How to Make a Voltage Divider Circuit

Modern electronics use two ways to reduce voltages, which depend on whether the voltage source is AC or DC in nature. For AC power, a transformer can step the voltage down to meet the requirements of the application. DC voltages however, require a resistor network to step the voltage down to meet the requirements. The resistor network forms a voltage divider to provide several voltages to the circuit.

Difficulty: Moderate

Instructions

Things You'll Need:

• Voltmeter
• 9V battery source
• 2 Resistors, 1000 ohm and 2000 ohm
• Snap cap for 9V battery
• Wire

1. Separate the red and the black wire that sticks out the end of the 9V snap cap. Construct the divider circuit without the 9V battery connected to protect you from getting shocked.

2. Select the resistors you need to divide the source voltage to the required voltage for the circuit. Digital electronics typically requires a voltage of between three and five volts. To drop the 9V battery down to 4.5 volts you need to use resistors where the ratio of their ohm values is two. A 1000 ohm resistor coupled with a 2000 ohm resistor will produce the desired voltage drop.

3. Connect one end of the 2000 ohm resistor to the red wire of the 9V snap cap. Make sure there is a firm connection between the resistor lead and the wire. Loose connections will produce a fluctuating voltage.

4. Twist the other lead of the 2000 ohm resistor with one of the leads on the 1000 ohm resistor. Again, make sure the leads are twisted together to make a firm solid connection.

5. Join the other lead of the 1000 ohm resistor to the black wire of the 9V snap cap. Make sure the connection is firm and solid.

6. Attach the 9V battery to the snap cap. You now have a voltage divider circuit to produce 4.5 volts at the point between the two resistors.

7. Check the voltage drop across the 1000 ohm resistor. The side of the resistor is ground. Attach the black lead of the voltmeter to the side of the 1000 ohm resistor that is attached to the black lead. Attach the red lead of the voltmeter to the point between the two resistors where the leads are connected. The meter will read about 4.5 volts. The exact reading will depend on the exact resistance of the two resistors and the exact voltage of the battery.