| | Resistors I got, Capacitors frustrate me... | | It is not that hard to understand: Capacitor act just like resistors for | AC. The higher the frequency, the more current can flow ... | The complex impedance is Z := 2*Pi*(-i)/f*C, where f is | frequency in Hertz, C is the capacity in Farad and i is the imaginary | ... This just means that the impedance (the | resistance, basically) approaches zero if the frequency approaches infinity. | | Best regards, | Jens
To avoid the arithmetic, think of the capacitors as little buckets. Apply a little voltage (pressure) and current (amps, milliamps, ...) flows into the bucket. If you applied DC, the bucket would just fill up, then eventually stop (given a constant voltage/pressure). Apply AC, and the pressure is continuously changing. The bucket fills up, then it dumps, when the voltage drops. Fills up in the other direction, and dumps again, according to how the applied voltage is moving. At low frequencies, the bucket fills up, and waits for a while, before the voltages shifts, and allows it to dump. At higher frequencies, the fill/dump cycle occurs more often, meaning more AC current will flow. So here's a visual analogy of the arithmetic above. The bucket analogy works, because capacitors will store charge (a quantity of electrons). In our logic circuits, we want those buckets real close to our chips. That way, when the chip needs a lot of juice right away, there it is. The closer the better. With modern chips, that's right at the power & gnd pins. The chip makers now put the power and gnd pins next to each other, and may have a section in their datasheet telling you what that chip needs ... capacitor-wise. Also, real capacitors you buy in the store are never like the 'ideal' capacitors seen in text books. That's why there are so many types. Aluminum electrolytics are the worse, but have high capacitance-to-volume density. Ceramics are the best commonly found, but aren't perfect. That 'i' is the imaginary operator. They use 'i' in math, and usually 'j' in engineering, but its the same thing (j = square root of -1). Its used so a value can be given as a phasor (both amplitude and phase, not the Star Trek thingy). Don't let the term 'imaginary' fool you. Its math-speak, like 'normal' (=perpendicular). The imaginary component is 90 degrees off of the 'real' component. But if you get your hands across an 'imaginary' 200V, it will bite you just the same as the 'real' 200V. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
