Voltage Divider Tutorial For Freshmen

A voltage divider is a circuit that creates a smaller voltage from an enter voltage by utilizing two resistors. You’ll see it in each easy and superior circuits on a regular basis. Right here’s the essential 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 scale back the quantity of an audio sign through a potentiometer.

You could find the output voltage by inserting the resistor values and the enter voltage into the next components:

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

Or you need to use the calculator slightly bit additional down on this web page.

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

Voltage Divider System

This components is among the few electronics formulation (along with Ohm’s legislation) that I take advantage of regularly.

It’s for locating the output voltage when you’ve two resistors linked like this:

The basic voltage divider circuit

The components for calculating the output voltage is:

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

This generally is a helpful components to recollect. It’s going to turn out to be useful usually. Or use the voltage divider calculator under when you desire the straightforward manner 😉

Voltage Divider Calculator

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

Voltage Calculator Diagram

We’ve added this calculator to a sensible voltage divider calculator web page that you may 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 modifications its resistance primarily based on the temperature. When you join it with a recognized resistor worth in a voltage divider setup, you’ll get a voltage that relies on temperature:

Voltage divider circuit with thermistor

Or you may mix a recognized resistor with a photoresistor. The photoresistor modifications resistance primarily based on the quantity of sunshine it detects. This fashion, you’ve a circuit that will increase or decreases the voltage primarily based on gentle.

Photoresistor sensor circuit

You may join the output of any of those circuits right into a comparator to examine it’s above or under a sure voltage. Then do one thing primarily based 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: Completely different resistor values

Let’s say we’ve the next values:




By utilizing the components 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

By utilizing the components 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 employ a voltage divider with two 500 Ω resistors to get 4.5 V out of your 9V battery?

Sadly, it’s not that straightforward.

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

A circuit diagram with three resistors

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

Now, the R2 from the voltage divider components turns into the parallel resistance of R2 and RLOAD. Which is simply 250 Ω. When you put this into the voltage divider components, 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 degree regardless of if the circuit you join has a excessive or low inside resistance. That’s why the voltage divider just isn’t generally used for energy provides.

As a substitute, it’s essential use a voltage regulator.


What are your questions concerning the voltage divider? Let me know within the remark part under.


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