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Voltage Regulator :

A transformer could use an easy feed-forward style or could embrace feedback. it’s going to use AN mechanical device mechanism or electronic parts. reckoning on the look, it’s going to be wont to regulate one or additional AC or DC voltages. Electronic voltage regulators are found in devices like laptop power provides wherever they stabilize the DC voltages employed by the processor and alternative components. In automobile alternators and central powerhouse generator plants, voltage regulators management the output of the plant.

Automatic voltage regulator :


The first automatic voltage regulators for generators were mechanical device systems, however, a contemporary AVR uses solid-state devices. associate degree AVR could be a feedback system that measures the output voltage of the generator compares that output to a collection purpose and generates a slip signal that’s accustomed alter the excitation of the generator. because the excitation current within the field coil of the generator will increase, its terminal voltage can increase.

The AVR can management current by victimization power electronic devices; usually, any low a part of the generator’s output is employed to supply current for the sector winding.

wherever a generator is connected in parallel with different sources like associate degree electrical transmission grid, dynamic the excitation has a lot off of control on the reactive power made by the generator than on its terminal voltage, that is usually set by the connected facility.

Electronic voltage regulators :


A simple voltage/current regulator may be made of an electrical device serial with a diode. thanks to the power form of diode V-I curves, the voltage across the diode changes solely slightly thanks to changes in current drawn or changes within the input. once precise voltage management and potency aren’t vital, this style could also be fine.

Since the forward voltage of a diode is tiny, this type of transformer is merely appropriate for low voltage regulated output. once higher voltage output is required, a Zener diode or series of a lot of zen diodes could also be used. Zener diode regulators build use of a lot of zen diodes fastened reverse voltage, which might be quite massive.

Any distinction is amplified and accustomed management the regulation part in such how on cut back the voltage error. This forms a feedback management loop; increasing the open-loop gain tends to extend regulation accuracy however cut back stability. there’ll even be a trade-off between stability and also the speed of the response to changes. If the output voltage is simply too low, the regulation part is commanded, up to a degree, to provide a better output voltage–by dropping less of the input voltage, or to draw input current for extended periods if the output voltage is simply too high, the regulation part can unremarkably be commanded to provide a lower voltage.

Solid State Voltage Regulator :


Voltage regulator, any electrical or device that maintains the voltage of an influence supply inside acceptable limits. … Electronic voltage regulators utilize solid-state semiconductor devices to rid variations within the flow of current.

A transformer is employed to manage voltage level. once a gradual, reliable voltage is required, then the transformer is that the most popular device. It generates associated fast|a set} output voltage that is still constant for any changes in an input voltage or load conditions. It acts as a buffer for safeguarding parts from damages.


Voltage Regulator IC 7805 :

Voltage sources in a very circuit might have fluctuations leading to not providing fastened voltage outputs. A transformer IC maintains the output voltage at a continuing price. 7805 IC, a member of 78xx series of fastened linear voltage regulators accustomed maintain such fluctuations, could be a standard transformer computer circuit (IC). The xx in 78xx indicates the output voltage it provides. 7805 IC provides +5 volts regulated power provided with provisions to feature a conductor.


Pin Details of 7805 IC :

  • Input voltage range 7V- 35V
  • Current rating Ic = 1A
  • Output voltage range VMax=5.2V ,VMin=4.8V
Pin No. Pin Function Description
1 INPUT Input voltage (7V-35V) In this pin of the IC positive unregulated voltage is given in regulation.
2 GROUND Ground (0V) In this pin where the ground is given. This pin is neutral for equally the input and output.
3 OUTPUT Regulated output; 5V (4.8V-5.2V) The output of the regulated 5V volt is taken out at this pin of the IC regulator.

This distinction between the input and output voltage is discharged as heat. The bigger the distinction between the input and output voltage, additional the warmth generated. If the regulator doesn’t have a sink to dissipate this heat, it will get destroyed and malfunction. Hence, it’s advisable to limit the voltage to a most of 2-3 volts on top of the output voltage.

7805 Regulator Features :

  • 5V Positive Voltage Regulator
  • Minimum Input Voltage is 7V
  • Maximum Input Voltage is 25V
  • Operating current(IQ) is 5mA
  • Internal Thermal Overload and Short circuit current limiting protection is available.
  • Junction Temperature maximum 125 degree Celsius
  • Available in TO-220 and KTE package

7805 Applications :

  • Constant +5V output regulator to power microcontrollers and sensors in most of the projects
  • Adjustable Output Regulator
  • Current Limiter for certain applications
  • Regulated Dual-Supply
  • Output Polarity-Reversal-Protection Circuit

Pin Diagram of 7805 :


As mentioned earlier, 7805 is a three terminal device with the three pins being 1. INPUT, 2. GROUND and 3. OUTPUT. The following image shows the pins on a typical 7805 IC in To-220 Package.

Pin 1 is the INPUT Pin. A positive unregulated voltage is given as input to this pin.
Pin 2 is the GROUND Pin. It is common to both Input and Output.
Pin 3 is the OUTPUT Pin. The output regulated 5V is taken at this pin of the IC.

Basic Circuit of 7805 :

About regulated power provide as a tool that works on DC voltages and it will uphold its output accurately at a hard and fast voltage all the time although there’s a big alteration within the DC input voltage.

As per the datasheets of 7805 IC, the fundamental circuit needed for 7805 to figure as an entire regulator is incredibly straightforward. In fact, if the input provide is Associate in Nursing unregulated DC Voltage,


In this circuit, VIN is the input voltage to the 7805 IC and the source can be from either a battery of an unregulated DC. VOUT is the output of the 7805 IC, which is a Regulated 5V.

Components Required :

  • 230V-12V Step Down Transformer
  • Bridge Rectifier (or 4 PN Diodes – 1N4007)
  • 1A Fuse
  • 1000µF Capacitor
  • 7805 Voltage Regulator IC
  • 0.22µF Capacitor
  • 0.1µF Capacitor
  • 1N4007 Diode