Capacitor Identification – What is the Symbol with a uF Rating?


This circuit diagram has a symbol I've been unable to identify, which I've indicated with a stylish green arrow. I'm guessing some sort of capacitor based on the uF measurement, but I haven't been able to confirm that in my search through general circuit symbol lists or for capacitor symbols. Can someone clue me in?

circuit diagram with unknown symbol

Best Answer

It's an electrolytic capacitor. These are polarized, as the + sign also indicates. This is a less common symbol. Below are the more common ones, European on the left, American on the right.

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Compare to the symbol for a non-polarized capacitor:

enter image description here

Note: I think the American symbol for a non-polarized cap is a bad one; it suggests that there is some kind of asymmetry where in reality there isn't one.

From the comments it appears that the supposedly American non-polarized symbol is less common than I thought. I can only speak from my experience, and like I also said in comment, it could be that I've been looking mostly at older schematics (not the tubes, I'm not that old).
I found this schematic within a minute:

enter image description here

C2 might be an electrolytic (it won't be, will have a too low capacitance), but look at variable capacitor C1.
Also this page.

edit 2
Browsing through more symbols encountered also this weirdo (the one on the right):
enter image description here