Blog  /  DC Voltage: A Detailed Overview on How DC Works

DC Voltage: A Detailed Overview on How DC Works

As a budding computer hardware engineer, the mechanisms around the DC voltage and current may seem confusing. However, it's undoubtedly a popular fact that they both function as power outlets in the home and commercial space. Not to mention, they flow consistently in the same direction.

However, there’s more to these power sources than basic knowledge. Therefore, this comprehensive guide provides an in-depth look at everything that borders on DC voltage and current.

Let's find out how it works!

1. What are DC voltage and DC?

The DC in voltage and current stands for “direct current” or “constant polarity”. A  DC voltage is a constant voltage that drives the current in one direction. This means the current flows in one direction. However, it can vary in time. Rectifiers, solar panels, as well as batteries all, produce DC voltage from a chemical reaction.

A voltmeter measures the DC voltage levels. There are also several DC voltage power sources in use. For instance, most logic circuits, flashlights, trucks, and cars use a DC power supply. DC flow of current is present in anything. Meanwhile, the electric charge in DC has one direction of flow.

Furthermore, most digital electronic devices use DC electrical power. DC, in fact, converts the chemical energy in a battery to electrical energy. It also moves electrons from the point of negative charge to positive control without changing direction. 

Flow of current of DC and AC

(Flow of current of DC and AC)

2. The symbol for Direct Current

Since DC is constant, the symbol is a straight line. A straight line certainly means that the current is unidirectional. The figure below shows an illustration of the DC circuit.

Flow of current of DC and AC

(Direct Current DC Symbol Sign)

3. How to Measure the DC

The simplest way to measure a DC is with a digital multimeter. Current measurements are often easy to take. Below are simple steps on how to measure DC:

  • Firstly, connect the black probe of the multimeter into the COM Jack.
  • Then, put the red probes in the V Jack. After this, in reverse order, remove the red probe first, then the black searchlight black probe should connect to the negative polarity circuit ground and the red search to the positive test point.
  • Put the type of DC in the multimeter and read the measurement on display.

Another way to measure the DC flow of charge through a conductor is by using a clamp-on-meter.

Direct Current DC Symbol Sign

(A clamp-on-meter for measuring voltage)

4. Calculation of DC Power

Step 1:

Using ohm's law, you can specifically calculate the current (l), resistance ®, and voltage (V) of a DC circuit. With the result, you can then subsequently calculate the output power at any point in the circuit. Ohm's law formula is  Voltage (V) equals Current (I) times Resistance (R).

V = I x R



For example, if current (I) is 0.6 amps - DC (600 milliamps), R is 150 ohms. Using the formula above to calculate the maximum voltage: 0.6 x 150 = 90 volts. Moreover, in a situation, resistance measurement is unavailable, and it’s ideal to use the 4-wire mode measurement timing for accurate precision. 

Step 2:

To calculate DC power: Power (watts) = Voltage (volts) x Current (amps).

P = V x I

From step 1, P = 90 x 0.6 A = 54W.

calculation of DC power

(calculation of DC power)

5. The Difference Between AC and DC

Electrical energy comes in two forms: direct current (DC) and alternating current (AC). Both powers are essential for the functioning of all electrical devices. However, these forms of energy differ in application, signals, mode, amongst other things.

Difference between Alternating Current and Direct Current is shown

(Difference between Alternating Current and Direct Current is shown)

The significant difference between AC and DC power, and it’s in the comparison chart below;

Direct current (DC) Alternating current (AC)


The frequency of the direct current is 0Hertz (Hz). Since DC doesn't move in a waveform like AC, it has zero frequency because it has a unidirectional flow.  The frequency of AC shows how many times it reverses its direction. For example, the most popular AC frequency is 60 cycles per second, commonly known as 60 Hertz (Hz). So if the frequency is 55 Hertz, the current changes direction 55 times.

The direction of current flow

When a direct current flows through a circuit, it never changes direction in particular.  When alternating current flows through a circuit, it periodically reverses direction. In like manner, it also creates a spinning wire loop in a magnetic field.

Electron motion 

The electrons surely move in a fixed direction without changing. The electrons flow back and forth in an alternating direction.

Current size

The DC remains a constant magnitude for time. However, with a pulsating DC, it has a varying extent. The magnitude of AC particularly varies continuously concerning time.

Passive parameter

Only resistance. Impedance. This includes both reactance and resistance.

