Replacing low value electrolytics with ceramic?

**Pentium4** · 12-13-2021, 02:23 AM

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 0.47µF 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.

**stj** · 12-13-2021, 06:04 AM

most ceramics are 60% tolerance.
i use polyester or polypropylene for 1uf and under.

**Per Hansson** · 12-13-2021, 11:18 AM

Ceramic capacitors capacitance are also voltage dependent.
So the general answer to this question would be no, you can't.

**PeteS in CA** · 12-13-2021, 01:48 PM

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.

**Pentium4** · 12-13-2021, 02:52 PM

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.

**PeteS in CA** · 12-14-2021, 03:03 PM

Ack! COG, not "CGO".

**eccerr0r** · 12-14-2021, 03:09 PM

but it is NP0?

**PeteS in CA** · 12-15-2021, 01:53 PM

"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).

**eccerr0r** · 12-15-2021, 02:54 PM

oh I was jusr being silly with O's and 0's, you know my username...

**PeteS in CA** · 12-16-2021, 01:26 PM

Quote:

Originally Posted by eccerr0r

oh I was jusr being silly with O's and 0's, you know my username...

OOOOOOooooooooK

**Pentium4** · 12-15-2021, 08:35 PM

I needed to order parts for something else so I just ordered some 0.47µF 50V nichicon UPW

**eccerr0r** · 12-16-2021, 02:02 PM

000000k it is

**TheLaw** · 12-16-2021, 04:02 PM

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.

**Pentium4** · 12-16-2021, 06:39 PM

Thanks for the link, that's a pretty useful tool

12-13-2021, 02:23 AM	#1
Pentium4 CapXon Be Gone Join Date: Sep 2011 City & State: Idaho My Country: USA Line Voltage: 120VAC 60Hz I'm a: Hardcore Geek Posts: 3,216	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 0.47µF 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.

12-13-2021, 06:04 AM	#2
stj Great Sage 齊天大聖 Join Date: Dec 2009 City & State: Europe My Country: some shithole run by Israeli agents I'm a: Professional Tech Posts: 26,681	Re: Replacing low value electrolytics with ceramic? most ceramics are 60% tolerance. i use polyester or polypropylene for 1uf and under.

12-13-2021, 11:18 AM	#3
Per Hansson Super Moderator Join Date: Jul 2005 City & State: ---- My Country: Sweden Line Voltage: 230v 50Hz I'm a: Knowledge Seeker Posts: 5,138	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."

12-13-2021, 01:48 PM	#4
PeteS in CA Badcaps Veteran 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: 3,387	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

12-13-2021, 02:52 PM	#5
Pentium4 CapXon Be Gone Join Date: Sep 2011 City & State: Idaho My Country: USA Line Voltage: 120VAC 60Hz I'm a: Hardcore Geek Posts: 3,216	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.

12-14-2021, 03:03 PM	#6
PeteS in CA Badcaps Veteran 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: 3,387	Re: Replacing low value electrolytics with ceramic? Ack! COG, not "CGO".

12-14-2021, 03:09 PM	#7
eccerr0r Solder Sloth Join Date: Nov 2012 City & State: CO My Country: USA Line Voltage: 120VAC 60Hz I'm a: Hobbyist Tech Posts: 7,165	Re: Replacing low value electrolytics with ceramic? but it is NP0?

12-15-2021, 01:53 PM	#8
PeteS in CA Badcaps Veteran 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: 3,387	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).

12-15-2021, 02:54 PM	#9
eccerr0r Solder Sloth Join Date: Nov 2012 City & State: CO My Country: USA Line Voltage: 120VAC 60Hz I'm a: Hobbyist Tech Posts: 7,165	Re: Replacing low value electrolytics with ceramic? oh I was jusr being silly with O's and 0's, you know my username...

12-15-2021, 08:35 PM	#11
Pentium4 CapXon Be Gone Join Date: Sep 2011 City & State: Idaho My Country: USA Line Voltage: 120VAC 60Hz I'm a: Hardcore Geek Posts: 3,216	Re: Replacing low value electrolytics with ceramic? I needed to order parts for something else so I just ordered some 0.47µF 50V nichicon UPW

12-16-2021, 02:02 PM	#12
eccerr0r Solder Sloth Join Date: Nov 2012 City & State: CO My Country: USA Line Voltage: 120VAC 60Hz I'm a: Hobbyist Tech Posts: 7,165	Re: Replacing low value electrolytics with ceramic? 000000k it is

12-16-2021, 04:02 PM	#13
TheLaw Badcaps Veteran Join Date: Jan 2011 City & State: New Jersey Posts: 449	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.

12-16-2021, 06:39 PM	#14
Pentium4 CapXon Be Gone Join Date: Sep 2011 City & State: Idaho My Country: USA Line Voltage: 120VAC 60Hz I'm a: Hardcore Geek Posts: 3,216	Re: Replacing low value electrolytics with ceramic? Thanks for the link, that's a pretty useful tool

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