connected in multiple configurations with switching relays. While some voltage stabilizers tap on windings transformers to keep with different voltage conditions, others use autotransformers for various corrections.  

Voltage Stabilizer Circuit

Circuit Diagram

Circuit Diagram


Here, we have an easy voltage stabilizer circuit that you can complete in a few easy steps. Also, you'll need the following components if you want to build this circuit.

  • Three by 3 inches General purpose board
  • 1N4007 diode (2) (D1, D2)
  • 10k linear preset (P1)
  • 3v/400 mW Zener diode (Z1)
  • 220uF/25v capacitor



  • Resistor (R1)
  • BC547 transistor (T1)
  • Transformer (T1) : 12 – 0 – 12 V / 5 amps
  • Transformer (T2): 0 – 12 volts / 500 mA
  • Relay (RL1): 12 V / DPDT mini

Circuit Description

Looking at the circuit diagram, you can see that the transistor (T1) serves as the primary active component of the circuit.

D1 and C1 of the circuit serve as a rectifier. Plus, it filters respectively for the voltage coming from the smaller transformer.

This process allows the transformer to generate sufficient power required by the circuit consisting of a transistor, preset, DPDT relay, and Zener diode.

The voltage also serves as the sensing voltage because it will vary proportionately, depending on the voltage variations applied at the input.

For instance, let's say the standard operating DC voltage is 15v. If you increase or decrease the input AC mains voltage by 28v, you'll either increase the DC voltage to 17v or reduce it to 13v.

Additionally, you can program the P1 in such a way that allows the transistor to operate. For example, conduct the relay when the AC input mains deviates from the standard voltage.

Though the present design is essential and might not deliver precise stabilization, it can keep the output voltage between 200v to 250v or 100v to 125v.  

How to Build

As we mentioned earlier, you can quickly build this circuit in a few easy steps.

Fiyou'llou'll need to place your transistor on the general-purpose board and then solder and trim its leads.

Next, assemble and solder the other components listed above to the board.

Then, follow the circuit schematic to interlink all the soldered components and former's secondary wires to the relay contacts.  

How to Test the Voltage Stabilizer Car

Once you have your completed circuit, here's how you can test it.

First, you'll need a 0v-12v universal DC variable power supply for this test.

You can start the test by connecting supply terminals for your circuit to a power supply. But, first, ensure the power supply voltage stays in the 12v top position.

Next, steadily adjust the preset until the relay activates. So when you decrease the power supply by 1v, it should deactivate you'll have a complete and working voltage stabilizer circuit.  

Wrapping Up

Installing voltage stabilizer circuits in your vehicles and equipment could save them from dangerous voltage surges and fluctuations.

It would also protect your equipment's performance and make them optimal. You can buy a voltage stabilizer from the market or build one to fit your needs and tastes.

If you have further questions on what type of voltage stabilizer to don't build, don't hesitate to contact us.    

Special Offer: $1 for 5 PCB Assemblies!

One requirement only: Order must be placed using a company account.
Please email [email protected] for details.
Special Offer: $1 for 5 PCB Assemblies!