AC to DC 12V Converter Circuit

In this article I discuss AC to DC Converter 12v Circuit, here there are mainly two types of converters widely used for AC-DC conversion purposes. The traditional transformer-based linear converter uses a simple diode bridge with a capacitor voltage regulator.

An AC to DC 12V converter is a device that converts Alternating Current (AC) to Direct Current (DC) with a voltage output of 12V. This is useful in applications where a DC voltage source is required, but only an AC source is available. The converter is typically used in automotive, industrial, and household applications.

A simple Diode Bridge can be constructed either with a single semiconductor device like DB107 or with 4 independent diodes like 1N4007. The other type of converter is SMPS (Switch mode power supply) which uses a high-frequency small transformer and a switching regulator to produce DC output.

In traditional Transformer-based design, we are using simple diodes and capacitors to convert the Alternating current into Direct Current. An optional voltage regulator to regulate the output DC voltage from AC. The project will be an AC-DC converter using a Transformer with an input voltage of 230V or 220V and an output of 12V, 1A.

Also Read: Difference Between AC and DC Currents | AC and DC Waveforms

220v to 12v dc converter circuit diagram

AC to DC Converter 12v

The above 220V to 12V DC Converter Circuit is simple, and the transformer is used to reduce the AC voltage. Four general-purpose 1N4007 diodes are used in this circuit to rectify the AC input by connecting the bridge, also known as the Bridge Rectifier. 1N4007 has a peak repetitive reverse voltage of 1000V and an average rectified forward current of 1A. These four diodes are used to convert the alternating current voltage to the direct current voltage. Actually, the transformer’s output is probably around 13V AC (unregulated), which is fed to the bridge rectifier to generate DC voltage. The diodes are used to build a bridge converter, which is an essential component of the 12v AC to DC converter circuit, in the circuit shown in the figure

What Is Bridge Rectifier

A bridge rectifier is a device that converts AC to DC electricity. It is used in many home appliances such as air conditioners, washers, dryers, and even some power tools. The bridge rectifier is a DC-DC converter that converts input AC to a lower DC voltage, which may be used for power input to a load

AC to DC Converter Circuit Working:

A step-down transformer is used to convert the high voltage AC to the low voltage AC. The transformer is PCB mounted and it is a 1-ampere 13-volt transformer. However, during the load, the transformer voltage drops approximately 12.5-12.7 volt.

The essential part of the circuit is a diode bridge which consists of four diodes. The diode is an electronic semiconductor device that converts the alternating current to a direct current.

AC to DC Converter Device Name

The device used to convert AC to DC is a Rectifier. As the name suggests, the rectifier corrects or straightens the direction of the current. The device periodically reverses the direction of alternating current (AC) to direct current (DC), which usually flows in one direction.

Components Required for AC to DC Converter 12V Circuit

Transformer with 1A 13V Rating
4 No.s – 1N4007 Diodes
A 1000uF Electrolytic capacitor with a 25V rating.
Few single strand wires
Breadboard
LDO or a Linear Voltage Regulator as per specification (Here LM2940 is used).
A multimeter to measure the voltage.

220v to 12v AC to DC converter Circuit using 7812 IC

Limitations of Transformer-based AC to DC Converter Circuit

Transformer-based AC to DC conversion is a common choice where DC is required but it has certain drawbacks.

In any situation where the input AC voltage has the possibility to fluctuate or if the AC voltage drops significantly, the output AC voltage across the transformer also gets dropped. So a 230V AC to 12V DC converter cannot be powered in a 110V AC line. To address this issue, an additional setting is provided for different input voltage levels.
Despite not having a universal input voltage range, it is a costly choice, as the transformer itself costs more than 60% of the total manufacturing cost of the converter circuit.
Another limitation is low conversion efficiency. The transformer gets heated up and wastes unnecessary energy.
The Transformer is heavy stuff which unnecessarily increases the weight of the product.
Due to the transformer, a bigger space is required inside the product to fit the converter circuit or at least the transformer.

Different Types of AC to DC Converters

We already know that AC to DC converters is also known as rectifiers, in this section, we will discuss uncontrolled rectifiers, of which there are four types…

Single-phase half wave rectifier

Single phase full-wave bridge rectifier

Single-phase center tapped full wave rectifier

Three phases half-wave diode rectifier

Single Phase Half wave Controlled Rectifier

In a single-phase half-wave rectifier, the negative or positive half of the AC voltage flows, while the other half of the AC voltage is blocked. Therefore, the output receives only half of the AC wave. here a single diode is enough for this rectification.

Single-phase half-wave rectifier Circuit

During the positive half cycle, the diode is in forwarding bias condition and maintains current up to RL (load resistance). A voltage is developed across the load, which is similar to the input AC signal of a positive half cycle.

Single-phase full-wave bridge rectifier

The single-phase full-wave rectifier does this by using four diodes arranged in a bridge arrangement passing the positive half of the waveform as before but inverting the negative half of the sine wave to create a pulsating DC output.

Single-phase-full-wave-bridge-rectifier circuit

single-phase full-wave diode rectifiers contain the following important parameters from Industrial Datasheet

Peak repetitive reverse voltage VRRM;
Ripple factor;
RMS input voltage per transformer leg VS;
Diode average current IF(AV);
Rectification ratio;
Output ripple frequency fr;
Peak repetitive forward current IFRM;
Transformer rating primary VA;
Diode RMS current IF(RMS) ;
Form factor;
Transformer rating secondary VA;
The form factor of diode current IF(RMS)IF(AV).

Single-phase Center Tapped full-wave rectifier

To overcome these limitations, SMPS or switch mode power supply is a preferable choice.

220V AC to 12V DC Converter Price:

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AC to DC Converter 12V Circuit Diagram, 220v to 12v DC Converter Circuit