How to Build a Capacitor for a Known Value

Capacitors block direct current in electronic circuits.

A capacitor stores energy in an electric field. Capacitance, which is a capacitor's ability to store energy, is the ratio between the charge on the component's plates and the voltage between them. To build a capacitor, you must wire several smaller capacitors together. Each additional capacitor that you add decreases the larger capacitor's total capacitance. Although this appears to be less useful than either single capacitor, the larger capacitor can bear a higher working voltage.

Instructions

1. Divide 1 by the capacitance of the circuit's base capacitor. For example, if the base capacitor has a capacitance of 20 microfarads, divide 1 by 20 to get 0.05.

2. Divide 1 by the known value that you want for the total capacitance. For example, if this known value is 8 microfarads, then divide 1 by 8 to get 0.125.

3. Subtract the answer to Step 1 from the answer to Step 2: 0.125 minus 0.05 is 0.075.

4. Divide 1 by this answer -- 1 divided by 0.075 is 13.33. You must add a 13.33 microfarad component to build a capacitor with the known capacitance value.

References

• Georgia State University: Capacitor Combinations
• University of Cincinnati: Capacitors and RC Circuits

Resources

• Bucknell College: Capacitors
• University of Texas: Capacitors in Series and in Parallel