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can i use capacitors in paralel/serial like resistors? Answered

i know about resistors that when u use them in serial, the ohm values should be added to eachother and then you have the total resistance, or when in paralel, count it up and divide by the number of resistors (right)
what i want to know is, does this aply for capacitors as well? like when i use a 1.0 uF capacitor and a 0.1uF capacitor in series, i get 1.1uF
please note that the ones im planning to use are ceramic.
and if they weren't should i connect them like leds in serial? like positive of one cap to negative of the other?

Discussions

0
NachoMahma
NachoMahma

Best Answer 10 years ago




http://en.wikipedia.org/wiki/Series_and_parallel_circuits

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godofal
godofal

Answer 10 years ago

it looks to me that it is, but im not that sure, so, is it yes, or no?

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NachoMahma
NachoMahma

Answer 10 years ago

.  Look at the formula for series resistors. Now look at the formula for parallel capacitors.
.  Look at the formula for parallel resistors. Now look at the formula for series capacitors.
.  See a pattern?
.  Capacitors can be lethal. Hold off building whatever it is you are building until you understand capacitors and their hazards better.

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godofal
godofal

Answer 10 years ago

im building this
i thought i'd order a 1.1uF cap, but it seems like i didnt (cant find it anyway) and i do have a 1.0uF and a 0.1uF cap.

so, if i understand correctly, it works the same.

thnx.

0
NachoMahma
NachoMahma

Answer 10 years ago

.  OK. Now I see your problem.
1 .1 uf Capacitor - 272-135
This capacitor (C1) acts as a smoothing capacitor . It should be only a ceramic disk capacitor.
.  The preceding paragraph should be read:
1 each 0.1uF Capacitor ...
.  Even if it was 1.1uF, it's just a filtering cap, so 1.0uF would most likely be close enough.
0
godofal
godofal

Answer 10 years ago

lol, didnt even see that really.
anyway, im going to use just a single 0.1 uF ceramic cap, and thatl be the end of it (i hope)

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gmoon
gmoon

Answer 10 years ago

Have you looked at the schematic? It's clearly a 0.1uF and a 10uF cap.

The 0.1uF cap in that circuit is probably there to shunt away any high frequencies (to prevent oscillation and noise), and is usually referred to as a decoupling cap. The 10uF cap is the smoothing (reservoir, or filtering) cap.

Other than that +++++ for everything Nacho wrote. When even good production caps have a +/- 20% error, you'll never see something like 1.1uF specified on a schematic.

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NachoMahma
NachoMahma

Answer 10 years ago

.  It's not the same for capacitors and resistors - it's "backwards."
Parallel resistor and series capacitor networks use the same basic formula.
Series resistor and parallel capacitor networks use the same basic formula.

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steveastrouk
steveastrouk

10 years ago

Two things:
1.) It SAYS 1.1uF, it MEANS 1, 0.1 uF capacitor
2.) There is no need to be that specific with this capacitor. Its very very rare to need to select a capacitor with a very high precision.

Steve

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godofal
godofal

Answer 10 years ago

why are all the caps being sold from 0.1uF up to 0.1 pF (thought that was smaller, might be wrong)

so if its not accurate at 0.1 uF then how can it be accurate when its alot less?

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frollard
frollard

Answer 10 years ago

Units,

farads are HUGE, hence why the common units are
uF - microfarads, 1/1000 farad
pF picofarads, and 1/1,000,000 farad
nF nanofarads. 1/1,000,000,000 farad

its uncommon for a 1uF capacitor to be precise to the picofarads, because its an order of magnitude bigger.  It doesn't make sense to have a picofarad cap accurate to the nanofarads...again, its too big for that kind of precision.

It DOES make sense to have a picofarad cap precise to the tenth of a picofarad though - because when you need a specific value, being off by double or triple can cause problems.

As for adding them up - they do the exact opposite as resistors, since they do the opposite of what resistors do - acting sort-of like batteries that don't conduct when they're fully charged.  add them in series and you get inverse of sum of the inverses.  Add them in parallel and you add their values.

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NachoMahma
NachoMahma

Answer 10 years ago

steveastrouk said: Its very very rare to need to select a capacitor with a very high precision.
.  I would amend that to: Its very very rare to need to select a filtering capacitor with a very high precision.
.
.  When you get into timer, radio, AC, and other type circuits, "pretty close" may not be close enough.

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willywoozle
willywoozle

Answer 10 years ago

Yes, I was going to correct that.... thanks !

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godofal
godofal

Answer 10 years ago

il keep that in mind ;)