Please help ID this capacitor

Can you help me ID a small capacitor. The photo shows two identical capacitors which are marked with:

225F *

Underneath that marking on the capacitor is a + sign followed by a long line.

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(1) Are they likely to be tantalum capacitors?

(2) Does that marking mean they are 220nF or are they 220pF? Or some other value?

Reply to
tommi
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2.2uf, voltage unknown. They sure look like tantalums.
Reply to
att

I've heard tantalum capacitors can get noisy or break down over time.

The device in my photo is used to power a microphone. So any noise from it would be very unwelcome.

Is it worth changing those capacitors to another type? Would something like a polyester capacitor have enough capacity for 2.2uF and still be physically small enough to fit in the space on the circuit board shown in my photo?

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Reply to
tommi

Those are 'orange drop' style tantalum capacitors. If it's used for power supply bypassing, there's no problem. If, however, it's used for DC blocking the capacitor could be in series with your microphone signal.

The seal of such capacitors is fragile (i.e. handling or aging can break 'em open), and a good axial-package aluminum might be more reliable...

I wouldn't replace it, myself, but it wouldn't be my first choice for the application.

Reply to
whit3rd

There could be other sources of noise. For example: no shielding in the plastic case. And are those carbon composition resistors? They can be noisy. I don't see any ceramic capacitors; those can be noisy due to piezoelectric effect.

Al

Reply to
alchazz

I've used tantalums (SMT version, but built basically the same internal construction as what shows in your picture) in an application where I rely on them being very quiet. The caps I use are operated at a fairly small fraction of their rated working voltage. The circuit has been in production for years, and I've never heard of a problem. Tantalums absolutely CAN have problems with noise, and I've run tests that show it readily, but my experience is that they are quiet between noise pulses and the noise pulses occur very seldom indeed if you operate at no more than, say, 1/3 the rated voltage.

Cheers, Tom

Reply to
K7ITM

I suggest you get better advice. Whilst ANY cap can do that, tantalums are better in this respect than standard electrolytic caps and I'd say from that pic, it wouldn't be remotely likely.

Graham

Reply to
Eeyore

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