Capacitors

[Stlouisian]

How do you make different MFD's out of capacitors? Are they like resistors where you hook them up in series they become the total of all the resistors together? Thanks for any help.

Ross

[sean]

Hi Ross,

Capacitors in parallel add. Capacitors in series are like resistors in parallel.
Ctotal = 1/(1/C1 + 1/C2 + ... + 1/Cx), or Ctotal = (C1*C2) / (C1+C2) if you only have 2 capacitors. So to recap , resistors and capacitors are opposites mathematically. Capacitors in series are like resistors in parallel, capacitors in parallel are like resistors in series.

[wa2ise]

In theory, series connected caps see lower voltages than the parallel case. However, any leakages in one or both caps can change the voltage that theory would predict. So I would not try to use a pair of say 1uF @ 200V caps in series across a 400V supply. In a pairing with caps of different values, the bigger capacitence will see lower voltage across it in theory.

I've used parallel sets of caps fairly often. In some applications, using smaller paralleled caps reduces AC currents thru any one cap, and improves reliability. This especially for the coupling cap for the horizontal portion of the deflection yoke. There ESR matters. A set of parallel ordinary caps will have lower ESR than one bigger ordinary cap.