Definition of Adapter and its Function

Adapter is a circuit that is useful for converting a high AC voltage into a low DC voltage. The adapter is an alternative to DC voltage (such as batteries, batteries) because the use of AC voltage is longer and everyone can use it as long as there is electricity in the place.

Adapters are also widely used in tools as a power supply, such as amplifiers, radios, mini television sets and other electronic devices.

Electronic devices Adapters are very easy to manufacture because many of their components are sold in the market. (Source :

Understanding Adapter

In general, an adapter is an electronic circuit that functions to convert a high AC (alternating current) voltage into a lower DC (direct current) voltage.

As we know that the electric current we use at home, office, etc., is electric current from PLN (State Electricity Company) which is distributed in the form of alternating current or AC.
However, most of the electronic equipment that we use requires DC current with lower voltage for its operation. Therefore we need a device or electronic circuit that can change the current from AC to DC and provide a certain amount of voltage as needed. The circuit that functions to convert AC current into DC is called a DC power supply or adapter.

This series of adapters are installed or assembled directly on the electronic equipment and some are assembled separately. For adapters that are assembled separately, it is usually a universal adapter that has an output voltage that can be adjusted as needed, for example 3 Volts, 4.5 Volts, 6 Volts, 9 Volts, 12 Volts and so on. But besides that, there are also adapters that only provide a certain amount of voltage and are intended for certain electronic circuits, such as laptop adapters and monitor adapters.

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Adapter Function

As explained in the description above, the adapter is an electronic circuit that functions to convert AC current into DC current with a certain voltage as needed.

Adapter parts

In an adapter there are several parts or blocks, namely transformers (transformers), rectifiers (rectifiers) and filters

Transformer (Transformer)

Is a component that serves to decrease or increase the AC voltage as needed. In an adapter, the transformer used is a step-down transformer or a voltage-lowering transformer.

The transformer consists of 2 parts, namely the primary part and the secondary part, in each part there is a different number of turns of enamel wire. For a step-down transformer, the number of turns in the primary will be more than the number of secondary. The primary winding is the input of the transformer while the output is the secondary winding. Although the voltage has been lowered, the output of the transformer is still in the form of alternating current (AC current) which must be processed further.


In a series of adapters or power supplies, the voltage that has been lowered by the transformer, the current is still in the form of alternating current or AC. Because the current required by the electronic circuit is a DC current, it must be rectified first. The part that serves to rectify the AC current to DC on the adapter is called the rectifier (wave rectifier). Rectifier circuit usually consists of a diode component. In this rectifier circuit adapter circuit consists of 2 types, namely:

1. Half Wave Rectifier : using 1 rectifier diode

2. Full Wave Rectifier : using 2 or 4 rectifier diodes

using 4 diodes image source:

Filter (filter)

The filter is the part that serves to filter or even out the current signal coming out of the rectifier. This filter usually consists of a capacitor (Condenser) component of the type Electrolyte or ELCO (Electrolyte Capacitor).

Actually, with the transformer, rectifier and filter parts, the requirements of an adapter have been met, but sometimes the resulting voltage is usually unstable so another part is needed, which functions to stabilize the voltage and get an accurate voltage. This section is the regulator or voltage regulator.

Voltage Regulator (Voltage Regulator)

To produce a constant and stable DC voltage and current, a Voltage Regulator section is needed which functions to regulate the voltage so that the Output voltage is not affected by temperature, load current and also the input voltage from the Output Filter. Voltage Regulators generally consist of Zener Diodes, Transistors or ICs

In a sophisticated DC Power Supply, the Voltage Regulator is usually also equipped with Short Circuit Protection (short circuit protection), Current Limiting (Current Limiting) or Over Voltage Protection (overvoltage protection).

Adapter Type

In general, adapters are divided into two types, namely conventional adapters and adapters using a switching system or SMPS

1. Adapter or conventional power supply

In a conventional adapter or power supply, this AC voltage is first lowered through a step-down transformer and then rectified with a diode (rectifier) ​​and leveled with an electrolytic capacitor. The principle of this type of adapter still applies the mode of converting ac to dc voltage using a step-down transformer as the main component of voltage drop.

In this adapter, the amount of current generated depends on the current generated by the voltage-lowering transformer. This type of adapter is the type of adapter described in the above discussion. Equipment that still uses conventional adapters includes radio tape, amplifiers and so on.

2. Adapter Switching (SPMS)

The switching system adapter is a refinement of the conventional type of adapter which still has many weaknesses. Adapters with this system no longer use a step-down transformer like conventional adapters. the system in the circuit is very different from the conventional type of adapter.

About the discussion of this type of adapter will be discussed specifically in the next article.

Adapters that use switching systems include televisions, PC power supplies, laptop adapters, and other sophisticated equipment.

That’s a discussion about adapters, I hope it’s useful, if you have any input or questions, please submit them in the comment box provided.

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