Voltage Divider Tutorial For Novices

A voltage divider is a circuit that creates a smaller voltage from an enter voltage through the use of two resistors. You’ll see it in each easy and superior circuits on a regular basis. Right here’s the fundamental setup:

The basic voltage divider circuit

It’s helpful for instance for studying sensors like thermistors and photoresistors because it converts an unknown resistance right into a voltage. Or to cut back the amount of an audio sign through a potentiometer.

You will discover the output voltage by inserting the resistor values and the enter voltage into the next formulation:

V_{OUT} = frac{R2}{R1+R2} cdot V_{IN}

Or you should utilize the calculator somewhat bit additional down on this web page.

As soon as you know the way it really works, it’s a lot simpler to see how circuits work. And it’ll allow you to calculate voltages at many various factors in a circuit – which is commonly wanted to know it.

Voltage Divider System

This formulation is without doubt one of the few electronics formulation (along with Ohm’s regulation) that I take advantage of regularly.

It’s for locating the output voltage when you could have two resistors related like this:

The basic voltage divider circuit

The formulation for calculating the output voltage is:

V_{OUT} = frac{R2}{R1+R2} cdot V_{IN}

This is usually a helpful formulation to recollect. It is going to turn out to be useful usually. Or use the voltage divider calculator beneath should you favor the simple manner 😉

Voltage Divider Calculator

Fill within the enter voltage and resistor values within the voltage divider calculator beneath to search out the output voltage:

Voltage Calculator Diagram

We’ve added this calculator to a sensible voltage divider calculator web page which you could bookmark and are available again to sooner or later.

The place Do You Discover The Voltage Divider?

One instance of a voltage divider circuit is for studying analog sensors. For instance, the thermistor is a temperature sensor. It adjustments its resistance based mostly on the temperature. If you happen to join it with a recognized resistor worth in a voltage divider setup, you’ll get a voltage that will depend on temperature:

Voltage divider circuit with thermistor

Or you’ll be able to mix a recognized resistor with a photoresistor. The photoresistor adjustments resistance based mostly on the quantity of sunshine it detects. This manner, you could have a circuit that will increase or decreases the voltage based mostly on mild.

Photoresistor sensor circuit

You’ll be able to join the output of any of those circuits right into a comparator to examine it’s above or beneath a sure voltage. Then do one thing based mostly on that. For instance, if the temperature is above 40 levels, activate a fan.

Or join into an analog pin of an Arduino or a microcontroller and do cool stuff with it. Possibly activate a light-weight if the photocell signifies that it’s darkish?

Calculation Instance: Totally different resistor values

Let’s say we have now the next values:




Through the use of the formulation above we get

V_{out} = frac{470 Omega}{180 Omega + 470 Omega} * 6 V = 4.3 V

Calculation Instance: Equal resistor values

Now, let’s say R1 and R2 has the identical worth.

V_{in} = 6 V

R_{1} = R_{2} = 470 Omega

Through the use of the formulation above we get

V_{out} = frac{470 Omega}{470 Omega + 470 Omega} * 6 V = 3 V

Which means when the 2 resistors have the identical worth, the output is at all times half the enter.

Can You Use Voltage Divider as a Energy Provide?

You probably have a circuit that wants 4.5 V, may you utilize a voltage divider with two 500 Ω resistors to get 4.5 V out of your 9V battery?

Sadly, it’s not that simple.

Any circuit you wish to energy can have an inner resistance. So from the attitude of the voltage divider, no matter circuit you connect with the voltage output might be seen as a resistor (RLOAD) related in parallel with R2.

A circuit diagram with three resistors

If the interior resistance of the circuit (RLOAD) can be 500 Ω, what occurs?

Now, the R2 from the voltage divider formulation turns into the parallel resistance of R2 and RLOAD. Which is simply 250 Ω. If you happen to put this into the voltage divider formulation, you get an output voltage of 3V as a substitute of the 4.5V you wished.

For an influence provide, you need the voltage to remain on the chosen stage irrespective of if the circuit you join has a excessive or low inner resistance. That’s why the voltage divider isn’t generally used for energy provides.

As an alternative, you must use a voltage regulator.


What are your questions in regards to the voltage divider? Let me know within the remark part beneath.

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