C is for Capacitor

automatic captions, checked for structure and key terms; corrections welcome

[00:00:03.620] [unclear opening audio]
[00:00:30.420] Needle-nose pliers?
[00:00:32.060] Needle-nose pliers.
[00:00:34.040] Jumper wire.
[00:00:35.240] Jumper wire.
[00:00:37.260] Capacitor.
[00:00:38.740] Um, which one is the capacitor again?
[00:00:41.360] Oh, it's the blue round thing on the left.
[00:00:45.040] Aha!
[00:00:47.000] One capacitor.
[00:00:48.720] For you.
[00:00:49.800] Thanks, Adabot.
[00:00:51.980] Ladyada, what does a capacitor do?
[00:00:54.560] A capacitor stores electrical energy.
[00:00:57.520] But isn't that what a battery does?
[00:01:00.140] Well, yes, both a battery and a capacitor store electrical energy.
[00:01:04.560] But other than that, they're quite different.
[00:01:07.220] Oh, but what makes them different?
[00:01:09.480] Well, a battery generates electrical energy using chemistry,
[00:01:13.980] whereas a capacitor has to be charged from an external source
[00:01:17.700] before it can supply electrical energy.
[00:01:19.620] So a battery makes electricity, but a capacitor stores it.
[00:01:24.520] That's right.
[00:01:25.500] Can a capacitor be filled with electricity from a battery?
[00:01:29.160] Absolutely.
[00:01:30.360] Cool, but why would you want to do that?
[00:01:33.800] That's a good question. You might want to ask a capacitor.
[00:01:37.360] Good idea. I'll go ask Cappy.
[00:01:45.660] Hello, Cappy. How are you doing?
[00:01:48.460] Oh, hello there, Adabot. I'm doing quite fine. Yourself?
[00:01:51.520] All systems are fully operational, but I have a question. What do you do in this
[00:01:56.320] circuit?
[00:01:56.960] Oh, good question. In this circuit, I'm filtering power.
[00:02:01.540] Oh, how do you do that?
[00:02:03.480] Ah, well you see, this circuit is a power supply.
[00:02:06.840] We take electrical power in on one side, fix it up, smooth it out, and we send it
[00:02:11.740] out the other side.
[00:02:12.920] And I'm the part who does the smoothing.
[00:02:15.680] When too much electricity is coming in, I store the extra.
[00:02:19.380] And when too little electricity is coming in, I empty out my stored electricity to
[00:02:24.500] fill in the gaps.
[00:02:25.760] Wow, I guess you're a pretty powerful guy around here.
[00:02:29.160] You might say that, kiddo, you might.
[00:02:31.560] But capacitors do more than just filter power.
[00:02:34.560] Really? What else do they do?
[00:02:36.660] Ah, let's see.
[00:02:51.240] Capacitors store lots of power to help keep photos brightly lit.
[00:02:55.180] A camera flash?
[00:02:56.380] Precisely.
[00:02:57.720] When the power goes out, capacitors can help a computer run for a bit.
[00:03:02.540] Backup power?
[00:03:03.580] Right again.
[00:03:05.560] A capacitor can let low notes play while filtering out the higher ranges.
[00:03:10.060] That's an audio filter.
[00:03:11.720] Correct. Capacitors can block electron flow while passing along electrical changes.
[00:03:17.560] Uh, I don't know that one.
[00:03:19.380] Oh, that is kind of a tough one. It's called AC Coupling. Don't worry about it.
[00:03:25.260] Okay.
[00:03:26.880] There's just one more thing you should know. Some capacitors can dance.
[00:03:31.580] What?
[00:03:43.480] Capacitors do a lot of important work inside of circuits by storing and releasing
[00:03:47.640] electrical energy.
[00:03:50.520] Agreed. But where do you store all that energy? Some kind of backpack or big pocket?
[00:03:55.220] No, I store electrical energy right here in my body.
[00:03:59.140] Whoa!
[00:04:03.920] Inside every capacitor there are two electrically conductive plates,
[00:04:09.780] separated by a layer of material that doesn't conduct electricity.
[00:04:13.660] electricity. Electrical energy is stored in a capacitor when many
[00:04:19.260] electrons gather on
[00:04:20.480] one plate, all trying to reach the other plate which has more empty spaces for the
[00:04:26.460] electrons
[00:04:27.000] to fill. Oh, just like in a battery, the electrons crowd up on one
[00:04:32.700] side, hoping they can fill
[00:04:34.000] the empty spaces. Indeed. And, a capacitor releases electrical
[00:04:39.420] energy when those electrons
[00:04:41.240] find an easier way to get to those open spaces by going outside
[00:04:46.920] of the capacitor's body.
[00:04:51.640] Thanks, capacitors make a lot more sense now.
[00:04:54.520] You're very welcome Adabot, glad I could help. Oh that reminds me,
[00:04:59.180] I should get back to work at that power supply circuit.
[00:05:02.220] Right, see you later Cappy.
[00:05:08.420] Oh, hey, welcome back, Adabot. So, did Cappy tell you all about capacitors?
[00:05:12.520] He did. He's a pretty amazing guy. Capacitors can be used in all sorts of
[00:05:16.840] different ways.
[00:05:18.160] That's right. They also come in many different sizes and colors, like these.
[00:05:23.060] Wow, those are all capacitors?
[00:05:25.360] That's right. Different types of capacitors for different types of jobs.
[00:05:29.200] from teeny disks to ceramics, film, and electrolytic capacitors.
[00:05:34.340] We even have huge super caps.
[00:05:38.660] Let's try and experiment with this capacitor.
[00:05:42.680] This fellow has 10,000 microfarads of capacitance and can be used up to 6.3 volts.
[00:05:48.120] I'm going to measure the voltage on this empty capacitor with my multimeter.
[00:05:54.120] Right now we're at zero volts.
[00:05:57.520] Now I'm going to charge my capacitor with these two AA batteries.
[00:06:01.560] All I have to do is touch the leads to the capacitor to charge it up to 2.5 volts.
[00:06:09.280] Now we can use the stored energy inside this capacitor to light up an LED.
[00:06:17.160] Ladyada, there's still one thing I'd like to know.
[00:06:20.220] What's that, Adabot?
[00:06:21.040] Well, why don't your capacitors dance?
[00:06:23.980] What?
[00:06:24.460] You know, do-da-do-da-do-do-do-do-dee-do.
[00:06:28.680] Do-da-do-da-do-do-do-do-do-do-do-da.
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