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This question only involves the leaded components.

Electrolytic capacitors are each to recognize since they are usually in cylindrical cans. However, I am not sure about distinguishing the other two types, metal film vs. ceramic, if I come across a device others designed.

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  • \$\begingroup\$ What research have you done so far how to distinguish between them? Have you for example googled for images of ceramic and metal film capacitors? \$\endgroup\$
    – Justme
    Commented Nov 7, 2022 at 21:15
  • \$\begingroup\$ They don't look like each other. \$\endgroup\$
    – DKNguyen
    Commented Nov 7, 2022 at 21:16
  • \$\begingroup\$ If you relax the visually requirement, film capacitors don't exhibit significant voltage dependence--so if you measure the capacitance with a DC bias of nearly the rated voltage, a film capacitor will have about the same as its rated capacitance, while a ceramic capacitor, if it's a high-κ one (anything bigger than a nF will almost definitely be), it will have probably less than half its rated capacitance. Though if the ceramic cap has a C0G or U2J dielectric, it will look the same as a film cap to this test. \$\endgroup\$
    – Hearth
    Commented Nov 8, 2022 at 2:27

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Not answering per se, but adding an image to illustrate they can sometimes be ambiguous:

Capacitor lineup

Left: marking on top is "22K400∎". 22nF 10% 400V. Appears to be polypropylene (nice high Q factor). Unknown manufacture (salvaged). For reference, it's about 11 x 10 mm, 3.4mm thick.

Center: new (from a couple years ago) TDK FG22X7R1H225KNT06, a 2.2uF 50V 10% X7R ceramic. Basically an MLCC with leads welded on, dipped in epoxy. This is the smallest one here.

Right: 2.4nF 5% 100VDC polypropylene, possibly by TSC Group. Salvaged. Also pretty thin, but a noticeable bulge implying a wound rather than stacked or chip construction.

Most parts you will see in repair will be more obvious.

But this isn't a very design oriented question so I'll leave things at this.

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