12V DC Power Supply: A Step By Step Guide

Do you want to know what the 12V DC power supply is, how it works, its applications, and how you can make one at home?

In this article, you will find answers to all of the above questions, and we even offer you differences between the AC and DC.  

What is the Function and Significance of a 12v DC Power Supply?

A power supply

A 12VDC power supply is a device that supplies electrical energy to a load. In other words, a power supply's primary purpose is converting electric current from the source into the required voltage, frequency, and current, which powers the load.

The 12V DC power supplies fall into two categories, namely

• 12V regulated power supplies
• 12V unregulated power supplies

In addition, the 12V regulated power supply has three subgroups:

• Switching regulator AC to DC
• Linear regulator AC to DC
• Switching regulator DC to DC

Let us have a closer look at each.  

What Does 12 VDC Mean in Terms of Power Supply Voltage?

The 12V DC power supply is among the leading power supplies in today's technological world. Mainly because of its affordability, reliability, and ease of use. 12V DC Power supply voltage offers consistent performance, is cost-effective, and is simple to install and maintain. Its compatibility with various devices makes it a versatile choice for numerous applications across different industries.

Switching Regulated AC to DC

Switching regulated 12VDC power supplies are also known as switched-mode power supplies or SMPS power supplies.

These power supplies work by regulating the output voltage with a high-frequency switching process utilizing feedback with pulse width modulation.

Moreover, switching regulated power supplies run substantial EMI filtering to reduce the load and line's regular and differential noise.  

A regulated power supply

Source: Wikipedia   

For this 12V power supply, galvanic isolation is critical as it affords users input to output then output to ground insulation. Doing so ensures good versatility.  

Linear Regulator AC to DC

A linear regulated 12VDC power supply functions by regulating output with the help of a dissipative modulating circuit for effective performance.

As a result, these supplies are stable, contain low ripple, and do not switch frequencies to make EMI.

Likewise, the switching regulated AC to DC also employs galvanic isolation and is available in AC to DC outputs (wide or single).  

Unregulated 12VDC Power Supplies

These are basic power supplies with an unregulated 12VDC output and an AC input.

Consequently, the output voltage in an unregulated power supply varies depending on the load and input voltage. Most importantly, unregulated power supplies are affordable and highly reliable.  

 Materials You Will Require

• Vero Board - This provides a platform for mounting and soldering the electronic components to create the 12V DC power supply circuit.
• LM7812 Regulator -  The LM7812 regulator ensures a stable 12V DC output by regulating the input voltage from the transformer.
• 1uF Capacitor - Helps smooth out voltage fluctuations and improves the stability of the power supply.
• Heat Sink - This dissipates heat generated by the regulator, preventing it from overheating.
• Jumper Wires - used to connect various components on the Vero board, completing the circuit pathways.
• 100nF Capacitors (2) - These filter out high-frequency noise from the power supply, ensuring a clean output.
• 1000uF to 4700uF Capacitor - ooths the rectified DC voltage from the transformer, reducing ripple and providing a steady output.
• 1N4001 Diodes (4) - Forms a bridge rectifier, converting AC voltage from the transformer to DC voltage.
• Transformer 14V- 35V - Steps down the mains AC voltage to a lower AC voltage suitable for rectification and regulation.
• Soldering Iron - This is used to join electronic components to the Vero board by melting solder to form secure electrical connections.
• Wire Strippers - To remove the insulation from wires, preparing them for soldering or connection to components.
• Wire Cutters - To trim wires to the necessary length for making neat and efficient connections on the Vero board.

Circuit Diagram

Some points to note:

Firstly, to make a 5-volt power supply, you can use an LM7805 regulator instead of the LM7812.

Secondly, you will need a heat sink to realize 1 amp from this power supply.  

Heat sinks

Source: Wikipedia  

The heat sink protects the device against high temperatures that may lead to burnout.

However, if your target is less than 500mA, you can work without a heat sink.  

Start Building

Once you have assembled all the required materials, you can build your 12V DC power supply.

While building, remember to place the electric components precisely as indicated by the circuit diagram.

Above all, make strong solder joints with no solder bridges, or the power supply will be faulty.  

Testing

After making the power supply comes the most critical part of testing it. By checking it using a multimeter, you will see if there are any solder bridges.  

Multimeter 

Assuming you find no issues, you can now use the power supply as you deem fit.  

Firstly, let us define each type of currency.  

