What Is a Transformerless Power Supply?

What Is a Transformerless Power Supply?

Do you know what a transformerless power supply is? If not, don’t worry – you’re about to learn everything you need to know. In this article, we’ll provide an in-depth explanation of what transformerless power supplies are, how they work, and the benefits and drawbacks of using them. We’ll also give you our recommendations for the best transformerless power supplies on the market today. So whether you’re a business owner who’s looking to save on energy costs or a DIY enthusiast who wants to reduce the weight and size of their electrical projects, read on for all the information you need!

What is a Transformerless Power Supply

A transformerless power supply is an electrical device that converts the input voltage into a different output voltage (AC into DC).

Depending on the design, the output can be higher or lower than the input. It works by utilizing the voltage divider circuit to divide the input voltage into two unequal parts, which are then rectified and filtered to produce a DC output.

The transformerless power supply is more efficient than traditional transformers because it reduces the energy losses associated with heat dissipation and core saturation as well as reducing costs associated with bulky components like coils of wire. It also has a smaller form factor since it does not require a large transformer assembly.

What is a Transformerless Power Supply

Unlike a traditional transformer, which is usually made from two separate coils of wire, a transformerless power supply typically uses only one coil of wire for both the input and output. This makes them more efficient than transformers since there is less energy loss due to the reduced number of parts needed in the device. [1], [2], [3]

Types of Transformerless Power Supply

There are many types of transformerless power supplies available on the market today. In this section we will discuss the most common types and their advantages.

Resistive Transformerless Power Supply

A resistive transformerless power supply is a type of electrical power supply which uses an external resistance to provide the necessary amount of voltage.

It does not contain any form of transformer, and instead relies on the resistance that is provided by the load or other components in the circuit. This type of power supply can be very efficient and is often used where space or weight limitations exist, such as in mobile applications.

Resistive transformless power supplies drop the excessive energy as heat. This generates less output than a transformer-based power supply, but it is more efficient in terms of energy dissipation. As a result, these types of supplies are often used for applications where heat dissipation is important, such as computers and other electronic devices.

Capacitive Transformerless Power Supply

A Capacitive Transformerless Power Supply is a type of power supply that uses the capacitive and inductive reactance of components instead of transformers to step down voltage.

Here an X-rated capacitor is connected in series with the mains to drop the voltage and acts like a voltage dropping capacitor. This type of power supply has various advantages over traditional transformer-based supplies, including reduced size, weight and cost. [1]

Types of Transformerless Power Supply

Advantages of the Transformerless Power Supply

Now that you have an idea of what a transformerless power supply is, let’s take a deeper look at some of the advantages that it offers. And there are a plenty!


First things first, let’s talk about affordability. While traditional transformer-based power supplies are usually quite expensive, this is not the case with transformerless power supply. As their internal components are much simpler and require fewer parts, they usually come at a significantly lower cost. This can be especially helpful for those who need to fit a budget when buying new computer components.

They aren’t bulky at all

The other obvious advantage of a transformerless power supply is that it doesn’t take up too much space. Since all the components are integrated together, there’s no need for bulky external transformers or other types of enclosures, making them ideal for tight places where size and weight are a concern. This also makes it much easier to install and transport.

They can be used in low-powered electronic components

Another of the biggest advantages that transformerless power supplies have is their low power consumption. Because they don’t contain transformers, these supplies require less electricity to operate than other types of power supplies, making them ideal for use in low-powered electronic components. This makes them a great choice for powering sensitive components such as microcontrollers and logic boards within small devices or projects, where a larger supply could potentially damage the device. [1], [2], [3]

Advantages of the Transformerless Power Supply

Disadvantages of the Transformerless Power Supply

However, it’s not all good news. There are some downsides to using a transformerless power supply that you should be aware of. It’s important to be aware of these before making a decision about whether or not to use one in your application.

Risky to handle

One of the biggest disadvantages is that transformerless power supplies require much more skill and caution when it comes to handling. Without a transformer in place, the exposed electrical components can be very dangerous if they are touched or mishandled in any way. As such, they should only be handled by experienced professionals who understand all safety procedures and precautions.

This is because there’s no isolation from the input supply, meaning that an incorrect connection may cause a short circuit or other serious damage. Therefore, care should be taken to make sure the connections are secure and correct before powering up the supply.

