# Voltage divider

### Why we need it?

In many projects we need sometimes  to divide the tension. One of the simplest forms is a voltage divider. They are basically two resistors connected in series. The input voltage “Vin” passes through the resistor “R1” and “R2” and goes to “GND”. The divided voltage is taken between the connection of the resistors “R1” and “R2”. This voltage depends on the values of the resistors “R1” and “R2” and the input voltage “Vin” .

Wikipedia: “A voltage divider is a configuration of an electrical circuit that divides the voltage of a source between one or more impedances connected in series. “

An example: We use a voltage divider in my Arduino Multimeter project. We need it because the maximum voltage that we can pass to an arduino input is 5 volts. For example, if we want to measure the voltage of 40 volts, we can not connect a voltage of 40 volts directly to the analog input of Arduino, so we have to lower the voltage. That’s why we use a voltage divider. In this example to be able to connect 40 volts to arduino we must choose the resistors “R1” and “R2” so that the output “Vout” does not exceed 5 volts. We can use this voltage divider calculator to calculate the values of the resistances. We have to introduce the input voltage “Vin” (in volts) and the values of the resistors (in ohms) and we will see the output voltage “Vout” (in volts). By changing the values of the resistors we can get the output voltage “Vout” that we need. In case of arduino “Vout should not exceed 5 volts.