Capacitors are Simple, Right?

It is easy to dismiss passive components like resistors and capacitors as a boring subject. [James Lewis] of Kemet Capacitors would disagree. He gave a talk about capacitor tech that is both approachable and in-depth.

Like every other component we use, we always think of them as perfect. But just like wires have resistance and inductance that we often ignore, capacitors have different imperfect characteristics that you need to be aware of.

Ceramic capacitors, for example, lose capacitance over time. Different ceramic material have different temperature sensitivity. Aluminum capacitors don’t last forever. Voltage applied to a capacitor can change its value as much as 50%.

[James] also talks about polymer electrolytics and super capacitors. His burning question: Is there any truth to the old guideline that you should derate capacitors by 50%? Want to know what he thinks? Watch the video below. Speaking of burning, he tackles the touchy subject of tantalum capacitors. The image at the top is a test Kemet ran on their own parts at reverse polarity well beyond spec. All of them are blown but only some look burnt. That’s a mystery well worth watching the talk.

The presentation, by the way, was from the Hardware Developer’s Didactic Galactic — a recurring set of hardware talks held at Supplyframe’s San Francisco office (and, for the record, Supplyframe happens to own Hackaday). If you want to read more about capacitors, you might enjoy our recent coverage of capacitor types. If supercapacitors strike your fancy, you can always grab some lint and dog hair.

Filed under: hardware

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