Alternating Current (AC)

Alternating current, known mainly by the masses as AC, is a type of current or voltage scale that has varying size and direction after some time.

Here is an alternating current waveform diagram  

AC/Alternating Current waveform

Direct Current (DC)

Direct current, also famously known as DC or constant current, is a current whose magnitude and direction remain constant.

Some of the DC sources include dry batteries or lead-acid batteries.  

DC/Direct Current waveform

We compared 12V AC power to 12V DC power regarding safety, use, measurement, and loss to find the difference between AC and DC.  

Differences Between 12v AC and 12v DC

DC works well for long-distance or immense capacity transmission, and as a result, HVDC transmission has grown in popularity.

On the other hand, alternating current contains inductance parameters hence a substantial loss during extensive transmissions.  

Use

Direct current is stable and does not make much noise; therefore, it can work well in electrical items like televisions and radios.

An alternating current must pass through a switching power supply and into DC to function on electronic products.  

Safety

Generally, the 12VDC is more secure compared to 12V AC. For instance, the human body has lower resistance when exposed to 12V AC power than 12VDC power.

Nevertheless, the degree of damage caused by electrical shock to humans largely depends on the duration of the energization.  

Peak

12V AC and 12V DC have varying peak voltages due to their respective voltage patterns.  

All AC or DC power adapters accept a specific AC input from the power source, converting it to a required DC output.

The DC output mainly released depends on the type of device, whether it's a speaker, phone charger, or laptop charger.  

Phone charger 

Therefore, when you use a 12V AC power adapter yet the device requires a 12V DC power adapter, then the device might encounter issues like

• Incorrect polarity
• Low voltage or high voltage

Experts recommend that you only use the required power adapters with the required voltages to avoid the above-stated problems.  

Laptop charger power adapter

Typical Applications for 12VDC Power Supplies

• Military -12V DC power supplies are crucial in military applications, powering communication devices, navigation systems, and field equipment. Their reliability and robustness ensure operational continuity in harsh environments. They are also used in portable systems due to their compact and efficient design.
• Medical - In the medical field, 12V DC power supplies power diagnostic equipment, patient monitoring systems, and portable medical devices. Their stable output is critical for accurate and reliable medical data. They ensure uninterrupted power supply, which is vital for life-saving devices.
• Motor Control - 12V DC power supplies are commonly used in motor control systems, providing the necessary voltage for small DC motors in industrial automation and robotics. They enable precise speed and torque control. Their efficiency contributes to the overall performance and longevity of motor-driven systems.
  
  
• Data Acquisition - 12V DC power supplies are commonly used in motor control systems, providing the necessary voltage for small DC motors in industrial automation and robotics. They enable precise speed and torque control. Their efficiency contributes to the overall performance and longevity of motor-driven systems.
• Analog and Data Communications - Data acquisition systems use 12V DC power supplies to operate sensors, data loggers, and measurement instruments. They provide the stable power needed for accurate data collection. Their reliability ensures consistent performance in various environmental conditions.
  
  
• Fiber Optic and Telecommunication Networks - In fiber optic and telecommunication networks, 12V DC power supplies power transceivers, switches, and repeaters. They ensure reliable data transmission over long distances. Their compact size and efficiency are ideal for network equipment.
• Power and Utility Industries - Power and utility industries use 12V DC power supplies for monitoring and control systems in substations and grid management. They ensure the stable operation of critical infrastructure. Their durability is essential for continuous and reliable service.
  
• Educational Facilities and Universities - Educational facilities and universities use 12V DC power supplies in laboratories for research and experimentation. They power various educational instruments and prototyping tools. Their affordability and ease of use make them ideal for academic environments.
  
  
• Computer peripherals - Educational facilities and universities use 12V DC power supplies in laboratories for research and experimentation. They power various educational instruments and prototyping tools. Their affordability and ease of use make them ideal for academic environments.
  
  
• Electronics and instrumentation - In electronics and instrumentation, 12V DC power supplies power testing equipment, measurement tools, and control systems. They provide stable and precise power necessary for accurate readings and reliable operation. Their versatility makes them a staple in laboratories and industrial settings.
  
  

Summary

After reading this article, we hope you can define an AC and DC and state their differences.

You should also be able to state the various categories and subcategories of the 12V DC power supply.

Most importantly, remember to follow the schematic diagram when making your power supply accurately and take the necessary safety precautions to avoid accidents.

Whenever you encounter any problems or need additional information on the subject, feel free to contact us.