component's value - Page 1
Forum section: electronics / beginners

author: alamwte
author_rank: Regular Contributor
timestamp: March 14, 2021, 10:24:40 am
content: Hello,I have 2 component that I have not seen before.Would you tell me what are they?And how can I measure their value?

author: mikerj
author_rank: Super Contributor
timestamp: March 14, 2021, 11:26:46 am
content: The top one looks like afeedthrough capacitorfor decoupling, typically the centre terminations would be grounded and the signal input and output connect to the outer terminations. They offer very low inductance compared to conventional two terminal SMD parts. To measure capacitance connect your LCR meter from one outer termination to one of the inner terminations.The lower part is an SMD inductor. Again you'd use an LCR meter to measure it's inductance and series resistance, but you may also need to know it's rated DC current which is more complex to measure unless your LCR meter provides this facility.

author: alamwte
author_rank: Regular Contributor
timestamp: March 15, 2021, 06:19:52 am
content: Got itThank you very much

author: Siwastaja
author_rank: Super Contributor
timestamp: March 15, 2021, 06:29:04 am
content: Also note real-world components don't have such a thing as "value"; especially not capacitors or inductors.Component "value" is such a simplification that applies to ideal components in classroom.Hence, measuring "value" is not often very helpful. If you need replacement, you need to know all the features of the part; datasheets are full of parameters and curve sets that describe the part!

author: alamwte
author_rank: Regular Contributor
timestamp: March 15, 2021, 09:56:51 am
content: Quote from: Siwastaja on March 15, 2021, 06:29:04 amI dont have its datasheet. I have found it on a board.Quote from: mikerj on March 14, 2021, 11:26:46 amI have a question. If it is a capacitor , why 2 outer terminals are connected together when I test it with buzzer test?

author: Ice-Tea
author_rank: Super Contributor
timestamp: March 15, 2021, 10:29:13 am
content: Did you follow the provided link? Should be clear why terminals are connected...

author: alamwte
author_rank: Regular Contributor
timestamp: March 15, 2021, 10:33:49 am
content: Quote from: Ice-Tea on March 15, 2021, 10:29:13 amOK, Sorry

author: archil
author_rank: Contributor
timestamp: March 16, 2021, 08:14:22 am
content: I have that components not seen before.

author: mvs
author_rank: Frequent Contributor
timestamp: March 16, 2021, 12:12:40 pm
content: Quote from: archil on March 16, 2021, 08:14:22 amFeedthru smd caps are not so widely used components in mass production circuits. Small caps (like 0402) are much cheaper and can be used for the same task in most cases.Wirewound chip inductors are actually quite common.

author: kimlanbu
author_rank: Newbie
timestamp: March 16, 2021, 01:36:44 pm
content: if you can't find anything you can choose 100nf as replacement. But obtaining a schematic and finding the exact value would be best.

author: Siwastaja
author_rank: Super Contributor
timestamp: March 16, 2021, 01:50:28 pm
content: Quote from: alamwte on March 15, 2021, 09:56:51 amYes, and that's exactly my point. For successful replacement, you need to:1) know what the component was. Not "value"; but a part number, so you can get the datasheet2) know why it failed (or why you need to replace it), so that you can finally understand,3) what kind of specifications the new component needs, so you can choose it properly

author: alamwte
author_rank: Regular Contributor
timestamp: March 16, 2021, 03:46:49 pm
content: Quote from: Siwastaja on March 16, 2021, 01:50:28 pmGreat guides, thank you

author: wraper
author_rank: Unknown
timestamp: March 16, 2021, 03:52:22 pm
content: First part may also be X2Y capacitor.

author: bobbydazzler
author_rank: Regular Contributor
timestamp: March 17, 2021, 08:47:55 pm
content: Quote from: alamwte on March 14, 2021, 10:24:40 amWhat board did you pull these components from? Apparently the twin capacitors can filter noise in the ghz range which is interesting.

author: TimFox
author_rank: Super Contributor
timestamp: March 17, 2021, 09:20:44 pm
content: The original form of feed-thru capacitors was designed to go through a hole in a metal panel. The threaded or solder-in mounting section corresponds to the outer terminals in the surface-mount device, and there is a center conductor (with different terminations depending on model) that corresponds to the end terminals. I was surprised when I first saw the symbol on a modern design, since I associated the symbol with the original hole-mount device. There were also button-mount standoff capacitors, with the capacitor between a center terminal and the circular flange, that were used to obtain very low self-inductance. Feed-through capacitors (and fancier filters) in the original form are still popular as inserts into connectors (in place of plain pins) for EMI reasons.

author: alamwte
author_rank: Regular Contributor
timestamp: March 18, 2021, 06:16:57 am
content: Quote from: TimFox on March 17, 2021, 09:20:44 pmOK, Thanks

author: Siwastaja
author_rank: Super Contributor
timestamp: March 18, 2021, 07:13:57 am
content: SMD feedthrough and X2Y caps are both a bit niche, though. The manufacturers claim significant benefits like they are the best thing since sliced bread, but they are comparing to purposely bad reference. With proper layout and properly placed vias, you can getveryclose with standard 0402 parts which have the obvious advantage of not having to buy special parts.Of course, sometimes even a small advantage matters.