Originally Posted by
Eclipse99RS
ouch...
Trying to follow this whole debate but its too late to think but I figure I might toss a couple things in.
1.Isn't it true that the discharge rate of a cap would have an effect on how long the cap holds a charge?
2.The discharge rate of a cap is theoryectically inversely proportional to the resistance. Or is the changes in resistance so small that they don't don't really matter and a cap appears to discharge almost instantaniously?
Feel free to correct me or add to it cause i'm pretty much just starting my electrical engineering degree and i'm trying to apply some of the things from my classes to cars. I understand how things go together and why, I'm trying to learn the actual math and science behind it.
First off, YEY EE!!! Are you going to USF? If so we might run into eachother in some classes.
now for the Qs
1. The discharge rate is directly related to its voltage. So more than 60% of a 1farad capacitor is useless as it will supply current below 9-10 volts. Thats why you will only get about a 1/4th of a second of usable power. But thats all you really need in the intended application.
2. Yes the higher the resistance the slower the capacitor discharge. Thats why the cap must be as close to with parallel connections (+12v AND ground) to the capacitor.
In the same spirit, if you examine the printed circuit board of an amplifier, the power supply conductors to the capacitors are always 300% to 500% larger than the rest of the conductors including the output leads! Also keep in mind that the ESR from the capacitor to the amplifier (even when including the conductors that connect the wires) will be several times less than the length of copper wire to the battery and its own connectors.