Basically, a Voltage Reguator is a system that is deigned to automatically maintain a constant voltage. In detail, it is a component of the power supply unit that mainly ensures a steady constant voltage supply through all operational conditions in the circuit. It also regulates voltage during power fluctuations and variations in loads of electrical instruments. It can regulate both AC as well as DC voltages.

A voltage regulator usually takes in higher input voltage and emits a lower voltage which is more stable output voltage. Their secondary use is also to protect the circuit against voltage fluctuations or unconditional spikes that can potentially damage them.

Voltage regulators (VRs) keep the voltages from a power supply within a range that is compatible with the other electrical components. While voltage regulators are most commonly used for DC/DC power conversion, some can perform AC/AC or AC/DC power conversion as well.

There are 2 types of voltage regulators.

1. Linear

2. Switching Both types regulate a system’s voltage, but linear regulators operate with low efficiency and switching regulators operate with high efficiency. In high-efficiency switching regulators, most of the input power is transferred to the output without dissipation.

Electronic voltage regulators are found in devices such as computer power supplies where they stabilize the DC voltages used by the processor and other elements.

Voltage Regulator:-

• Voltage regualtor is a circuit which provides a constant d.c. voltage irrespective of variations in input voltage and load. Control element is the heart of the voltage regulator. Depending upon the connection between the control element and the load the voltage regulators are classified into two types. They are

1. Shunt Voltage Regulator.
2. Series Voltage Regulator.

• If the control element is connected in parallel with the load then the regulator circuit is called shunt voltage regulator.
• If the control element is connected in series with the load then the regulator circuit is called series voltage regulator.

Shunt Voltage Regulator:-

• The block diagram of shunt voltage regulator is given below.

• Unregulated input Vin is given to the voltage regulator. The input voltage Vin generates a current which is the sum of shunt current Ish through control element and Load current IL through Load.
• If the load voltage is increased due to any variations in unregulated input or load . Then the sampling circuit provides a increased feedback signal to the comparator circuit. The comparator circuit compares the feedback signal with reference voltage and the comparator circuit sends a control signal to the control element to draw more shunt current . Due to this load current decreases and hence the output voltage remains constant.
• If the load voltage is decreased due to due to any variations in unregulated input or load . Then the sampling circuit provides a decreased feedback signal to the comparator circuit. The comparator circuit compares the feedback signal with reference voltage and the comparator circuit sends a control signal to the control element to draw less shunt current . Due to this load current increases and hence the output voltage remains constant.
• Thus the voltage regulator provides a constant output voltage V0.