The Power factor

It is invariably 1. It falls between 0 to 1.


DC is usually converted to AC with a rectifier. AC converts to DC by using an inverter.


DC is often classified into pulsating and pure DC. Sinusoidal, Square, Trapezoidal, and a Triangle wave.


It has no waveform. AC waveform truly alternates. The waves form when alternators at power plants make AC power.

The load type

It only connects with the resistive type of load. On the contrary, Ac voltage connects with the capacitive, inductive, and resistive types of load.


DC electrical power is more hazardous compared to AC for a similar rating.  When handled carelessly, it is undoubtedly hazardous.


Cell phones, Flat-screen TVs, Flashlights, electric and hybrid vehicles, etc. Household and industrial appliances like dishwashers, refrigerators, and toasting machines use AC.


It uses both a DC battery and a generator. On the other hand, it uses an AC circuit and generator.

Electrical energy transmission 

In power or electrical source, the most current transmission system is through an HVDC. Besides, In this system, DC has a low voltage loss. It is also transmittable through the HVDC. 


Super efficient  It has low efficiency.

Sweep types 

This current source mode usually calculates the circuit bias point of selected power sources in predefined stages over a range of voltage values. Additionally, DC sweep also works alongside any source that has a DC variable. AC sweep simulation is specifically for calculating the small-signal response of a circuit voltage.

Scan type 

The scan speed is between 100 ms and 10,000 s. It also functions in a ramp or triangle wave.  This scan type ordinarily performs an at-speed sample cycle to ascertain timing compliance.

5. Application of Direct Current

Presently, DC source modes are solar cells, thermocouples, batteries, as well as fuel cells. Unlike AC which is the best pick for power plants and the electrical grid, various applications use this common type of power. 

Additionally, DC primarily functions in all consumer electronics. It is helpful in several applications like Cell phones, Flat-screen TVs, LED lights, electric and hybrid vehicles. Furthermore, it mainly works in applications with low volts, such as aircraft and charging batteries. Most energy mass storage devices are also DC-based. 

Direct current also transmits electricity with greater efficiency over a vast distance. DC applications and technology are not only very reliable, but they last for hours. Besides, in the PV industry, DC power supplies off-grid appliances and portable solar systems electric energy. The direct high-voltage current (HVDC) also uses DC to transmit electricity to bulk power systems like wind turbines.

hybrid vehicle using DC

(hybrid vehicle using DC)

6. Advantages and Disadvantages of DC

Formerly AC voltage current was often a form of energy suitable for power dissipation. But today, DC is emerging in the technological area. As a result, it can create job opportunities, increase research, inspire innovation, and stimulate economic growth. 


The most significant advantage of DC over AC is its ability to perform in particular applications certainly. For example, DC is preferable when there is an AC voltage drop for extended coverages. Listed below are the advantages and disadvantages of DC.

DC electrical motor

(DC electrical motor)



  • It is easier and faster to change the speed of a DC electric motor. 
  • DC indeed works in all consumer electronics.
  • Stores electric current. Again, DCsaves electricity in mass storage devices and small applications like the rechargeable battery and power banks. By storing electricity, it, in fact, becomes easily accessible when the renewable sources are not providing energy after the daylight hours. 
  • Better age regulation because the voltage output drop is comparatively tiny. 
  • The resistance conductive materials are generally very effective.
  • Requires less insulation to function because the pressure on the conductor is small.

solar panel

(solar panel)


  • With high-level constant voltage inputs, it becomes difficult to generate DC because of communication problems.
  • The DC voltage system is also challenging to increase for high voltage transmission. 
  • DC circuit voltage and switches are expensive in appliances. Above all, they often have a gear warranty on defects in materials. 
  • The DC transmission setup is particularly complex. 
  • You can’t modify direct current voltage input. 

DC flow of current with a rechargeable battery

(DC flow of current with a rechargeable battery)


We have indeed given a comprehensive overview of DC constant voltage current and its advantages and disadvantages. With this, you should have a better understanding of DC and how it differs from AC. DC electric charge has a unidirectional flow, and it’s present in almost every electronic device. On the other hand, AC is cheaper and easier to transmit. 

Just like AC, it's becoming undoubtedly feasible in technology. If you plug most of your electronics into the wall socket, you'll certainly have to transform AC to DC. The application of these power dissipation sources depends on several factors and specifications. Rest assured, with this guide, you should find switching between any form of energy quickly.