Voltage Divider

Voltage Dividing circuits are used to produce different voltage levels from a common voltage source, but the current is the same for all components in a series circuit.

Voltage Dividing Circuits areuseful in providing different voltage levels than a common feed voltage.This common feed can be a single positive or negative feed, usually according to 0V, such as +5V, +12V, -5V or -12V, etc., or through a binary feed. , for example, ±5V or ±12V, etc.

Voltage dividers are also known as potential dividers, since the voltage unit "Volt" represents the amount of potential difference between the two points.Voltage or potential divider is a simple passive circuit that benefits from the effect of voltages falling on serial connected components.

The pocinciometer,a variable resistance with sliding contact, is the most basic example of the voltage divider, as we are able to apply voltage to its terminals and produce an output voltage in proportion to the mechanical position of the sliding contact.However, since they are two-terminal components that can be connected to each other in series, we can also make voltage dividers using separate resistors, capacitors and inductors.

Resistant Voltage Divider

The simplest, easiest and most basic form of passive voltage divider network are two resistances connected in series.This basic combination allows us to use the Voltage Divider Rule to calculate voltage drops in each series of resistances .

Resistant Voltage Divider Circuit

voltage divider

Here the circuit consists of two resistances, which are connected in series: R 1 , and R 2 .Since the two resistors are connected in series, therefore, it should be concluded that the same electric current value should flow from each resistant element of the circuit, since it has nowhere else to go.This ensures an I*R voltage drop throughout each resistant element.

With a feed or weld voltage, V S can be applied against this array combination, using the Ohm law to apply the Kirchhoff Voltage Law (KVL) and also to find the drop on each Resistance derived from the voltage common current.

voltage divider

The current flowing through the serial network is simply I = V/R according to the Ohm Act.

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Likewise for R 1 resistance:

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Tension Divisive Question Example 1

When the feed voltage in the series combination is 12 volt dc, how much current will pass through the serially connected 20Ω resistance with 40Ω resistance.Also calculate the voltage drop produced in each resistance.

voltage divider

Each resistance provides an I*R voltage drop that is proportionally equal to the resistance value throughout the feed voltage.Using the voltage-dividing ratio rule, we can see that the greatest resistance produces the largest I*R voltage drop.Thus, R 1 = 4V and R 2 = 8V .Implementing Kirchhoff's Voltage Law indicates that the sum of voltage drops around the resistant circuit is exactly equal to the feed voltage, in 4V + 8V = 12V.

If we use two resistors of equal value, that is, R 1 = R 2 , then the voltage falling along each resistance will be exactly half the supply voltage for the two resistors in the series, since the voltage divider ratio will be equal to 50%.

Another use of a voltage dividing network is to produce variable voltage output. If we replace resistance R2 with a variable resistance (ponciometer), the voltage that falls along R2 and therefore VOUT can be controlled by an amount depending on the position of the ponciometer rod and therefore the ratio of the two resistant values. Ponsiometers, trimmers, reostas and variants are all examples of devices with variable voltage compartments.

By replacing constant resistance R2 with a sensor such as light-dependent resistance or LDR, we can take this idea of variable voltage division a step further. Therefore, as the resistant value of the sensor changes with changes in light levels, the output voltage changes in a proportionate amount. Thermisors and strain gauges are other examples of resistant sensors.

Since the above two voltage split expressions relate to the same common current, mathematically they must therefore be related to each other. Therefore, for any number of individual resistances that form a serial network, the voltage that falls along any given resistance is given as follows:

voltage divider
Voltage Divider Equation

Where: V R(x) is voltage drop along resistance, R X is the value of resistance and R T is the total resistance of the serial network.

This voltage divider equation can be used for any number of interconnected serial resistance due to the proportional relationship between each resistance, R and corresponding voltage drop, V.Note, however, that this equation is given for a loadless network of voltage dividers with no additional resistant load attached or parallel branch currents.

Tension Divisive Question Example 2

Three resistant circuits of 6kΩ, 12kΩ and 18kΩ are connected in series via a 36 volt feed.Calculate the total resistance, the value of the current passing around the circuit, and the voltage drops in each resistance.

