Title: the 1 uF caps
Post by: sm0nor on 11. February 2018, 20:11:22
Hi, I'm wondering about these...
The BOM says COG/NPO types. But the suggested replacement is X7R type.
I think this is wrong, 1uF in COG, ceramic. Does it exist?
X7R type I can source locally but not COG.
/Ulf
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Title: Re:the 1 uF caps
Post by: SP9BSL on 12. February 2018, 11:30:00
Hi Ulf,
yes, THIS IS WRONG. There is nothing more than 100..220 nF in C0G/NP0 dielectric material and with larger than this size of package. Big manufacturers like TDK/SAMSUNG/YAGEO do not provide more than I wrote. The ones in Reichelt are very uncertain. If you look to the datasheet (let's call it datasheet) when you see at the larger values the change one letter inside the code from N to X (X7R?) and there is drop of accuracy from 5% to 10%. And to be more unsure in this "datasheet" you can find 10u ;D
Here is the data, you can look inside and make your opinion about RND:
http://cdn-reichelt.de/documents/datenblatt/B300/RND_1374311_CAP_0603_NP0_ENG_TDS.pdf |
Title: Re:the 1 uF caps
Post by: peter_77 on 12. February 2018, 13:52:09
Reichelt is Y5V, X5R or X7R:
https://www.reichelt.de/Vielschicht-SMD-G0805/2/index.html?ACTION=2&LA=2&GROUPID=8048;SID=97WcpydawQAT8AAEoiqGc349c8c9e0ab0cf5463daa55717381326 (https://www.reichelt.de/Vielschicht-SMD-G0805/2/index.html?ACTION=2&LA=2&GROUPID=8048;SID=97WcpydawQAT8AAEoiqGc349c8c9e0ab0cf5463daa55717381326) |
Title: Re:the 1 uF caps
Post by: sm0nor on 12. February 2018, 15:10:30
Title: Re:the 1 uF caps
Post by: AC9QP on 13. February 2018, 04:00:34
| You can get C0G 1uF in 0805 but they're not standard stock parts and I'm not sure about 0603. Really we do want C0G in the audio/baseband path as the microphonics and voltage coefficient of the X7R caps will degrade intermodulation performance by a few dB. In a future revision those caps should probably have bigger footprints so they can have film or available C0G caps which are much more linear for high dynamic range signal paths like this. |
Title: Re:the 1 uF caps
Post by: SP9BSL on 13. February 2018, 09:36:55
| Please point me at reliable datasheet and shop/seller where I can buy 1uF C0G/NPO. I'm very interested in this topic. |
Title: Re:the 1 uF caps
Post by: sm0nor on 13. February 2018, 10:25:04
Are the 1206's supplied in the kit COG types? I know the BOM says so, but can one identify that from the component itself?
/Ulf |
Title: Re:the 1 uF caps
Post by: AC9QP on 14. February 2018, 22:15:18
| I had one I thought was, but it turns out Mouser just had the wrong dielectric listed (be sure to check your datasheets). The next closest I can find is 470nF from Kemet in big packages (2220). Film caps are probably the best solution here. They're also big but not unobtanium. |
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