A little refresher please - Capacitors in parallel

McIntosh Man · 3rd March 2010, 02:36 AM

I need a confirmation about the rule that I learned in College too long ago.

When 2 capacitors of 25 uf - 100v are in a parrallel circuit the total capacitance for this circuit will be 12.5 uf at a mximum voltage of 100volts ?

When 2 capacitors of 25 uf - 100v are in a series circuit the total capacitance for this circuit will be 25 uf but maximum voltage of 200volts ?

Theses rules apply to Non-Polarized capacitors also ?

Please refresh my memory, thanks.

planet10 · 3rd March 2010, 03:06 AM

Capacitors in parallel sum. 2x25 = 50 uF, 100v in your case

capacitors in series Csum=1/(1/C1 + 1/C2) voltage the sum of the voltages of the caps (12.5 uF, 200V in your case).

dave

Speedskater · 3rd March 2010, 03:45 PM

Quote:

Originally Posted by planet10

capacitors in series Csum=1/(1/C1 + 1/C2) voltage the sum of the voltages of the caps (12.5 uF, 200V in your case).
dave

I'll give the 200 Volt rating a big maybe. Capacitors in series may not divide the voltages evenly. Often a high value resistor is connected across each cap. to help with the voltage division.

planet10 · 3rd March 2010, 04:47 PM

Quote:

Originally Posted by Speedskater

Often a high value resistor is connected across each cap. to help with the voltage division.

Always recommended.

dave

McIntosh Man · 3rd March 2010, 07:07 PM

Quote:

Originally Posted by Speedskater

I'll give the 200 Volt rating a big maybe. Capacitors in series may not divide the voltages evenly. Often a high value resistor is connected across each cap. to help with the voltage division.

When you say high value resistor what kind of value (in ohms) are we talking about ?

Also how many watt resistor do you recommend, 1/4 w, 1/8 w, 1/2 w, 1 watt, 2 watts ?

Speedskater · 4th March 2010, 03:09 PM

Quote:

Originally Posted by McIntosh Man

When you say high value resistor what kind of value (in ohms) are we talking about ?
Also how many watt resistor do you recommend, 1/4 w, 1/8 w, 1/2 w, 1 watt, 2 watts ?

I don't remember!
Probably someone in the "Tubes / Valves" sub-forum would know.

aud1out · 4th March 2010, 05:23 PM

Hope this is not off topic.

What happens to ripple current and ESR when you parallel / series?

AuroraB · 4th March 2010, 06:47 PM

1/2 W should be OK, - calculate the value up to max current without overloading the resistor......

3rd March 2010, 02:36 AM	#1
McIntosh Man diyAudio Member Join Date: Mar 2010 Location: Quebec, Canada	A little refresher please - Capacitors in parallel I need a confirmation about the rule that I learned in College too long ago. When 2 capacitors of 25 uf - 100v are in a parrallel circuit the total capacitance for this circuit will be 12.5 uf at a mximum voltage of 100volts ? When 2 capacitors of 25 uf - 100v are in a series circuit the total capacitance for this circuit will be 25 uf but maximum voltage of 200volts ? Theses rules apply to Non-Polarized capacitors also ? Please refresh my memory, thanks.

3rd March 2010, 03:06 AM	#2
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	Capacitors in parallel sum. 2x25 = 50 uF, 100v in your case capacitors in series Csum=1/(1/C1 + 1/C2) voltage the sum of the voltages of the caps (12.5 uF, 200V in your case). dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

4th March 2010, 05:23 PM	#7
aud1out diyAudio Member Join Date: Mar 2006 Location: Ontario	Ripple current and ESR Hope this is not off topic. What happens to ripple current and ESR when you parallel / series?

4th March 2010, 06:47 PM	#8
AuroraB diyAudio Member Join Date: May 2001 Location: Norway, -north of the moral circle..	1/2 W should be OK, - calculate the value up to max current without overloading the resistor...... __________________ While the Lie leapt from Bagdad to Constantinopel, the Truth was still looking for it's sandals!

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