How can a 50V 100 uF electrolytic be so small??

[watchmaker]

Electrolytic capacitors seem to have really shrunk over the years. Do they really hold up as well as a physically larger one?  What changed that made them possible?

Thanks.

Dewey

[golden_labels]

Depends on what you mean “smaller” and “larger”.

If you bought something, which looks like a 6.3 V 47 µF wet electrolytic capacitor from eBay, it probably is a 6.3 V 47 µF capacitor.

If you mean the reduction in size by 1/3 in each dimension over the past 30 years: materials science progressed greatly in that time. Thinner isolation layers, wet electrolyte replaced with polymers, better production process control. Just look at this wet electrolytic capacitor cutaway from over 10 years ago: can you see how much space the seal alone takes?

[Smokey]

... Some day, young EE students won't even know the joy of having one of those wet electrolytics explode from overvoltage with a BANG and glorious confetti paper eruption!

[David Hess]

Electrolytic capacitors seem to have really shrunk over the years. Do they really hold up as well as a physically larger one?  What changed that made them possible?

Manufacturing got better, but their smaller case size limits their ripple current rating.

[watchmaker]

Thank you all.  "When I was a boy.......", if I recall correctly, we had electrolytic, ceramic and paper.  Today there is mylar, tantalum, polyester, mini electrolytics, and whatever else I do not know.  It was simple, electrolytics in PSUs, ceramics in coupling and bypass, and paper for oscillator ckts.

Now it seems that the use of capacitors ( a very simple concept) has become extremely sophisticated.  I have followed (tried?) some of the threads regarding "esoteric" (to me) uses and now I am ready to continue my basic studies with the next topic being capacitors.  It now has tremendous relevance.  Much more to the topic than time constants!

This looks to me like it can be a more complicated subject than transistors!  I love it.

[wraper]

Electrolytic capacitors barely became any smaller in last 20-30 years. For a long time caps come in multiple size versions, most miniature ones have way lower lifetime on average. Before that, yes there was shrinkage, especially compared to stuff from say 1960s.

[Zenith]

The properties of capacitors are quite involved, although for most purposes you can ignore much of it. Cost and size are involved when choosing a part, as well as technical considerations.

If you have a copy of The Art of Electronics (Horowitz & Hill) they give a list of 15 capacitor types, with their advantages and disadvantages.

Generally for a given capacitance and voltage, they've become smaller over the years because of better materials and construction techniques.

[radiolistener]

joy of having one of those wet electrolytics explode from overvoltage with a BANG and glorious confetti paper eruption!

with a very disgusting smell

Some capacitors have very toxic and dangerous chemistry inside. For example old oil capacitors with polychlorinated biphenyls for motors and mains circuits, especially these which working temperature is more than 95 °C.

[wizard69]

What changed that made them possible?

SDI or Star Wars as it was sometimes called, resulted in a lot of money being funneled into capacitor technology.   Consider super capacitors we can get today, they are even more amazing for size.   In any event electrolytic caps have such a horrible reputation that many manufactures have been trying to resolve the reliability problem these caps have, so on going research for years.

On the flip side we have Chinese manufactures that are optimistic about their products.

[coppercone2]

thats what reagan was talking about, it trickled down into the capacitors. i was looking for that money for a LONG time. Some complex economic analogy involving gutters and water tables. I guess we got like a rain barrel from a severely flooded crapper. reagan (god) works in mysterious ways

I thought we might get ion beam carpenters saws, but at least we got something

[Smokey]

joy of having one of those wet electrolytics explode from overvoltage with a BANG and glorious confetti paper eruption!

with a very disgusting smell
...

At least it's not as bad as the cloud of nasty magic smoke that comes out of a dipped tantalum that turned into a candle.  That smell sticks around for days.