They are unable to produce high current outputs

One of the biggest limitations of transformerless power supplies is their inability to produce high current outputs. Since they don’t have an external transformer, they are limited in terms of the amount of electricity they can provide. This means that if your application requires high amounts of current, you may need to look into a different type of supply.

They don’t isolate the circuit from dangerous AC mains potentials

Another downside of using a transformerless power supply is that it doesn’t provide the same level of protection as other types of supplies. Since there isn’t an external transformer, the circuit is not isolated from dangerous AC mains potentials, meaning that if something goes wrong, it can potentially cause serious harm to anyone in contact with the device. As such, extra care should be taken when designing and building circuits utilizing these supplies.

They aren’t fit for more complex systems

Unfortunately, transformerless power supplies are not a good choice for more complex systems. They are designed to work with low-powered components and don’t have the capacity to handle large amounts of current or voltage. So if you need to power something like an industrial machine or a heavy-duty piece of equipment, then you should look elsewhere for your power supply needs. [1], [2], [3]

Disadvantages of the Transformerless Power Supply

Applications of Transformerless Power Supply

As you can see, transformerless power supplies have their pros and cons. Despite the drawbacks however, they can still be a great choice for certain applications where size and weight are an issue but low power consumption is required. In this section, we will discuss some of the most popular applications for transformerless power supplies.

Telecommunication systems

One of the most popular applications for transformerless power supplies is telecommunication systems. This type of system typically requires a low-voltage, high-current power supply to operate its various components such as modems and routers. With their small size and weight, transformerless power supplies make an ideal choice for powering these types of systems. They are also more energy efficient than traditional transformers, meaning they can help keep energy costs down.

Mobile chargers

Mobile chargers are a great example of an application where transformerless power supplies can really shine. By using a transformerless power supply, mobile charger manufacturers are able to reduce the size and weight of their chargers significantly while still providing adequate current levels for charging your device. This makes them ideal for travelers who need something small and lightweight that they can easily slip into their bag or pocket.

LED bulbs

Transformerless power supplies are a great choice for powering LED bulbs. As we’ve already discussed, transformerless power supplies offer greater efficiency due to the lack of physical transformers and their associated losses. This makes them ideal for powering low wattage LED bulbs since they can provide light levels that would otherwise require much larger and heavier transformers. Additionally, transformerless power supplies give designers more flexibility when designing the circuits driving the LEDs, allowing them to customize the current-to-voltage ratios needed for different types of LED lights.

Applications of Transformerless Power Supply

Electronic toys

Transformerless power supplies are often used in electronic toys that require low power consumption. The small size of the units make them ideal for powering such toys, as they can fit easily into the toy’s housing with minimal space being taken up. This type of transformerless power supply is also very reliable and safe, making it suitable for use on devices intended for children.

Television receivers

TV receivers are the most common application for transformerless power supplies. Since their introduction in the late 1960s, these small, light-weight devices have become a staple of households all over the world. While early models had transformers, more modern versions have taken advantage of transformerless designs to reduce size and weight. These TVs typically use a buck converter as their main power supply, providing a steady voltage output with high efficiency.

Emergency lights

Transformerless power supplies are used in emergency lights. This is because they offer a great combination of efficiency and size, which makes them perfect for this application. For instance, transformerless LED drivers provide an efficient way to power LED lighting while also being small enough to fit into tight spaces or enclosures.

Digital communication systems

Digital communication systems often require a power supply that not only offers protection from voltage surges but is also lightweight and portable. Transformerless power supplies are ideal for this type of application as they provide reliable, continuous output power with excellent noise suppression capabilities. This makes them especially useful when powering devices such as routers, modems, switches and other digital communication equipment. [1], [2], [3]


What is transformerless power supply with explanation?

A transformerless power supply is a type of power supply circuit that eliminates the need for an electrical transformer by directly connecting the input AC voltage to the output DC voltage.

The goal of this design is to reduce size, cost and weight while improving efficiency.

These help reduce the size and weight of power supplies, making them ideal for applications where space is at a premium. To achieve this, they use components such as rectifiers, capacitors and integrated circuits to step down the input AC voltage to the desired DC output level.

Unlike traditional transformer-based power supplies, transformerless designs rely on active components (like integrated circuits) and passive components (such as capacitors). This means that they require regular maintenance in order to ensure optimal performance. Additionally, because these designs operate directly from mains voltage, high levels of electrical isolation can be difficult to achieve.

What is the disadvantage of transformerless power supply?

