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12V DC Power Supply: A Step By Step Guide

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. 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.  

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What is a 12V DC power supply?

A 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.  

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

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.  

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How do You Make a 12v DC Power Supply?

 Materials you will require

  • Vero board
  • LM7812 regulator
  • 1uF capacitor
  • Heat sink
  • Jumper wires
  • 100nF capacitors (2)
  • 1000uF to 4700uF capacitor
  • 1N4001 diodes (4)
  • Transformer 14V- 35V
  • Soldering iron
  • Wire strippers
  • Wire cutters

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

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.  


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.  


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

12v AC vs. 12v DC: What is the Difference Between AC and DC?

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

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

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.  


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.  


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.  


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.  


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

Can I use 12V AC Instead of 12V DC?

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 

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

Laptop charger power adapter


Typical Applications for 12VDC Power Supplies

  • Military
  • Medical
  • Motor control
  • Data acquisition
  • Analog and Data communications
  • Fiber optic and telecommunication networks
  • Power and utility industries
  • Educational facilities and universities
  • Computer peripherals
  • Electronics and instrumentation


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.    

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