Condensateurs

[Look165]

Je sais que la question est limite "components".

Voilà mon problème :

Si je mets 2 condensateurs chimiques de tension et valeur diffĂŠrentes en
parallèle, est-ce que ça pose un problème , sachant que c'est la plus
basse qui prĂŠvaut ?

Merci

 

[Look165]

la plus basse tension, je voulais dire.

Look165 a ĂŠcrit :

Je sais que la question est limite "components".

Voilà mon problème :

Si je mets 2 condensateurs chimiques de tension et valeur diffĂŠrentes en
parallèle, est-ce que ça pose un problème , sachant que c'est la plus
basse qui prĂŠvaut ?

Merci

 

[Tilmann Reh]

Look165 schrieb:

Je sais que la question est limite "components".

Voilà mon problème :

Si je mets 2 condensateurs chimiques de tension et valeur diffĂŠrentes en
parallèle, est-ce que ça pose un problème , sachant que c'est la plus
basse qui prĂŠvaut ?

I assume you'd get more answers here when asking in english...

However, if I understood your question correctly...:
Of course you may connect two different capacitors in parallel as long
as both are operated within their voltage range, i.e. the voltage must
not exceed the lowest voltage rating of these capacitors.

As an example: Connect two electrolytics of 100 ÂľF / 50 V and 470 ÂľF /
16 V in parallel, and you'll get a 570 ÂľF / 16 V capacitor.

Tilmann

 

[Look165]

Of course !

But what about the relibility ? and what about the repartition of the
currents since the ESR of each would be slightly different ?

Sorry for the writing, I'm French.

Tilmann Reh a ĂŠcrit :

Look165 schrieb:

Je sais que la question est limite "components".

Voilà mon problème :

Si je mets 2 condensateurs chimiques de tension et valeur diffĂŠrentes en
parallèle, est-ce que ça pose un problème , sachant que c'est la plus
basse qui prĂŠvaut ?

I assume you'd get more answers here when asking in english...

However, if I understood your question correctly...:
Of course you may connect two different capacitors in parallel as long
as both are operated within their voltage range, i.e. the voltage must
not exceed the lowest voltage rating of these capacitors.

As an example: Connect two electrolytics of 100 ÂľF / 50 V and 470 ÂľF /
16 V in parallel, and you'll get a 570 ÂľF / 16 V capacitor.

Tilmann

 

[Hans-Peter Diettrich]

Look165 schrieb:

Si je mets 2 condensateurs chimiques de tension et valeur diffĂŠrentes en
parallèle, est-ce que ça pose un problème , sachant que c'est la plus
basse qui prĂŠvaut ?

La plus basse tension, oui.

DoDi

 

[Hans-Peter Diettrich]

Look165 schrieb:

But what about the relibility ? and what about the repartition of the
currents since the ESR of each would be slightly different ?

Les courants individuÊls ne dÊpendent d'autres ÊlÊments *en parallèl*.

> Sorry for the writing, I'm French.

Sorry2, je suis Allemand.

DoDi

 

[Look165]

Merci de la rĂŠponse, mais c'est cĂ´tĂŠ ESR que je suis inquiet

Hans-Peter Diettrich a ĂŠcrit :

Look165 schrieb:

Si je mets 2 condensateurs chimiques de tension et valeur diffĂŠrentes
en parallèle, est-ce que ça pose un problème , sachant que c'est la
plus basse qui prĂŠvaut ?

La plus basse tension, oui.

DoDi

 

[Johann Klammer]

On 01/05/2016 11:00 AM, Look165 wrote:

Merci de la rĂŠponse, mais c'est cĂ´tĂŠ ESR que je suis inquiet

Hans-Peter Diettrich a ĂŠcrit :
Look165 schrieb:

Si je mets 2 condensateurs chimiques de tension et valeur diffĂŠrentes
en parallèle, est-ce que ça pose un problème , sachant que c'est la
plus basse qui prĂŠvaut ?

La plus basse tension, oui.

DoDi

It's quite common to use 'lytics and a small ceramic in parallel, as the
ceramic one will gobble up narrow spikes better because of it's lower
resistance. Impulse currents will be a bit higher there, I guess.

 

[Look165]

I know and I have used that ( 100uF // with 10nF ceram).

But here the goal is to match a value of capa with my "onboard" components !

I repeat that the problem I could face is with the resulting ESR.

My actual problem is to make 1200uF with 1000//220 of the same
manufacturer and of the same series (I know that 1200//220 don't really
make 1220 but a little less).

But the ESR will also be somehow in // , what will result ?
And if you want to combine this with the parasistic // resistor of the
capas...

Johann Klammer a ĂŠcrit :

On 01/05/2016 11:00 AM, Look165 wrote:
Merci de la rĂŠponse, mais c'est cĂ´tĂŠ ESR que je suis inquiet

Hans-Peter Diettrich a ĂŠcrit :
Look165 schrieb:

Si je mets 2 condensateurs chimiques de tension et valeur diffĂŠrentes
en parallèle, est-ce que ça pose un problème , sachant que c'est la
plus basse qui prĂŠvaut ?

La plus basse tension, oui.

DoDi

It's quite common to use 'lytics and a small ceramic in parallel, as the
ceramic one will gobble up narrow spikes better because of it's lower
resistance. Impulse currents will be a bit higher there, I guess.

 

[legg]

On Tue, 5 Jan 2016 13:19:52 +0100, Look165 <look165@numericable.fr>
wrote:

I know and I have used that ( 100uF // with 10nF ceram).

But here the goal is to match a value of capa with my "onboard" components !

I repeat that the problem I could face is with the resulting ESR.

My actual problem is to make 1200uF with 1000//220 of the same
manufacturer and of the same series (I know that 1200//220 don't really
make 1220 but a little less).

But the ESR will also be somehow in // , what will result ?
And if you want to combine this with the parasistic // resistor of the
capas...

You are aware that the tolerance of these parts is in the 20% range?

Providing that the circuit's ripple/dropout performance is not
objectionable, adding the 220uF part will be non-critical, if the esr
of the 1000uF replacement is similar to the original 1200uF part, and
their case sizes have similar surface area.

Failure mode of these parts, below 63V, is increasing ESR, evident by
increasing ripple and temperature. The 1000uF part will dominate.
Electrolytics of the same mfr series and voltage will normally share
current proportionally, if not influenced by layout or external heat
sources.

Given development in the cap industry, it is usually possible to
provide similar or superior substitution at the time of replacement.
If this is a new design, you should review the design requirements to
identify the dominant parameters. At 50/60hz, esr is seldom dominant.

RL