How to Check Discharged Capacitors

A capacitor is an energy-storing device used in electronics. It stores energy as charge in plate conductors separated by a non-conductive dielectric. Whether it's charged or uncharged depends on the amount of electric charge contained in between the plates. It's charging when it absorbs electric current and discharging when it loses the absorbed electric current at a certain rate. The unit of measurement for capacitors is the Farad. Read on to learn more.

Difficulty: Easy

Instructions

Things You'll Need:

• Digital multimeter

1. Drain any residual charge in the capacitor by connecting it to Ground. All capacitors should be discharged before doing a test or soldering one into circuitry.

2. Ensure the terminals are intact. All capacitors have two terminals.

3. Take a digital multimeter that can measure capacitance. Ensure that it's turned off. Turn its mode switch to point to Farads. Plug the terminals of the capacitor into the holes provided on the multimeter. If the multimeter doesn't have insertion points, attach the multimeter probes onto the terminals of the capacitor.

4. Turn the multimeter on and read the capacitance on the LCD display. You may have to scale the capacitance level up or down before you see a number reading. If the multimeter is set to micro-Farads and the capacitor is in pico-Farads, the multimeter screen will display an out-of-range code.

5. Compare the reading given by the multimeter to the reading printed on the bulb of the capacitor. They should be comparable depending on the tolerance level.

Tips & Warnings

• Capacitors can be used as filters of high or low frequency signals.
• You can couple capacitors with inductors to form resonant circuits.
• High-voltage capacitors can deliver a shock that can range from painful to lethal.

Resources

• Online resource dedicated to capacitors