---
title: "Capacitors"
question: "Which kind of capacitor should feed a load?"
url: "https://nearfieldnotes.com/videos/capacitor-types/"
site: "Near Field Notes"
video: "https://nearfieldnotes.com/media/capacitor-types/full.mp4"
duration: "2:39"
date: "2026-11-07"
note: "https://nearfieldnotes.com/notes/capacitor-types/"
---

# Capacitors (video)

Which kind of capacitor should feed a load?

2:39, with sound. [Read Note 13](https://nearfieldnotes.com/notes/capacitor-types/) for the full answer, with figures, conditions and sources.

## Transcript

Marked 22 µF. At its rated 25 V, it's down to 1.8.

Every kind of capacitor has a catch like this. Here are six, cut open and to scale.

Each gets two tests. Run 1 mW for as long as it can, and take a 1 A spike.

1. The MLCC. Hundreds of nickel plates, stacked in ceramic.

Charge sits on the plates, and the ceramic's dipoles line up. At high volts they already have, so each volt stores less.

Lowest resistance here. Tiny, cheap, and no polarity.

But it loses capacitance with voltage, and cracks fail short.

Use it to decouple chips and regulators.

2. Polymer tantalum. A sponge of tantalum grains, filled with polymer.

An oxide skin on every grain is the dielectric, and the sponge has a huge surface.

It keeps all 100 µF at any voltage, with low resistance.

But it's polarized, and it leaks the most of the six.

Use it for bulk on low-voltage rails.

3. Aluminum electrolytic. Etched foil, rolled up with paper soaked in liquid.

The foil grows an oxide skin, and ions in the liquid carry charge right up to it.

It's cheap capacitance at high voltage, and the oxide heals itself.

But it's polarized, and it dries out. Every 10 °C hotter halves its life.

Use it for bulk smoothing, kept cool.

4. The supercap. Porous carbon, in a liquid full of ions.

No oxide, no ceramic. Ions pile up a few atoms from the carbon, on a huge surface.

1 farad in an 8 mm can, and half a million cycles.

But a cell tops out at 2.7 V, so stacks need balancing.

Use it for hold-up and backup.

5. The lithium-ion capacitor. Half supercap, half battery.

One side holds ions on carbon. The other soaks lithium into graphite.

19 times the supercap's energy for its size, and it barely leaks.

But it must stay above 2.2 V, and you can't reflow it.

Use it for backup with bursts of amps.

6. A battery that looks like an MLCC. TDK's CeraCharge.

Lithium ions cross solid ceramic between the layers, like a stack of tiny cells.

It reflows with the rest of the board, and there's no liquid inside.

But it's 1.5 V, good for only milliamps, and it costs $11.

Use it to keep a clock alive.

On the same 1 mW load, they last from 1 second to 40 hours.

On a 1 A spike, the MLCC drops least for the first third of a microsecond. Then the tantalum, then the supercap, then the lithium-ion cap.

The electrolytic never drops least, and the chip battery can't take it.

Each one owns a time scale. Pick by how long your load lasts.

---

Source: https://nearfieldnotes.com/videos/capacitor-types/