[mcguyver]

That article gives some basic intro into the use of capacitors. However there are some flaws in their reasoning for capacitor use that lend it to be a waste of time for an airsoft gun.

1) The motor used in an AEG is a universal motor (both AC and DC capable) that uses internal phase reversal via the commutator to achieve rotation. This will cause the DC output of the capacitor to also fluctuate, negating exactly half of it's potential.

2) The motor acts like an inductor (as the windings are basically inductors) and will exhibit the electrical characteristics of one. This means that during motor operation, the current going to the motor will lag it's voltage by a factor dependent upon the pure inductance of the windings and their resistance. This is a fixed value during motor load and a fixed value when the motor runs but is not under load. These values are different and may vary significantly.

Using the pure capacitance of a capacitor (as they effectively have zero resistance) to offset the motor inductance (known as "power factor correction") may lower the net current during motor load running, but may also increase current needs when discharging during motor running with no-load (half the time). You may in effect be taking the lagging current drawn by the motor and turn it into leading current drawn by the capacitor. So you gain nothing, except the added expense and effort of installing the capacitor in the first place.

Now we get into the other aspects of placement and safety. In most guns, there is simply no place to install the capacitors of a size that may even be useful. And then, there's safety aspects as well. If you use a polarized capacitor (which is required for DC circuits) and you accidentally reversed the polarity to it, it will explode. If you did this with a 25v 100mfd cap, there would be nothing left of the stock of your gun as the explosion will be significant. And you'd probably hurt yourself in the process.

That's why for our purposes, they are a complete waste of time.