Data supplied: V S = 36 volts, R 1 = 6kΩ, R 2 = 12kΩ and R 3 = 18kΩ

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Voltage Divider Circuit

voltage divider

Voltage drops in all three resistors must be added to the supply voltage defined by Kirchhoff's Voltage Act (KVL).That is, the sum of voltage drops: V T = 6 V + 12 V + 18 V = 36.0 V is the same value as the supply voltage (VS) and is correct.Again, note that the greatest resistance produces the greatest voltage drop.

Voltage Touch Points on the Dividing Network

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Consider a long series of resistances connected to a voltage source, V S .There are different voltage stage points throughout the serial network, A , B , C , D and E.

Total serial resistance, total resistance, can be found simply by combining individual series resistance values that give R T value 15kΩ.This resistance value will limit the flow of the current throughout the circuit produced by the supply voltage V S

Individual voltage drops throughout the resistors are found using the above equations, so V R1 = V AB , V R2 = V BC , V R3 = V CD and V R4 = V DE .

Voltage levels at each stage node point are measured according to the soil (0V). Thus, the voltage level at point D will be equal to VDE,and the voltage level at point C will be equal to VCD + VDE. In other words, the voltage at point C is the sum of two voltage decreases along R3 and R4.

Also note that in this example, each output voltage point will be positive because the negative terminal of the voltage source is grounded etc.

Tension Divisive Question Example 3

1. If the serially connected resistant network is connected to a 15 volt DC feed, calculate the load-free voltage output for each stage point of the voltage divider circuit above.

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2.Calculate the loadless voltage output between points B and E.

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Negative and Positive Voltage Divider

In the simple voltage divider circuit, above all output voltages are referenced from a common zero voltage soil point, but sometimes it is necessary to produce both positive and negative voltages from a single source voltage source.For example, the different voltage levels in a computer power supply according to a common reference earth terminal are -12V, +3.3V, +5V and +12V.

Tension Divisive Question Example 4

Using the Ohm Law, if the total power supplied to the loadless voltage divider circuit is -12V, +3.3V, +5V and +12V, find the values of the R 1, R 2, R 3 and R 4 resistors required to produce these voltage levels, the power supply is 24 volt DC, 60 watts.

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In this example, the zero voltage grounding reference point is moved to produce the necessary positive and negative voltages while maintaining the voltage dividing network throughout the feed. Therefore, all four voltages are measured according to the fact that this common reference point at point D has the necessary negative potential of -12V relative to the soil.

So far, we have seen that serial resistant circuits can be used to create a network of voltage dividers or potential dividers that are widely available in electronic circuits. By selecting the appropriate values for serial resistors, any output voltage value lower than the input or supply voltage can be obtained. But we can also use (L) (C) capacitors and inductors to create a network of DC supply voltage resistance voltage dividers using resistors.

Capacitive Voltage Divider

As the name suggests, Capacitive Voltage Divider circuits produce voltage drops between capacitors connected to a common AC source in series.Usually capacitive voltage dividers are used to "lower" very high voltages to provide a low voltage output signal that can then be used for protection or measurement.Today, high frequency capacitive voltage dividers are mostly used in imaging devices and touchscreen technologies found on mobile phones and tablets.

Unlike resistant voltage dividing circuits running on both AC and DC sources, voltage splitting using capacitors is possible only with a sinusoidal AC source.This is due to the calculation of voltage division between serially connected capacitors using X C, the colora of capacitors connected to the frequency of the AC source.

From our tutorials on capacitors in AC circuits, we remember that capacitive reassurance, X C(measured in Ohms) is inversely proportional to both frequency and capacitance, and therefore is given with the following equation:

Capacitive Reactance Formula

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  • Here:
  • Capacitive Reactance in Xc = Ohm, (Ω)
  • π (pi) = 3,142 numeric constants
  • ε = Frequency in Hertz, (Hz)
  • C = Capacitance in Farad, (F)

Therefore, knowing the voltage and frequency of the AC source, we can calculate the colorances of individual capacitors, change them for the resistant voltage divider rule in the equation above, and achieve corresponding voltage drops on each capacitor, as shown.

