76
votes
What happened to electrolytic capacitors in the 21st century?
There was a period of time where lots of capacitors were made with a dodgy electrolyte, especially by some large Taiwanese manufacturers. The capacitors looked OK in a wide variety of tests when new, ...
- 12.2k
50
votes
Accepted
Is the capacitor drawn or wired wrongly?
The capacitors marked red are too small to be electrolytic. They must be ceramic. They just used same symbol for all capacitors except without the plus sign.
- 159k
32
votes
What happened to electrolytic capacitors in the 21st century?
Industrial espionage gone wrong. Verified many years after the fact.
Though it was suspected from nearly the beginning. (Article courstesy of The Wayback Machine, since the original is gone from ...
- 72.5k
32
votes
Why are electrolytic capacitors still in production?
What are the advantages of using electrolytics?
Available with about 3 orders of magnitude higher capacitance at the same voltage rating
Capacitance is stable under DC bias, whereas most (Class 2) ...
- 17.6k
30
votes
Is the capacitor drawn or wired wrongly?
It's actually a common misconception that the curved side means negative or that the curve signifies an electrolytic. The + sign is supposed to be used to indicate polarity. Any specific meaning of ...
- 1,240
30
votes
Accepted
Why are electrolytic capacitors still in production?
Voltage rating would be the biggest difference as electrolytics are much cheaper if you need a higher voltage rating in the same value. But there are many different factors to compare and there are ...
- 84.8k
28
votes
Using capacitors as a battery back-up
If your operating power is 12 V * 8 A = 96 watts, and you want to run for 20 s, you need to be able to deliver 20x96 = 1920 J, which is a huge amount of energy for capacitors. Depending on the volume ...
- 169k
27
votes
Is the capacitor drawn or wired wrongly?
It looks like lazy symbol use. Those motor noise suppression caps and the crystal caps should be ceramic caps which are non-polarized. You'll have a hard time finding 33pF or 0.1uF electrolytic caps ...
- 56.9k
27
votes
Accepted
High short circuit failure rate of aluminum electrolytic capacitors during the production processes
That high a failure rate is unheard of for a top-quality supplier like Nichicon when properly assembled and operated conservatively. Even for no-name parts it’s not at all usual- one in 10,000 might ...
- 407k
27
votes
Why are electrolytic capacitors still in production?
Your average Al electrolytic has a wonderful ESR-capacitance product in order to double as a snubber against nasty ringing at the MHz ballpark. This is cool because such ringing can easily appear due ...
- 22.5k
24
votes
Accepted
What is the purpose of an electrolytic capacitor in this small electronics project?
In any electronic circuit, especially digital ones like this, current drawn from the power supply will vary, as things like LEDs and logic gates switch on and off. Sudden changes like these can cause ...
- 39k
23
votes
Accepted
Is a minimum of 1000µF capacitance needed between an lm386's output and a speaker and if so why?
The capacitor referred in the video forms a high pass filter with the speaker (C-R filter).
Its frequency response is given by the following formula:
$$f_c = \frac1{2\pi \tau} = \frac1{2\pi RC}$$
...
- 7,954
23
votes
Accepted
Why do some SMD electrolytic capacitors have platforms?
Those capacitors are really made similarly to the cylindrical radial lead through-hole capacitors. Two connections come out through a rubber bung (in an aluminum case that is crimped at the bottom to ...
- 407k
23
votes
Accepted
Which manufacturer's logo is this?
Which manufacturer's logo is this?
Nichicon (or fakes): -
Here is the actual part (UCM series marked as CM): -
- 465k
23
votes
Using capacitors as a battery back-up
Introduction
I'm not going to touch on supercapacitors. If you can live with electrolytic capacitors, there's a trick: their low voltage energy density is underwhelming. And, to extract most energy ...
18
votes
Accepted
Storage of electrolytic capacitors - how long?
The main thing that degrades is the aluminum oxide dielectric layer on the surface of the aluminum foil. It's also possible that electrolyte (or at least its more volatile components) has leaked ...
- 175k
18
votes
Accepted
Can an electrolytic capacitor withstand 0.1 V reverse polarity?
"Can an electrolytic capacitor withstand 0.1V reverse polarity?"
If you query e.g. technical documents of a well known manufacturer like vishay:
Reverse Voltage UrevA reverse polarity of up ...
- 2,628
17
votes
Accepted
What does the term 'lifetime' mean for electrolytic capacitors
The "lifetime" is the total time the capacitor can be in service while subjected to the maximum stresses specified in the datasheet, after which the manufacturer no longer promises anything about the ...
- 314k
17
votes
Accepted
What is the "CV" unit for leakage current in a capacitor datasheet?
The leakage spec- in this case 0.01CV (or 3\$\mu\$A) is the product of rated voltage and rated capacitance, not applied voltage. The 3\$\mu\$A, of course, means "whichever is higher" (aka "worse"). ...
- 407k
16
votes
What is the purpose of an electrolytic capacitor in this small electronics project?
Nothing wrong with using those values. Maybe they had them around . Much larger and the capacitors rated for adequate voltage will get physically relatively large, but for 100-220uF or less they're ...
- 407k
14
votes
Accepted
Desoldering a through hole capacitor with weird terminals
Nevermind, it was just some sort of rivet inside the hole; I was assuming it was all a single piece since it didn't want to fully desolder. I just needed to up the desolder gun's temp to get it to ...
- 467
13
votes
Accepted
Why should care be taken while closing a capacitive circuit?
In theory when an empty capacitor is connected to a ideal voltage source, infinite current flows until capacitor is charged to the supplied voltage. Basically same thing when disconnecting a powered ...
- 159k
13
votes
Why are some capacitors bent on old boards?
More stress is placed on the leads if there is no space between the part and the PCB. Electrolytics are more fragile than some parts because of the semi-liquid electrolyte, which can leak if there is ...
- 4,667
12
votes
Accepted
How can I determine the current rating of a capacitor?
How can i know current rating of a capacitor?
From the datasheet.
Most capacitors don't actually have a "current" rating, since that doesn't make much sense. You can't put a sustained ...
- 314k
12
votes
Accepted
What do "cycles" in a capacitor mean?
It's your mains frequency (cycles per second). And MFD means microfarads, which you probably know already. You won't find a spec like that on the capacitor datasheet.
That's really, really old. 25Hz ...
- 407k
12
votes
How to Measure Very Large Capacitance e.g. Super/Ultra Capacitors
From the images of the cell in test setup photo they appear to be similar to the Maxwell DuraBlue line of Ultracapacitors. See this datasheet for more information.
The Maxwell application note 1007239,...
- 1,379
12
votes
Accepted
Maximal operational pressure of tantalum and electrolytic capacitors
This is said with significant caveats, but the only electrolytic capacitor options for a pressurized environment are ones with a solid electrolyte, so solid tantalum, tantalum polymer, or aluminum ...
- 29k
12
votes
Accepted
Do electrolytic capacitors lose lifetime during soldering in reflow oven?
Yes, it does degrade, but the capacitor specifications such as lifetime are given when the specific and allowable soldering conditions taken already into account, as you can't really use a capacitor ...
- 159k
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