Understanding Voltage Divider

Just like the term, voltage divider means dividing the voltage into smaller value. Sometimes this is very useful if we had only measurement instrument with limited maximum value. Such as pocket oscilloscope.

Understanding Voltage Divider

Dividing voltage is very simple job but very powerful. We just need two resistor to do it. Here’s the example how we do it.

voltage divider
voltage divider

Consider we have 10V voltage, using two resistor will result 5v at the output. This is how we calculate it :

Vout = Vin * R1/(R1+R2)

So if we want to divide the voltage by 3. You can simply change the R2 to 2k. So the output will be :

Vout = 10 * 1k/(1k+2k) = 3,333 V

Voltage Divider Application Example

In some cases, voltage divider is very useful for signal conditioning. For example, you have to sense a voltage from a power supply using an arduino or other microcontroller. The power supply can generate voltage from 0V-50V. Unfortunately, your arduino can sense voltage only from 0V-5V. That’s why voltage divider come in handy. You can just divide voltage from power supply by 10. So the output will only produce voltage between 0V to 5V and you can read using arduino ADC easily.

Beside divide the voltage, you can use voltage divider to convert resistance based sensor to voltage. For example a light dependent resistor (LDR).

voltage divider with ldr
voltage divider with ldr

Take a look at picture above. We already know that LDR will vary the resistance by how much light that exposed to it. This will make easier to read voltage output from different light brightness.

Voltage Divider is not for Power Supply

If you are new to electronics and think to use voltage divider for power supply then you are wrong. Why not for power supply? Voltage divider works with big resistors, so it will produce very small current. Small current cannot used for power supply. You can user linear regulator or switching power supply instead.

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