Electronic concepts-voltage and power

Electronic concepts:

Techparticipant presents Electronic concepts :In this post, you will read about other Electronic concepts by which you will able to

define voltage and power

Identify voltage and power requirements for different hardware devices.

Voltage and Power(fundamentals of electronics)

Voltage is the potential difference between a negatively charged component and a component with a positive charge.It is the “energy per unit charge”. It is measured in volts.

Power is the amount of electrical energy one unit time given by an electric circuit. measured in watts (W) or joules/second.

Voltage and power requirement by hardware devices(fundamentals of electronics)

A computer is an electronic machine, hence it can only be operated with a source of energy. It needs standard power and voltage range for its operation. Every electronic device or circuit is feed by the power supply unit(PSU).

Computer power supply voltages(fundamentals of electronics)

All hardware components present in a computer, require some amount of DC voltage to function. This amount may differ from a component. The following table lists a few components and their voltage requirement:

ComponentVoltage requirement(in volts)
Mainboard or motherboard12
USB ports3.3
Graphics cards5
CPU fan5

So, in a computer broadly three types of DC voltages are required, which are+12V, -12V,+5V,-5V and +3.3V.

Power ratings and voltage outside the permissible range can cause system failure.


A PSU draws the AC voltage from the source(generally from the socket) and converts it to the desired level of DC voltage. The following figure lists the parts found on the backside of PSU:

A point of connection for connecting the power cord to the computer.

A fan opening for drawing out the air from the power supply.

A red switch for changing the voltage of the power supply.

A rocket switch for turning on and off the power supply.

The following image shows a PSU:

Electronic concepts- Voltage and Power requirement
Electronic concepts- Voltage and Power requirement

There are different types of power supplies available in the market, but switched-mode power supplies are globally used today in personal computers.

There is also a stack of different colored cables inside a PSU.

The following figure lists the color codes of the PSU cables:

Black Wires

  • These wires are used to provide grounding.
  • Every other color should be paired with a black wire.

Yellow Wires

  • These wires denote +12V

Blue Wires

  • These wires denote -12V

Red Wires

  • These wires denotes +5V

White Wires

  • These wires denote -5V

Orange Wires

  • These wire denotes 3.3V

Green Wires

  • These are control wires to check the DC voltage

Purple Wires

  • These wires denote+5V on standby mode

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