caps in series?

[jorgenkjellgren]

When I need to add two caps together to get a certain value, do I just take one leg on each cap and twist them together? Do I need to solder that "twist". I this caps i series or is it paralel?
I have seen a pic of this somewhere on a DIY site but I couldn´t find it now.

Thanks, Jörgen

[bancika]

yeah, that's the way. keep in mind that when you connect them in series resulting value is c1*c2/c1+c2, unlike resistors serial...
you should solder connection

[Alex C]

When I need to add two caps together to get a certain value, do I just take one leg on each cap and twist them together? Do I need to solder that "twist". I this caps i series or is it paralel?

When combining capacitors in parallel (or resistors in series), it's easy; the values of the individual components are added.
When combining capacitors in series (or resistors in parallel), it's different.


When combining caps in series, as long as they're not polarized, you can do as you say, just take one lead on each cap and twist 'em together.  Soldering the twisted joint will ensure electrical continuity, which is a good thing.  I usually solder the "twist" fairly close to the bodies of the caps (but not too close), then snip off the excess twisted leads.  This "combined lead" made up of the one lead from each cap will not connect to anything; use the remaining lead on each cap and connect as you would a single cap of the desired value.

When combining caps in parallel, (again, as long as they're not polarized), twist and solder a lead on one cap to a lead on the other.  While they need not be physically parallel, it's often easiest to connect them when they are lined up in this way (so in this case, line them up next to each other pointing the same direction, and twist/solder together the two leads on one end).  Then twist and solder the other lead on the first cap to the other lead on the second (the two leads on the other end).  Now each of these "combined" leads will be connected as a single lead.

A handy thing to keep in mind when combining caps in series is that connecting two caps of the same value in series will result in a total capacitance equal to one half the original value.  (This is also true for two resistors of the same value connected in parallel- total resistance is one half the original resistance of each one.)

[Andre]

Another reason for using caps in series is, when you need a rather large nonpolar cap, let's say 4.7 uF, which is hardly available.
If you take 2 10 uF polarized caps and connect the minus leads, the result is a 5 uF nonpolar cap.

[jorgenkjellgren]

Great! Thanks guys!
Really helpful stuff.

Jörgen

[aron]

Yep it's in the FAQ re: series and parallel: