Badcaps.net Forum
Go Back   Badcaps Forums > General Topics > General Capacitor Questions & Issues
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 12-13-2021, 02:23 AM   #1
Pentium4
CapXon Be Gone
 
Pentium4's Avatar
 
Join Date: Sep 2011
City & State: Idaho
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hardcore Geek
Posts: 3,216
Default Replacing low value electrolytics with ceramic?

So I disappeared from working on electronics for quite some time. I'm unboxing my ancient projects and want to resume some of them. Unfortunately, my knowledge is a little rusty.

I've always liked to do full recaps on power supplies. My cap supply isn't perfect and I do not have any more 0.47F 50V caps. I do have some ceramic caps with that value. Can they replace the lytic without issues? If I remember correctly, their max voltage drops rapidly after getting hot. Is that correct? If this isn't a good idea, I doubt the cap will cause any problems. It's by the main controller/exhaust so I doubt it will get hot or fail but I like to be thorough.
Pentium4 is offline   Reply With Quote
Old 12-13-2021, 06:04 AM   #2
stj
Great Sage 齊天大聖
 
stj's Avatar
 
Join Date: Dec 2009
City & State: Europe
My Country: some shithole run by Israeli agents
I'm a: Professional Tech
Posts: 26,678
Default Re: Replacing low value electrolytics with ceramic?

most ceramics are 60% tolerance.
i use polyester or polypropylene for 1uf and under.
stj is offline   Reply With Quote
Old 12-13-2021, 11:18 AM   #3
Per Hansson
Super Moderator
 
Per Hansson's Avatar
 
Join Date: Jul 2005
City & State: ----
My Country: Sweden
Line Voltage: 230v 50Hz
I'm a: Knowledge Seeker
Posts: 5,132
Default Re: Replacing low value electrolytics with ceramic?

Ceramic capacitors capacitance are also voltage dependent.
So the general answer to this question would be no, you can't.
__________________
"The one who says it cannot be done should never interrupt the one who is doing it."
Per Hansson is offline   Reply With Quote
Old 12-13-2021, 01:48 PM   #4
PeteS in CA
Badcaps Veteran
 
PeteS in CA's Avatar
 
Join Date: Aug 2005
City & State: San Jose, CA
My Country: USA, Unsure of Planet
Line Voltage: 120VAC, 60Hz & 115VAC, 400Hz
I'm a: Professional Tech
Posts: 3,385
Default Re: Replacing low value electrolytics with ceramic?

If you can get same value/voltage CGO ceramics, you won't have to worry about the temperature or voltage coefficients. If X7R, then the combined tolerance will be, IIRC, +/-20%. Z5U and Y5V are crap, IMO.

That said, the impedance characteristic will be very different from lytics.
__________________
PeteS in CA

Power Supplies should be boring: No loud noises, no bright flashes, and no bad smells.
****************************
To kill personal responsibility, initiative or success, punish it by taxing it. To encourage irresponsibility, improvidence, dependence and failure, reward it by subsidizing it.
****************************
Anti-Covid-Vaxxer pig crap claim/prediction, Doctor: Heart Failure from mRNA Jabs "Will Kill Most People" | Principia Scientific Intl. ; Dr. Geert Vanden Bossche Warns COVID-19 Jab Injuries and Deaths Will Soon "Collapse Our Health System" (VIDEO) ; Fully Vaxxed May 2021; Since that time I've done 7 5Ks, 1 8K, 8 10Ks, and 4 half marathons
PeteS in CA is offline   Reply With Quote
Old 12-13-2021, 02:52 PM   #5
Pentium4
CapXon Be Gone
 
Pentium4's Avatar
 
Join Date: Sep 2011
City & State: Idaho
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hardcore Geek
Posts: 3,216
Default Re: Replacing low value electrolytics with ceramic?

Thanks for the replies. I couldn't find anything suitable in my parts bin. I think I will just leave the cap where it is. All the other higher value caps will be replaced which should be good enough.
Pentium4 is offline   Reply With Quote
Old 12-14-2021, 03:03 PM   #6
PeteS in CA
Badcaps Veteran
 
PeteS in CA's Avatar
 
Join Date: Aug 2005
City & State: San Jose, CA
My Country: USA, Unsure of Planet
Line Voltage: 120VAC, 60Hz & 115VAC, 400Hz
I'm a: Professional Tech
Posts: 3,385
Default Re: Replacing low value electrolytics with ceramic?

Ack! COG, not "CGO".
PeteS in CA is offline   Reply With Quote
Old 12-14-2021, 03:09 PM   #7
eccerr0r
Solder Sloth
 
eccerr0r's Avatar
 
Join Date: Nov 2012
City & State: CO
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist Tech
Posts: 7,163
Default Re: Replacing low value electrolytics with ceramic?

but it is NP0?
eccerr0r is offline   Reply With Quote
Old 12-15-2021, 01:53 PM   #8
PeteS in CA
Badcaps Veteran
 
PeteS in CA's Avatar
 
Join Date: Aug 2005
City & State: San Jose, CA
My Country: USA, Unsure of Planet
Line Voltage: 120VAC, 60Hz & 115VAC, 400Hz
I'm a: Professional Tech
Posts: 3,385
Default Re: Replacing low value electrolytics with ceramic?

"COG" and "NPO" are the same thing, probably nomenclature going back more decades than I do (I think I saw the terms used in late 1950s vintage TV technician magazines).
PeteS in CA is offline   Reply With Quote
Old 12-15-2021, 02:54 PM   #9
eccerr0r
Solder Sloth
 
eccerr0r's Avatar
 
Join Date: Nov 2012
City & State: CO
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist Tech
Posts: 7,163
Default Re: Replacing low value electrolytics with ceramic?

oh I was jusr being silly with O's and 0's, you know my username...
eccerr0r is offline   Reply With Quote
Old 12-15-2021, 08:35 PM   #10
Pentium4
CapXon Be Gone
 
Pentium4's Avatar
 
Join Date: Sep 2011
City & State: Idaho
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hardcore Geek
Posts: 3,216
Default Re: Replacing low value electrolytics with ceramic?

I needed to order parts for something else so I just ordered some 0.47F 50V nichicon UPW
Pentium4 is offline   Reply With Quote
Old 12-16-2021, 01:26 PM   #11
PeteS in CA
Badcaps Veteran
 
PeteS in CA's Avatar
 
Join Date: Aug 2005
City & State: San Jose, CA
My Country: USA, Unsure of Planet
Line Voltage: 120VAC, 60Hz & 115VAC, 400Hz
I'm a: Professional Tech
Posts: 3,385
Default Re: Replacing low value electrolytics with ceramic?

Quote:
Originally Posted by eccerr0r View Post
oh I was jusr being silly with O's and 0's, you know my username...
OOOOOOooooooooK
PeteS in CA is offline   Reply With Quote
Old 12-16-2021, 02:02 PM   #12
eccerr0r
Solder Sloth
 
eccerr0r's Avatar
 
Join Date: Nov 2012
City & State: CO
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hobbyist Tech
Posts: 7,163
Default Re: Replacing low value electrolytics with ceramic?

000000k it is
eccerr0r is offline   Reply With Quote
Old 12-16-2021, 04:02 PM   #13
TheLaw
Badcaps Veteran
 
Join Date: Jan 2011
City & State: New Jersey
Posts: 449
Default Re: Replacing low value electrolytics with ceramic?

If you want to visualize how capacitance drops with applied DC bias voltage, you can check out Kemet's KSIM web app:

https://ksim3.kemet.com/capacitor-simulation

The limitation is fundamentally package size, and more directly, the physical amount of dielectric material contained. Since Class II ceramics are ferroelectric, they "saturate" similar to how an inductor's core might. More material means it saturates less under the same DC bias conditions.

Beware of "too good to be true" capacitance values in tiny packages. Sure you can get a 1.0uF/25V 0603 capacitor, but you better not use it above 5V, if you really need a 1.0uF capacitor.
TheLaw is offline   Reply With Quote
Old 12-16-2021, 06:39 PM   #14
Pentium4
CapXon Be Gone
 
Pentium4's Avatar
 
Join Date: Sep 2011
City & State: Idaho
My Country: USA
Line Voltage: 120VAC 60Hz
I'm a: Hardcore Geek
Posts: 3,216
Default Re: Replacing low value electrolytics with ceramic?

Thanks for the link, that's a pretty useful tool
Pentium4 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2022
Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 03:06 PM.
Did you find this forum helpful?