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Using two capacitors of 10uF and 22uF in the series circuit above, we can calculate the rms voltage drops in each capacitor according to their reassurance when connected to the 100 volt, 50Hz rms feed.

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When pure capacitors are used, the sum of all serial voltage drops is equal to the welding voltage, as with serial resistors.While the amount of voltage drop on each capacitor is proportional to its reactance, it is inversely proportional to its capacitance.

As a result, the smaller 10uF capacitor has more reassurance (318.3Ω), so a larger voltage drop of 69 volts occurs compared to the larger 22uF capacitor, which has a voltage drop of 144.7Ω and a voltage drop of 31 voltage, respectively.

One final point regarding capacitive voltage dividing circuits is that unless there is serial resistance, which is completely capacitive, two capacitor voltage decreases of 69 and 31 volts will arithmetic equal to a feed voltage of 100 volts. capacitors are in the same phase as each other.If for some reason the two voltages are out of phase with each other, then we cannot simply collect them, as we did when using the Kirchhoffs voltage law, instead the addition of phasers of the two waveforms will be necessary.

Inductive Voltage Dividers

As the name suggests, Inductive Voltage Dividers create voltage drops between inductors or coils that are serially connected to a common AC source.An inductive voltage divider can consist of a single winding or coil divided into two sections, from which the output voltage is taken from one section or two separate coils connected to each other.The most common example of inductive voltage divider is the automatic transformerwith multiple stage points along the secondary winding.

When the constant state is used with DC sources or with very low frequency sinusoids approaching 0 Hz, inductors act as short circuits.This is due to the fact that their reactance is almost zero and allows any DC current to easily pass through them, so as with the previous capacitive voltage dividing network, we must perform any inductive voltage chamber using a sinusoidal AC source.Inducers can be calculated using the inductive voltage section, inductors, colorance X L capacitive inducing among the connected series, depending on the frequency of the alternating current supply.

In training on inductors in AC circuits, we found that inductive coloract, X L(also measured in Ohm) is proportional to both frequency and inductive, so any increase in feed frequency increases inductor coloring.Thus, inductive reassurance is defined as follows:

Inductive Reactance Formula

voltage divider
  • Here:
  • Inductive Reactance in X L = Ohm, (Ω)
  • π (pi) = 3,142 numeric constants
  • ε = Frequency in Hertz, (Hz)
  • L = Induct in Henry, (H)

If we know the voltage and frequency of the AC source, we can calculate the coloring of the two inductors and use them in contingent with the voltage divider rule to achieve voltage drops in each inductor, as shown.

Inductive Voltage Divider

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Using two inducers of 10mH and 20mH in the series circuit above, we can calculate the rms voltage drops in each capacitor in terms of their reaccess when connected to the source of 60 volts, 200Hz rms.

voltage divider

Like previous resistant and capacitive voltage splitting circuits, the sum of all serial voltage drops throughout the inductors will be equal to the welding voltage, unless there is serial resistance.It means a pure inductor.The amount of voltage drop in each inductor is proportional to its colorance.

The result is that the smaller 10mH inductor has less reassurance (12.56Ω), so if it is 25.14Ω of color, respectively, and there is a less voltage drop of 30 volts compared to the larger 20mH inductor, which has a voltage drop of 40 volts.The current in the serial circuit is I L 1.6mA and since these two inductors are connected serially, it will be the same value for L 1 and L 2.

Tension Divider Summary

Here we found that the voltage divider or grid has a very common and useful circuit configuration that allows us to produce different voltage levels from a single voltage source, thus eliminating the need to have separate power supplies for different parts of a circuit running at different voltages.

As its name suggests, a voltage or potential divider "divides" a constant voltage to precise proportions using resistors, capacitors or inductors.The most basic and widely used voltage divider circuit is two fixed-value serial resistance circuits, but a pocinciometer or reosta can also be used for the voltage section simply by adjusting the wiper position.

A very common application of the voltage dividing circuit is to replace one of the fixed-value resistors with a sensor.Resistant sensors that change resistance values when responding to environmental changes, such as light sensors, temperaturesensors, pressure sensors and strain gauges, can all be used in a voltage dividing network to provide an analog voltage output.The polarization of bipolar transistors and MOSFeTs is another common practice of voltage divider.