Stiffening Capacitor Values?

ok im lookin at a cap and i have a question. i seen two of them that say it has 120,000 MFD and another 500,000uf what does that mean and how does it compare to 1 Farad and .5 farad and so on let eme know thanks

 1,000,000 equals 1 farid, 120,000 uf is .12 farid, the 500,00 is .5 (1/2) farid

500,000 uf = .5 Farads, 120,000 = .12 Farads, don't let the big numbers confuse you. The key things to remember about purchasing a stiffening capacitor is to ensure the unit has a low ESR & ESL rating... And that if you are given the choice in selecting a 16 volt, or a 20 volt capacitor assuming they both had the same price. You would purchase the capacitor rated at 20 volts and with the lower ESR & ESL specifications... If you require me to explain the meaning of ESR & ESL I will do so. Regards EVIL Teken . . .

yeah can u just tell me waht it means and explain maybe give some examples thanks

Simply put, a capacitor stores electrical energy. The uf and MFD is micro farad. u or M is 10 ^ -6 or .0001. The basic unit of capacitance is the farad(a very large value). To explain a Farad, put in layman terms, it means if one ampere of current flows when the applied voltage changes at a rate of one volt per second, you have one farad of capacitance. The bigger the number the more electrical energy it can store. The 1 farad capacitor can store more energy than the 1/2 farad capacitor. Teken has to enlighten me on what ESR and ESL means. MEH66

"Car Performance and Mobile Electronic Enthusiats"

meh66 wrote: Teken has to enlighten me on what ESR and ESL means.

ESR is the (equivalent series resistance) of a capacitor. An ideal capacitor would have only capacitance, but this is not the case. All conductors have resistance and this includes a capacitor, there are multiple conductors like the wire leads, the foil, and the electrolyte within the unit which contribute to the resistance within the unit. The resistance of all of the conductors contribute to the capacitor's internal series resistance. This is the same as having a resistor in series with an ideal capacitor. Capacitors with high ESR will have less ability to pass current from its plates, to the external circuit such as the amplifiers in the case of stiffening capacitors in car audio environment. ESL is the (equivalent series inductance) of a capacitor. Since most electrolytic capacitors are basically a large coil of flat wire, it will have even more inductance than it would have if it were flat. This inductance, along with the small amount of inductance from the wire leads, will make up the ESL of the capacitor. The ESL is essentially the same as having an inductor in series with an ideal capacitor. Regards EVIL Teken . . .

meh66 wrote: Simply put, a capacitor stores electrical energy. The uf and MFD is micro farad. u or M is 10 ^ -6 or .0001.

From an engineering standpoint, I hate seeing manufacturers use "MFD" for "microfarad".  The metric abreviation "M" stands for "mega", which is a *million* of something, not a millionth of something.  The only appropriate prefix for "micro" is µ.  This represents .000001 of something (note five zeros to the right of the decimal point, not three)

Scott Gardner