What is the voltage divider, and how does it work?

  • Dec 26, 2019

The bulk of electronic components, such as chips, running at a relatively low voltage of 3-5V. Voltage power supply is generally higher - 9-12V. And for a stable operation of the device is necessary to lower the voltage to a desired level. If this is not done, the sensitive circuits may be damaged.

There are different ways of doing it and the simplest of them - use a linear voltage divider resistors. This method is often used in low-power circuits.

The device is a simple circuit which converts high voltage minimal. Apply power to the 2 series-connected resistor, we can get the output voltage, which is part of the input.

What is needed to make a perfect divider?

Two things that you should understand - the scheme and the equation for the calculation.

Examples of arrangements of dividers. We say that a resistor, which is fed the input voltage (Vin) - R1And a resistor connected to the ground R2. The fall in voltage R2 It called the output voltage Vout. It is part of the input and can be calculated from the parameters of the current and resistance.

The equation for calculating the output voltage assumes that the known input Vin and the values ​​of resistors R1 and R2.

In a series connection the current is the same at any point along the chain. Therefore, according to Ohm's law, Vout = I * R2

Consider the input voltage Vin. The resistors connected in series and the total resistance is: R = R1 + R2

Let us return to the Ohm's law: I = Vin / (R1 + R2)

Substitute the current value obtained in the equation for the output voltage:

We obtain the equation of the voltage divider. According to this output voltage is input part and share it equals the resistance R2 divided by the sum of R1 and R2.

Practical application of the voltage divider

When you create an electronic circuit may be required to source voltage smaller than those usually available in stores. For example, many remote control elements to withstand 5V, and the most common power source for such schemes is a battery 9 V.

Consider how easy it is to turn a battery into the 3-volt button battery for portable chain, provided that it does not consume much current:

  1. Connect via clamp "crocodile" 20-ohm resistor to the red wire battery connector.
  2. Similarly, connect the black wire to the 10-ohm resistor.
  3. Twist the free ends of the two resistances. For reliability, you can fix the twist grip.

4. Connect the connector to the battery with the correct polarity.

5. Push the wire of the voltmeter to the twisting and crocodiles. Watch out for polarity. The voltmeter shows 3V.

So we got with the help of the necessary divider 3-volt voltage.

In order to choose the right face values ​​of resistance, you can use the equation. And you can search the network online calculator that does this automatically.

When using a variable resistor, it is called a potentiometer, the voltage across the resistor becomes adjustable.

Potentiometers are used wherever AC power is required. This volume control, measuring and radio equipment.