The main disadvantage of a transformerless power supply is its tendency to generate electrical noise. Since the transformerless power supply does not have any isolation between primary and secondary, it can cause electrical interference with other nearby electronic devices. This can lead to data loss or even system failure due to electromagnetic interference (EMI). Additionally, these types of supplies are usually not as efficient as those that use transformers. As the current passes through the components, some energy is lost in the form of heat which further decreases efficiency.

What is the advantage of the transformerless power supply?

The primary advantage of a transformerless power supply is its much smaller footprint compared to a traditional transformer-based design. Transformerless power supplies consist only of essential components, such as an output rectifier, filter capacitors, and a voltage regulator—all of which are housed in a single compact package. This eliminates the need for additional space to house bulky transformers, allowing for more efficient use of space in applications where size and weight matter most.

They are also pretty affordable, especially considering their smaller size and weight. Transformerless power supplies can be designed to meet the voltage requirements of a given application while still being relatively inexpensive.

Another huge advantage of transformerless power supplies is their high efficiency. Transformerless designs are able to convert AC mains input into DC output with greater efficiency than traditional transformer-based designs due to the reduced number of components involved in the conversion process. This improved efficiency results in lower overall cost of ownership for the power supply, as well as reduced energy consumption for applications that require constant operation.

What current is a transformerless power supply?

A transformerless power supply has a maximum current rating that is determined by the components used to construct it. Usually the current of a transformerless power supply will range from 0.2 Amps to 1 Amps, and the current is controlled with an external switch or by adjusting the components used in the design. The current that is provided by a transformerless power supply depends on how it has been designed; however, if safety issues are taken into consideration, then it’s usually best to limit the maximum current rating to no more than 10 Amps.

What are the different types of transformerless power supplies?

Transformerless power supplies come in several different varieties. The two most commonly used types are capacitive and resistive.

Capacitive transformerless power supplies are the most efficient because the heat dissipation and power loss are low. This type of power supply works by using a capacitor to store energy and then releasing it at the output. The capacitance value must be carefully tuned for each application so that the voltage is properly regulated.

Resistive transformerless power supplies are less efficient because they dissipate more heat and have higher power losses than their capacitive counterparts. The resistor is used across a voltage dropping resistor to drop the excess energy as heat.

What are the applications of transformerless power supply?

The applications of transformerless power supplies are varied and depend on the specific design, but some of the most common uses include providing power to low-power electronic systems like LED lighting, powering medical equipment such as nebulizers and pumps, powering automotive systems like electric windows and mirrors, and providing power for telecommunications equipment. In addition, they can be used in high-voltage or hazardous environments due to their intrinsic safety characteristics.

Transformerless power supplies are also becoming popular for use in green energy applications. By utilizing switch mode technology with an integrated rectifier/inverter components, these power supplies can provide a more efficient solution compared to traditional transformers which require large amounts of copper for winding the primary and secondary coils.

Useful Video: Capacitor Dropper Circuit | Transformerless Power Supply


Transformerless power supplies offer a variety of advantages, including cost savings, greater efficiency, and more compact size. However, they do come with certain risks that should be taken into consideration before using one. In particular, it is important to remember that these types of power supplies produce dangerous voltages and currents which can cause shocks or even fires if not properly designed and embedded within your system.

In this article, we have provided an overview of what a transformerless power supply is and its advantages and disadvantages. We have also covered important safety information to keep in mind before using one. As always, it is important to ensure that all safety measures are taken when dealing with high voltages and currents, so be sure to follow the manufacturer’s guidelines closely to ensure safe operation.

When used correctly and in accordance with best practices, transformerless power supplies provide great benefits in terms of cost savings, increased efficiency and space saving. As always though, when working with electricity it is important to remain vigilant and ensure the safety of yourself and those around you by following all instructions carefully and adhering to the relevant local building regulations. With these practices in mind, you can make the most of a transformerless power supply and enjoy its many advantages.

We hope that this guide has given you a better understanding of what is a transformerless power supply and how they work. If you are considering using one in your project, we recommend doing further research to ensure that it will be right for your particular needs and applications. Thank you for joining us on this journey into Transformerless Power Supplies!


  1. https://www.elprocus.com/what-is-transformerless-power-supply-its-working/
  2. https://www.homemade-circuits.com/cheap-yet-useful-transformerless-power/
  3. https://www.wellpcb.com/transformerless-power-supply.html