Voltage Divider for LED Brightness Control

Objective

To learn how to use a voltage divider circuit to monitor the voltage level of a battery, which can indicate the battery's charge level.

Materials

• 1 x Battery (e.g., 9V battery or 12V lead-acid battery)
• 2 x Resistors (values depending on desired voltage division, e.g., 10kΩ and 10kΩ)
• Breadboard
• Jumper wires
• Multimeter
• Microcontroller or analog voltage sensor (optional, for real-time monitoring)

Circuit Diagram

Connect the circuit as shown in the diagram below. The voltage divider consists of two resistors in series, with the output voltage taken from the connection between them.

Theory

A voltage divider reduces the input voltage to a fraction of its original value. This is useful for monitoring battery levels without exceeding the input range of a microcontroller or sensor. The output voltage is calculated as:

V_out = V_battery * (R2 / (R1 + R2))

Using appropriate resistor values, we can scale the battery voltage to a level safe for digital circuits.

Procedure

1. Place two resistors (R1 and R2) in series on the breadboard.
2. Connect the positive terminal of the battery to one end of R1.
3. Connect the junction between R1 and R2 to the input pin of a microcontroller or to a multimeter for direct measurement.
4. Connect the other end of R2 to the ground terminal of the battery.
5. Power the circuit and measure the output voltage across R2. Optionally, use a microcontroller to read the voltage and display it on a screen.

Observations

Record the output voltage for various battery levels. Note how the output voltage corresponds to the battery voltage, which allows you to gauge the battery's charge state.

Conclusion

This experiment shows how a voltage divider can be used to safely monitor battery levels, providing a scaled voltage that is proportional to the battery's charge. This setup is especially useful in systems where direct measurement of high voltage levels is impractical.