I understand that capacitors store and release energy, but I don't quite understand why they are used in stuff like computers, radios, and pretty much every other electronic device you can buy. I'm kind of a noob so please try to not use big words, I probably won't understand them.

 

Starting on only one cup of coffee...
The power lines bring us AC voltage and current because it is convenient to control the long line voltages with transformers.
When we connect simple things like a water heater or a primitive battery charger, lumpy sine waves don't hurt anything.
It is only when we need smooth DC to run things that the lumps interfere. That's where the aluminum electrolytic filter capacitors show up. After that, the faster the logic switches, the more we get trouble from inductance in things as small as circuit board traces. Suddenly you need a tiny capacitor every few inches to keep the logic chips from interfering with each other by causing wobbles in the DC power line on the circuit board.

That's a start. Let's see where this goes.

 

In 140 characters or less? Yeah, I'll get right on it. Hold your breath while I do it for you.

HA, changed my mind.

There is a newly invented thing called a search engine. It let's lazy people look up facts and fictions on any subject one can imagine and several I try hard not to. Maybe, just maybe, you can find out about capacitors there.

 

Every component in a circuit controls either the amount of the current or the rate of change of the current.

A resistor can only control the amount of current by using heat. Which is power.

A capacitor can do either/both without using power.

 

Hello,

The functions of capacitors can be different all over the circuit.
There are capacitors for buffering, like the buffer capacitor in a power supply or the decoupling capacitor near the chips in a circuit.
There are capacitors used as blocking capacitors. These are used to block DC and pass the AC signal, as in an amplifier.

For info on the DC properties of a capacitor, you could have a look at this chapter of the eBook:
https://www.allaboutcircuits.com/textbook/direct-current/chpt-13/electric-fields-capacitance/
For info on the AC properties of a capacitor, you could have a look at this chapter of the eBook:
https://www.allaboutcircuits.com/te...rrent/chpt-4/ac-resistor-circuits-capacitive/

For more info on the use as decoupling capacitors, have a look at this thread:
Decoupling or Bypass Capacitors, Why?

Bertus

 

I understand that capacitors store and release energy, but I don't quite understand why they are used in stuff like computers, radios, and pretty much every other electronic device you can buy. I'm kind of a noob so please try to not use big words, I probably won't understand them.

This is somewhat like asking why metal is used in a car. There are lots of different uses and the reason that metal is used in the crankshaft is different than why metal is used in the door switch.

Same with capacitors. In different parts of the circuit they do different things. In some places it is to store energy so that they can act as a short-term source of power when the primary power source is fluctuating. In other places it is because the effective resistance of a capacitor is different at different frequencies and therefore you can make circuits that behave differently at different frequencies. There are other uses as well, such as in sample-and-hold circuits.

 

There's no ideal capacitor. Each type may highlight a particular ideal feature.

A real capacitor has inductance (primarily leads), effective series resistance, a parallel resistance (leakage),a voltage limitation, a polarity limitation, a frequency limitation, the method of failure.

Sometimes different types (construction) of capacitor must be paralleled.

There are times when three 1K resistors in series cannot be replaced by one of the series combination.
In SOME cases a SMT resistor mounted on it's side must be used rather than mounted flat. This is due to trying to minimize parasitics (the unintended, but inevitable inductance, capacitance and resistance) of real components.

 

I understand that capacitors store and release energy, but I don't quite understand why they are used in stuff like computers, radios, and pretty much every other electronic device you can buy. I'm kind of a noob so please try to not use big words, I probably won't understand them.

Not *ALL* circuits have capacitors - I've seen a few motorcycle voltage regulators that didn't.

Big capacitors store enough charge to act as reservoirs on PSU rails. AC on one plate influences the other plate, so they can couple AC from one part of a circuit to another while blocking DC - a bit of a grey area is "decoupling" supply rails. The plate that would be influenced is tied to GND and (hopefully) can't move, the other plate which does the influencing; because of the AC coupling - can't move either. This supplements the reservoir caps by damping out faster disturbances. Mathematically; capacitance and inductance are exact opposites - putting matched values in series or parallel doesn't cancel out - something magical happens. With theoretical ideal components - at resonance; extraordinary voltages or currents can be developed as if there was something for nothing. In the real world, losses stop us getting something for nothing, but an LC circuit at resonance will give a perception of gain, so a tuned circuit can be made to work very well at the frequency you want, and very poorly at any other frequency.

 

I understand that capacitors store and release energy, but I don't quite understand why they are used in stuff like computers, radios, and pretty much every other electronic device you can buy. I'm kind of a noob so please try to not use big words, I probably won't understand them.

Your question is of a basic nature but a very valid one.

You will find many different components in an electronic circuit, resistors, capacitors, inductors, diodes, transistors, ICs etc.
Each component has a specific function depending on where and how it is used.
It is like asking where and why would one use a nail, screw, bolt, cement or glue when building a house.

