Voltage Regulator with MOSFET

MOSFET is a metal oxide semiconductor device that includes three terminals; gate, drain, and source. This MOSFET is mainly used for high-speed switching operations. The switching time of MOSFET is nanoseconds and its switching speed is extremely high. As compared to BJT, MOSFET is most frequently used because it doesn’t have any second breakdown occurrence, generates low heat, and has high efficiency. MOSFETs can be used as an amplifier, chopper, switch, and voltage regulator in many applications but they need special care while handling because they have electrostatic discharge problems. This article discusses how to design a circuit for a voltage regulator with MOSFET.

Voltage Regulator with MOSFET

The main objective of this is to design a voltage regulator circuit using MOSFET for regulating the output voltage depending on the fluctuations of input voltage.

Required Components

The required components to make a voltage regulator circuit with MOSFET mainly include; a 12V power supply, 12V bulb as load, switches SW1 & SW2, resistors R1 & R3 – 47K, resistor R2 – 1M, capacitor C1- 680nF, IRF3205 MOSFET.

Circuit Connections

The connections of the voltage regulator circuit with MOSFET follow as;

Voltage Regulator Circuit with MOSFET
Voltage Regulator Circuit with MOSFET

The positive terminal of the load is connected to the 12V power supply and the negative terminal of the load is connected to the drain terminal of IRF3205 MOSFET.

The SW1 switch positive terminal is connected to the load negative terminal through the R1 resistor.


The SW1 switch negative terminal is connected to the gate terminal of MOSFET through an R2 resistor.

The SW2 switch negative terminal is connected to the source terminal of MOSFET through the R3 resistor and the source terminal of MOSFET is connected to GND.

One terminal of the capacitor C1 is connected between the R1 & load whereas the other terminal is connected between the R2 resistor and the gate terminal of MOSFET.


The designing of a voltage regulator using MOSFET and some components is very simple which is shown above. This circuit uses two push buttons denoted with SW1 & SW2 which are used for controlling the power of o/p voltage. This voltage regulator is also called push-button voltage regulator because by using these two switches, the power can be increased or decreased within the output section.

Turn on the voltage regulator circuit & push any button, we can observe the main difference within the output. The load used in the output of this circuit is a 12V DC light. Once you press the SW1 switch this circuit will generate more current throughout the IRF3205 MOSFET to make the light ON. Similarly, when you press the SW2 switch, it will decrease the flow of current throughout the MOSFET to make the light OFF.


Voltage controller circuits using MOSFETs find a wide range of applications across various industries and electronic devices due to their efficiency, precision, and versatility. Here are some of the key applications:

  • Power Supplies:
    • Voltage controller circuits with MOSFETs are commonly used in power supplies to regulate output voltage. They ensure a stable and precise voltage level, making them suitable for everything from small electronic devices to industrial power supplies.
  • DC-DC Converters:
    • They play a critical role in DC-DC converters, where they convert one DC voltage level to another efficiently. This is crucial in battery-powered devices and renewable energy systems.
  • Motor Control:
    • In motor control applications, they are used to adjust the speed and direction of DC motors. This is commonly seen in robotics, electric vehicles, and industrial machinery.
  • LED Drivers:
    • LED lighting systems often incorporate these controllers  to regulate the voltage and current supplied to LEDs. This ensures optimal brightness and energy efficiency.
  • Solar Charge Controllers:
    • Solar charge controllers employ MOSFETs to manage the charging and discharging of batteries in solar power systems. They prevent overcharging and ensure efficient energy storage.
  • Battery Charging:
    • These are utilized in battery chargers, both for small devices like smartphones and for larger applications like electric vehicles and UPS (Uninterruptible Power Supply) systems.
  • Voltage Inverters:
    • These are used in voltage inverters, which convert DC power to AC power. These are fundamental in uninterruptible power supplies, solar inverters, and electric vehicle inverters.
  • Switched-Mode Power Supplies (SMPS):
    • SMPS use MOSFETs for voltage control to efficiently convert and regulate electrical power across a wide range of applications, including computers, telecommunication equipment, and consumer electronics.
  • Audio Amplifiers:
    • These are employed in audio amplifiers to manage the biasing and power supply voltage for amplification circuits, delivering high-quality audio output.
  • Heating Elements:
    • In applications like electric stoves, ovens, and industrial heaters, these are used to regulate power to heating elements, maintaining precise temperature control.
  • Welding Machines:
    • These are utilized in welding machines to control the welding current and voltage, allowing for fine adjustments during welding operations.
  • Variable Frequency Drives (VFDs):
    • VFDs in industrial settings use these to adjust the frequency and voltage supplied to electric motors, providing precise control over motor speed and energy efficiency.
  • Telecommunication Equipment:
    • They are used in power amplifiers and other components of telecommunication systems to regulate voltage and power levels.
  • Automotive Electronics:
    • In automobiles, they are used in various applications, including engine control units (ECUs), LED lighting, and battery management systems.
  • Aerospace:
    • These are used in avionics and spacecraft systems as well, where reliability and precision are paramount.

These diverse applications highlight the significance of voltage controller circuits using MOSFETs in modern electronics and industrial systems. Their ability to efficiently regulate voltage and power levels is pivotal in achieving optimal performance and energy efficiency across a broad spectrum of devices and industries.