Electronics are becoming ever more prevalent in my uni course (I’m doing sound engineering). Knowing how your own equipment works and stuff is integral but what is a capacitor. I failed physics in school almost. What does it do. Help.
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electricity is just electrons moving, if they don’t move then there’s no electricity, capacitors allow a certain amount of electrons to move, after a capacitor is ‘filled’ they don’t allow electrons to pass, inductors are the opposite, they don’t allow electrons to pass until they are filled
For sound engineering it’s more useful to think of a capacitor as a gate that only lets electricity through when there’s a voltage change. Different sized capacitors have different frequencies that they start to work at. So you can use capacitors in your circuits to act as frequency filters. You can put one on the path you want your signal to go, and it will filter out low frequencies (it’s a high pass filter). Or you can put one on a side street that goes nowhere interesting (“ground”), and it will detour the high-frequency stuff that way, pulling it out of your signal. So when used that way, it’s a low pass filter.
Capacitors also take a little time to charge, and you can change the amount of time by adding resistors and changing the capacitor size, so you can use capacitors to make delay elements too. You can make circuits that charge and then discharge, and the resultant waveform looks like an ugly sine wave. The frequency of the waveform depends on the sizes of the capacitors and resistors you chose. So you can use capacitors to make an oscillator or a synthesizer.
Other users have done a good job at explaining this, so I will talk about how I use capacitors for building quadcopters.
Racing/freestyle quadcopters mostly use 16.8-25.2v LiPo batteries, built for discharging hundreds of amps in short bursts. Usually, youd regulate your analog video transmitter and camera to 5v/9v using a buck converter. Any fluctuations in voltage can cause horrible noise and could easily lead to a dangerous crash since you cant see – these quadcopters dont hold your hand like Mavics, there is absolutely no support or obstacle avoidance etc, not even self leveling. These fluctuations also will ruin your microphone transmission, but most people dont use that on these quads. The motors create tons of back EMF and pretty much everything about these type of quadcopters is extremely noisy with tons of voltage fluctuations.
To solve this, you use capacitors to even out all of these fluctuations, charging up when the voltage spikes and releasing it when the voltage drops. Capacitors on your ESCs, capacitors on your cameras, caps helping out your regulators, sometimes caps directly on your battery leads etc. Without capacitors, a gust of wind or a throttle punch could make your video feed completely useless, but with correctly cap placement you can eliminate all the noise from the system, even from your analog microphone transmissions.
I’m sure this can be applied to many things in the audio world where you have a noisy power source for whatever reason.
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