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Voltage Divider in Electronic Circuit

Circuits-Voltage Divider
A Voltage Divider is a circuit or device that divides the total supplied voltage into fractions or parts among the various components or points in the device.

Voltage dividers are normally used to obtain various voltage output from a voltage source , For example in Transistor Biasing , Audio Circuits , Providing power to devices draining small currents etc.


Related Topics:
Circuits-Current Divider
Voltage Divider Circuit:

A voltage divider circuit is a circuit which divides the supplied voltage into fractions. Voltage Divider circuit consists of two or more resistor in series as shown in the figure below:

The figure above is a simple voltage divider which consists of a Voltage Source Supply of “V” and two resistors “R1″ and “R2″ , this circuit provides two output voltage “V1″ and “V2″ whose total sum is “V”.

Voltage Divider Rule:

The voltage divider rule is a simple rule which helps to determine the voltage drop or the voltage provided by a branch in a voltage divider circuit.

The rule simply stated that the voltage divided in each branch of a Voltage Divider circuit is in proportion to their resistance or impedance.

Or Mathematically:

Which is also called the voltage divider formula

Where ,

= Voltage along a branch (Let it be named X).

= Resistance of the branch X.

= Total Resistance of the branches in the Voltage Divider.

and , = Total Voltage supplied to the voltage divider.


Example 1:

In the following circuit:


The Voltage V1 divided in the upper branch =



and the voltage V2 divided in the lower branch =



Example 2:

In the Voltage Divider Below:

Resistance in Upper Branch = Equivalent resistance of 4 kilo ohms and Load resistance Rl = kilo ohms

Resistance in Lower Branch = 1 kilo ohms

So ,

and ,
 

Practicality of a Voltage Divider:

Voltage dividers are used in many types of electronics and electrical devices , Like Audio Circuits , Power Supply etc.

One of the major factor to be considered while designing a voltage divider is the value of the resistors to be used.

We can use any value of resistors in ratio to get the proportional output voltage. But it is good to use high valued resistors in a voltage divider because using low valued resistors dissipate more power from the main voltage source on heating resistors which cause fire or explosion and excessive use of power.

Because of the use of high valued resistors in voltage dividers which resists high amount of flow of current, Voltage Dividers are mostly used in electronics circuits that requires less than 10 mili amps of current.

Also as we can see in the example 1 and 2 above ; changing the load resistor value in a voltage divider might change the output voltage of a branch change massively , so voltage dividers should be designed specifically for a purpose or a load and cannot be used as a regulated power supply. One way to overcome this problem is to design the voltage divider such that the current flowing through the voltage divider circuit is about 10 times that of the current flowing through the load; using this approach helps to minimize the massive output voltage drop when connecting the load.

Thus care should be taken to balance the value of the resistors used in a voltage divider for the required purpose so that it is not too much to allow very less current though it which results in massive drop of output voltage with load; Nor it is too less to dissipate massive power through it which results in overheating and power loss.

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