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# How can I make a 225k 400v capacitor?

Hey I have a circuit that need 225k 400v capacitor but in my area that product is not available. So can any one tell me how I make a 225k 400v capacitor with some capacitors in parallel or in series? Tell the values of other capacitor that can make 225k 400v in serise or parallel.

## Discussions

Some parts of my answer will refer to the Wikipedia article titled "Capacitor", so I'll start with the link to that, here:

https://en.wikipedia.org/wiki/Capacitor

First thing: 225K is secret voodoo code. It actually stands for:

22*(10^5)*(10^-12 F) = 2.2*10^-6 F = 2.2 microfarad

and it would be helpful if you talk about, think about, your capacitors in honest units (like farads, microfarads, nanofarads, etc.) instead of secret voodoo markings. The section of the Wiki article which explains this is titled "Capacitor markings", here:

https://en.wikipedia.org/wiki/Capacitor#Capacitor_...

The next part of the problem is there is an infinite (or very large depending on the constraints) number of ways to build a network of capacitors into one with a specific capacitance you want; i.e. 2.2. microfarad, this is much like asking the question of how to make change for a dollar using coins of smaller value.

Four quarters will work: 25+25+25+25 = 100

So will three quarters, plus two dimes, plus one nickel: 25+25+25+10+10+5 = 100

Similarly, two 1.0 uF, plus two 0.1 uF capacitors, all in paralllel, will give a total capacitance of 1.0 uF + 1.0 uF + 0.1 uF + 0.1 uF = 2.2 uF

Or you could use twenty-two 0.1 uF capacitors, all in parallel,

0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1 = 2.2

The section of the Wiki article that explains parallel, and series networks of capacitors, is under "Theory of operation: Networks" here:

https://en.wikipedia.org/wiki/Capacitor#Networks

In practice I think you will have better luck building your big capacitor as a parallel combination of smaller capacitors. The reason why is because components in parallel all share the same voltage, so it is easy to calculate the voltage across each individual capacitor, because they all share the same voltage.

In contrast, for a network of capacitors in series, all larger than the capacitance of the whole network, the voltages across the individual capacitors are not all the same, and not as easy to predict.

Final note. Salespeople care about exact numbers, like $2.20, but for electronic circuits, approximate values will often work. For example, two 1.0 uF (secret voodoo code: 105) capacitors, in parallel, might work in place of one 2.2 uF capacitor (secret voodoo code: 105), even though the math is not exact:

1.0 + 1.0 = 2.0 != 2.2

What is a 225k capacitor? Capacitors are rated in Farad (F).

225K means 22*(10^5)*(10^-12 F) = 2.2*10^-6 F = 2.2 microfarad. The "K" indicates a 10% tolerance.

https://en.wikipedia.org/wiki/Capacitor#Capacitor_...

That looks like like total gibberish to me... :)

C'mon. We've been over this like a zillion times:

"*" means multiplication, e.g. 2*3 = 6

"x^y" means x raised to the power of y, e.g. 2^3=8, 10^3=1000

Parentheses, "(" , and ,")", are just some grouping operators. You do the math in the innermost groupied things first.

As for the capacitor marking voodoo code, it is just a variation of the same voodoo color code for resistors.

https://en.wikipedia.org/wiki/Electronic_color_cod...

The first two digits are just a decimal number.

The third digit is a power of 10.

Thus 225, in secret voodoo code, means 22*10^5, in words:

"twenty two times ten to the fiveth"

"twenty two times ten to the fifth"?

Well, I might not know how to spell it, but I know what it means.

For capacitors, the base unit is one picofarad (10^-12 F), so 22*10^5 multiplied by 10^-12 F is (22*10^5)*(10^-12 F) = 2.2*10-6 F

I'm pretty sure there was a department-wide memo on all this. I mean I can't help you if don't read your emails.

;-)

Fish paper and tinfoil, then layer until you have a capacitor the size you want.

Otherwise get 400 volt capacitors and connect them in parallel until you get the capacitance you want.

Or you can connect them in series to get the voltage you want, then connect the strings in parallel to get the capacitance you want.

Last take 4 1000 mF 100 volt capacitors and connect them in series to give you 225 mF 400 volt capacitor.

Of course that will only work if you are meaning 225 mF when you say 225 k.

Why not just buy them:

http://www.alibaba.com/showroom/original-new-capacitor-225k-400v.html