Don't be afraid to ask questions of this nature. This is what the AAC forum as all about.

 

In 140 characters or less? Yeah, I'll get right on it. Hold your breath while I do it for you.

HA, changed my mind.

There is a newly invented thing called a search engine. It let's lazy people look up facts and fictions on any subject one can imagine and several I try hard not to. Maybe, just maybe, you can find out about capacitors there.

Kermit2, You are one of the reasons why people are afraid to ask questions.
How can you search for something if you don't know what to search for?
I am also new to electronics, I find it fascinating as I learn more about them, unfortunately there are some things that I cannot properly put into words (Or simply don't know what to ask for).

If you are here to bash people on their lack of knowledge, it would be better if you simply do not post any replies to such posts. If you are having trouble understanding what I am trying to say, allow me to post in more easier words that you could understand:

So far, everyone posted valid answers, tried to explain it in a proper manner. You just bashed a question that someone actually wanted to know.
The original question was valid. OP wanted to learn something that was curious about and didn't know to address the question, so it was posted in most generic way possible. An invalid request would be "Teach me electronics".

Note to Admins, Mods: If this was too much, feel free to delete my reply of mod it in any way you see fit. I just wanted to vent my frustration.

MOD NOTE: Obscenity removed.

 

Okay, Lets say that it is a ceramic capacitor hooked up between the positive and negative ends, what would it's purpose be?

 

Think of it as a miniature battery. When power is applied, if stores a little bit of voltage in it. Once it is full, it sends the input voltage to the circuit. When power is removed, it discharges into the circuit until it reaches zero volts.

 

Okay, Lets say that it is a ceramic capacitor hooked up between the positive and negative ends, what would it's purpose be?

The positive and negative ends of what?
The capacitor will not allow a continuous DC current to flow through it, but it will allow sudden changes in voltage to somewhat shoot right through the capacitor. Thus, sudden small changes in voltage almost completely disappear from the two places where the capacitor is connected. Do this on a digital chip and it will be effective. Do it to a 5 HP DC motor and you're pissin' in the wind.

 

The positive and negative ends of what?
The capacitor will not allow a continuous DC current to flow through it, but it will allow sudden changes in voltage to somewhat shoot right through the capacitor. Thus, sudden small changes in voltage almost completely disappear from the two places where the capacitor is connected. Do this on a digital chip and it will be effective. Do it to a 5 HP DC motor and you're pissin' in the wind.

The positive and negative ends of a CPU.

 

The positive and negative ends of a CPU.

Perfect example of a high speed switching chip. The fast changes of need for current are supplied by the capacitor quicker than the current can arrive from the power supply, several inches away. Yes, a CPU switches so fast that an inch of circuit board copper affects how fast it can get power from the power supply.

 

I understand that capacitors store and release energy, but I don't quite understand why they are used in stuff like computers, radios, and pretty much every other electronic device you can buy.

Short answer - because "computers, radios, and pretty much every other electronic device you can buy" function by storing and releasing energy in some manner. Oscillators, amplifiers, big power supplies, little power regulators, radios, etc. all require energy in motion to achieve their operation.

ak

 

The positive and negative ends of a CPU.

If I understand you correctly, we normally refer to them as supply/ground pins.

Caps connected across the power pins can both prevent power sag and bypass (decouple) noise to ground. The impedance of a capacitor is \( \small Xc = \frac{1}{2\pi fC}\). Because capacitors aren't ideal, due to parasitic resistance and inductance, a larger value cap doesn't always have a smaller impedance at higher frequencies; so 10-100nF caps are used in parallel with larger capacitors that prevent power sag.

A conservative rule of thumb for decoupling caps is one per power pin. Power grid analysis will dictate how far you can back off from that.

If I used any words you don't understand, Google them or ask questions; preferably Google first.

 

Kermit2, You are one of the reasons why people are afraid to ask questions.

In fairness to @Kermit2, sometimes we see a question like yours when we're not in the mood to be able to tolerate someone who wants to hang with the big boys, but doesn't have the goods.

If you tried asking a specific question instead of one that's very vague and/or general, you might get responses more to your liking.

EDIT: reread the thread and noticed that it wasn't the OP who was complaining. To the OP; my apologies for accusing you of complaining about abuse.

 

Kermit2, You are one of the reasons why people are afraid to ask questions.

Sometimes I wake up wanting to, "kick the cat" and I don't even have a cat.
But, yes, the right thing to do is: don't turn the computer on until I feel better.
Failing that, this site provides an, "Ignore" function. I use it often to "disappear" people that I simply can not understand.
There are dozens of good people here, and someone almost always accomplishes real communication, but nobody can understand everybody. When you meet one that makes your head tend to explode, it's time to click something else.

 

When you meet one that makes your head tend to explode, it's time to click something else.

Most of the people on my ignore list are the ones who constantly ask vague questions or refuse to help us help them.