Calculate Capacitors in Series?

[carboncomp]

Hello guys.

I get C1XC2 over C1+C2  

But, I am having some trouble getting my head around how to calculate equivalent capacitance of more then two caps in series (My maths skills are terrible, so please bear with me!)

So, I look on-line and the formula is:
(1/C TOTAL) = (1/C1) + (1/C2) + (1/C3)

So, lets say we got 3 x 10uF caps in Series, I'm doing it like this:

(1/C TOTAL) = (1/10uF) + (1/10uF) + (1/10uF) =

(1/C TOTAL) = (0.1uF) + (0.1uF) + (0.1uF) = 0.3uf

But according to a Capacitors in Series Calculator it = 3.33uf

Where am I going wrong?

[GGBB]

You left out the last step to invert:

1 / C TOTAL = 0.3uf

therefore

C TOTAL = 1 / 0.3uf = 3.3uf

[carboncomp]

You left out the last step to invert:

1 / C TOTAL = 0.3uf

therefore

C TOTAL = 1 / 0.3uf = 3.3uf

Oh, the (1/C) at the beginning!

So, if I had 10uf 5uf and 50uf:

(1/10) + (1/5) + (1/50) =

(0.1) + (0.2) + (0.02) = 0.32

0.32/1 = 3.125uF 

[davent]

You left out the last step to invert:

1 / C TOTAL = 0.3uf

therefore

C TOTAL = 1 / 0.3uf = 3.3uf

Oh, the (1/C) at the beginning!

So, if I had 10uf 5uf and 50uf:

(1/10) + (1/5) + (1/50) =

(0.1) + (0.2) + (0.02) = 0.32

0.32/1 = 3.125uF  

Nope... be careful!

0.32÷1=0.32

1÷0.32=3.125

[ashcat_lt]

0.32/1 = 0.32 , but we know what you meant

It's the same as parallel resistors.  

(Hopefully) Interesting tidbits which can help verify your calculations:

You can use the simplified "2 component" equation recursively to get the same result.

The answer will never be greater than the smallest value.

The greater the difference in the values, the closer the answer will be to the smallest value.

The answer will never be less than if they were all the smallest value.  

The answer can't be any less than the smallest value divided by the number of components.

[carboncomp]

0.32/1 = 0.32 , but we know what you meant

just spotted I had that the wrong way round!

It's the same as parallel resistors.  

(Hopefully) Interesting tidbits which can help verify your calculations:

You can use the simplified "2 component" equation recursively to get the same result.

The answer will never be greater than the smallest value.

The greater the difference in the values, the closer the answer will be to the smallest value.

The answer will never be less than if they were all the smallest value.  

The answer can't be any less than the smallest value divided by the number of components.

Im going to be straight up with you, I don't understand the following sentence:

You can use the simplified "2 component" equation recursively to get the same result.

recursively!?!?!?   as in I can brake multiples down into groups of two and repeat the equation?

But the rest of the tips are very cool, and iv just writer them in my note pad!  

[Jdansti]

Hopefully your calculator has a 1/x function

Do all of your 1/C 's first, add them together, and then hit the 1/x button.

[slacker]

recursively.....

yeah exactly, break it down into groups of two and repeat.
If the caps are the same value it simplifies to value/number of caps.

[Maik]

Hi
Why not using this?
http://www.electronics2000.co.uk/

[Paul Marossy]

Hi
Why not using this?
http://www.electronics2000.co.uk/

I have that program. Very handy!

[ashcat_lt]

recursively.....

yeah exactly, break it down into groups of two and repeat.
If the caps are the same value it simplifies to value/number of caps.

Yeah, or do two, then that answer with the next value...

[wavley]

I keep a graphing calculator with me always whenever I'm going to be near electronics (it doesn't have to be graphing, but mine does metric prefixes so I can just plug things in as u, m, M... whathaveyou).  Like my old mentor said "it's just as important as your mulitimeter, you wouldn't work on electronics without your multimeter would you?"

That said, I almost never turn it on anymore because my phone is always in my pocket so it's closer and there are some really great apps that you only have to choose the formula and plug in your values.  Agilent's Engineering Calculator is great especially if you want smith charts (also Agilent uWave calculator is a great app for me considering my day job is mostly GHz) The Niranjan Kumar electronics apps are really great: there is one that does 555 Timer values, LED resistor values, LEDs in series, and Logic Gates and the other app does most of our common formulas for Ohm's law, series/parallel caps and resistors, color codes, voltage dividers, RC circuits... blah blah blah= It's really handy!

edit: Don't interpret this as me saying "Don't bother learning the math" because knowing why the math works helps you understand everything so much better.