Capacitive Voltage Divider / Capacitor Voltage Divider

Capacitor voltage dividing circuits can be created as easily as they can be created from reactive components, fixed-value resistors.

However, like resistant circuits, capacitive voltage dividing networks are evenly affected by changes in the feed frequency of each capacitor in the serial chain, so the reactive elementseven if they use capacitors, they are not affected by changes in the feed frequency.

However, before looking at a capacitive voltage divider circuit in more detail, the capacitive reactance andwe need to understand a little more about how it affects capacitors.

In ourfirst content about capacitors, we found that one capacitor consists of two parallel conductive plates separated by an insulator, and there is a positive ( + ) load on one plate and a contrasting negative ( ) load on the other.We also found that when connected to a DC (direct current) source and the capacitor is fully charged, it blocks the flow of current through the insulator (called dielectric).

Capacitor Voltage Divider
Electrolytic Capacitor

A capacitor resists current flow just like a resistance, but unlike a resistance that emits its unwanted energy in the form of heat, a capacitor stores energy on its plates while charging and returns the energy to the connected circuit when it is discharged.

The ability to resist or "react" to current flow by storing loads on the plates of a capacitor is called "reactance", and since this reactance is related to a capacitor, it is called Capacitive Reactance (Xc) and, like resistance, reactance is measured with Ohm.

When a fully discharged capacitor is connected to a DC source, such as a battery or power supply, the shutter's recapitalizing is initially extremely low, and while the capacitor plates are folded and charged, the maximum circuit current flows from the capacitor for a very short time.

After a period equal to approximately "5RC" or 5 time constants, the capacitor's plates are fully charged to equal the supply voltage and no other current flows.At this point, the shutter to dc current flow is almost an open circuit at maximum in the mega-ohm zone, and therefore the capacitors block dc.

Now, if we constantly connect the capacitor to an AC (alternating current) source that reverses polarity, the effect on the capacitor is that its plates are constantly charging and discharging according to the alternative supply voltage applied.This means that a charging and discharge current always flows into and out of the capacitor plates, and if we have a current flow, we must also have a reassurance value to oppose it.But what value would be and what factors determine the value of capacitive reactance.

In the tutorial on capacitance and charging, we found that the amount of load (Q) found on the capacitor plates was proportional to the voltage applied and the capacitance value of the capacitor.Since the applied alternative supply voltage (Etc.) is constantly changing, the value of the load on the plates should also be changing.

If the capacitance value of the capacitor is greater, it takes longer to charge the capacitor as R, capacitor τ = RC for a certain resistance, which means that the charging current flows over a longer period of time.A higher capacitance results in Xc, a small reassurance value for a given frequency.

Similarly, if the capacitance value of the capacitor is small, a shorter RC time constant is required to charge the capacitor, which means that the current will flow for a shorter period of time.A smaller capacitance results in Xc, a higher reassurance value.Then we can see that larger currents mean smaller reassurance, and smaller currents mean larger reassurance.Therefore, capacitive reactax is inversely proportional to the capacitance value of the capacitor, X C-1 C.

However, capacitance is not the only factor determining capacitive reactance.If the applied alternating current is at a low frequency, it has more time for reactance to form for a given RC time constant and opposes the current indicating a large reactance value.Similarly, if the applied frequency is high, there is very little time between the charging and discharge cycles for reactance to form and resist current, which leads to a larger flow of current indicating a smaller reactance.

Then we can see that a capacitor is an impedance, and the size of this impedance depends on the frequency.Therefore, larger frequencies mean smaller reassurance, and smaller frequencies mean larger reassurance.Therefore, Capacitive Reactance , Xc (complex impedance) is inversely proportional to both capacitance and frequency, and the standard equation for capacitive reassurance is given as follows:

Capacitive Reactance Formula

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

Voltage Distribution in Serial Connected Capacitors

Now we have seen how the contrast to the charging and discharge currents of a capacitor is determined not only by the capacitance value, but also by the feeding frequency, let's look at how it affects the capacitive voltage divider circuit created by serial connection.

Capacitive Voltage Divider

Capacitor Voltage Divider

Consider two capacitors, C1 and C2, which are serially connected throughout a 10-volt alternating current feed.TwoSince the capacitor is serially connected, the Q load on them is the same, but the voltage between them will be different and will be associated with capacitance values in V = Q/C.

Voltage dividing circuits can be created from reactive components as easily as they can be created from resistors, since they both comply with the voltage dividing rule.For example, consider this capacitive voltage divider circuit.

Eachthe voltage on the capacitor can be calculated in various ways.A way like this, everyit is used to find the capacitive reassurance value of the capacitor, the total circuit impedance, the circuit current, and then calculate them the voltage drop.

Capacitive Voltage Divisive Question Example 1

Two 10uF and 22uF in the series circuit aboveusing a capacitor, each time it is exposed to a 10 volt rms sinusoidal voltage at 80 Hzcalculate rms voltage drops in the capacitor.

10uFcapacitive reassurance of the capacitor:

Capacitor Voltage Divider

22uFcapacitive reassurance of the capacitor:

Capacitor Voltage Divider

Total capacitive recess of the serial circuit – Note that the reassurance in the series is added to each other just like the resistors in the series.

Capacitor Voltage Divider


Capacitor Voltage Divider

Circuit current:

Capacitor Voltage Divider

Next, the voltage drop in each capacitor in the serial capacitive voltage divider will be as follows:

Capacitor Voltage Divider

When capacitor values are different, the smaller valuecapacitor self of great valueit will charge to a higher voltage than the capacitor, and in our example above this was 6.9 and 3.1 volts, respectively.Since Kirchhoff's voltage law applies to this and each series of connected circuits, the total value of individual voltage drops will be equal to the feed voltage, VS = 6.9 + 3.1 = 10.

Keep in mind that the rates of voltage drops between two capacitors connected to the serial capacitive voltage divider circuit will always remain the same regardless of the feeding frequency.Then in our simple example, the two voltage drops of 6.9 volts and 3.1 volts above will remain the same even if the feed frequency is increased from 80Hz to 8000Hz, as shown.

Capacitive Voltage Divisive Question Example 2

Calculate capacitive voltage drop at 8,000Hz (8kHz) using the same two capacitors.

Capacitor Voltage Divider

TwoWhile the voltage ratios between the capacitor may remain the same, the combined capacitive reassurance decreases as the feeding frequency increases, and therefore the total circuit impedance decreases.This decrease in impedance causes more currents to flow.For example, at 80Hz we calculated the above circuit current as about 34.5mA, but at 8kHz the feed current increased by 100 times to 3.45A.Therefore, the current flowing from a capacitive voltage divider is proportional to the frequency or I ∝ ε.

There's a.the capacitor divider is connected to the series, each with an AC voltage drop on itWe saw there was a network of capacitors.Capacitive voltage dividers are used to determine the actual voltage dropSince it uses the capacitive reassurance value of the capacitor, they can only be used in frequency-operated sources and therefore do not work as DC voltage dividers.This is because,the fact that capacitors block dc and therefore no current flows.

Capacitive voltage dividing circuits are used in a variety of electronic applications,from Colpitts Oscillatorsto capacitive touch screens that change the output voltage when touched by a person's finger.

As we now know, bothVoltage splitting throughout a capacitive voltage divider circuit will always remain the same, keeping the voltage constant, as the capacitor's recess changes with frequency (at the same rate).