#256 - Capacitor types, characteristics, and applications

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Language: en

00:00:00.030
in today's video we're going to talk
00:00:02.030 00:00:02.040 about capacitors talk about the
00:00:04.220 00:00:04.230 different types of capacitors that
00:00:05.660 00:00:05.670 you'll run across some of their basic
00:00:07.610 00:00:07.620 characteristics and the applications
00:00:09.770 00:00:09.780 we'll use each of these different types
00:00:11.450 00:00:11.460 of capacitors certainly the most common
00:00:14.030 00:00:14.040 two types of capacitors that you'll run
00:00:15.650 00:00:15.660 across and use are multi layer or
00:00:18.260 00:00:18.270 monolithic ceramic capacitors and
00:00:20.529 00:00:20.539 electrolytic capacitors so let's talk
00:00:22.670 00:00:22.680 about both of those first let's start
00:00:24.380 00:00:24.390 with the electrolytic probably the most
00:00:27.529 00:00:27.539 common electrolytic capacitors you run
00:00:29.359 00:00:29.369 across of the aluminum electrolytic I've
00:00:32.120 00:00:32.130 got some radial and axial eated examples
00:00:35.240 00:00:35.250 here as well as some surface mount parts
00:00:38.139 00:00:38.149 electrolytic SAR typically you know from
00:00:40.580 00:00:40.590 about 1 microfarad to maybe well over 1
00:00:43.160 00:00:43.170 farad with some working voltages from 5
00:00:45.680 00:00:45.690 volts to sometimes well over 500 volts
00:00:48.100 00:00:48.110 just about all of them are polarized
00:00:50.389 00:00:50.399 there are some non polarized examples
00:00:52.939 00:00:52.949 that you can get non polarized
00:00:54.619 00:00:54.629 electrolytic s-- they're typically used
00:00:56.569 00:00:56.579 in like audio crossovers for speaker
00:00:58.580 00:00:58.590 crossover networks but the vast majority
00:01:00.410 00:01:00.420 of the electrolytic still find our
00:01:02.299 00:01:02.309 polarized capacitors and there'll be you
00:01:04.460 00:01:04.470 know marked as such you'll usually have
00:01:06.160 00:01:06.170 one side of the other usually the
00:01:08.359 00:01:08.369 negative side marked on the aluminum
00:01:09.980 00:01:09.990 00:01:12.770 00:01:12.780 for things like power supply filtering
00:01:15.530 00:01:15.540 for relatively low frequency
00:01:16.880 00:01:16.890 applications typically below 100
00:01:19.160 00:01:19.170 kilohertz because above that their self
00:01:21.649 00:01:21.659 president frequency starts getting in
00:01:23.450 00:01:23.460 the way and they don't really work like
00:01:24.830 00:01:24.840 very good capacitors anymore they do
00:01:27.770 00:01:27.780 have an unfortunate wear out mechanism
00:01:29.749 00:01:29.759 especially accelerated by heat that
00:01:32.090 00:01:32.100 causes the electrolyte within these
00:01:34.730 00:01:34.740 capacitors to dry out which causes the
00:01:37.130 00:01:37.140 ESR or dissipation factor can rise that
00:01:41.870 00:01:41.880 causes an increase in temperature with
00:01:43.370 00:01:43.380 ripple currents and that accelerates the
00:01:44.990 00:01:45.000 failure and that's a very common failure
00:01:47.090 00:01:47.100 mode for these types of devices they
00:01:49.370 00:01:49.380 also have some what we call so kajoor
00:01:51.440 00:01:51.450 dielectric absorption issues what that
00:01:53.630 00:01:53.640 means is that if they've got a DC bias
00:01:55.670 00:01:55.680 applied to them for a while and then you
00:01:58.219 00:01:58.229 short the capacitor out to discharge the
00:02:00.319 00:02:00.329 capacitor then remove the short the some
00:02:03.469 00:02:03.479 voltage will actually come back due to
00:02:05.780 00:02:05.790 the polarization that happened within
00:02:07.429 00:02:07.439 the electric electrolyte I'll actually
00:02:09.139 00:02:09.149 show you this here in a moment it's
00:02:10.520 00:02:10.530 pretty interesting the other thing about
00:02:12.619 00:02:12.629 these
00:02:13.699 00:02:13.709 electrolytic tap so that the leakage
00:02:15.170 00:02:15.180 increases pretty dramatically with
00:02:16.819 00:02:16.829 temperature the capacitance will also
00:02:19.250 00:02:19.260 change with temperature so and if you've
00:02:21.800 00:02:21.810 got an application where you need to do
00:02:23.300 00:02:23.310 rapid charge or discharge like four
00:02:25.569 00:02:25.579 flashes and things like that you
00:02:27.440 00:02:27.450 definitely need to specify special parts
00:02:29.720 00:02:29.730 because your ordinary aluminum
00:02:31.789 00:02:31.799 electrolytic sarn't designed for high
00:02:33.289 00:02:33.299 currents like that but they do have a
00:02:35.119 00:02:35.129 very high capacitance density per unit
00:02:37.369 00:02:37.379 volume and that's what makes them very
00:02:39.619 00:02:39.629 popular because they're really good for
00:02:41.660 00:02:41.670 things like power supply filtering
00:02:43.250 00:02:43.260 you'll often see them next to power
00:02:45.710 00:02:45.720 supply regulators another places where
00:02:48.800 00:02:48.810 you want to quiet down a bias or
00:02:50.330 00:02:50.340 something you know bias voltage or
00:02:51.740 00:02:51.750 something like that because they're
00:02:52.670 00:02:52.680 really good for low-frequency power
00:02:54.770 00:02:54.780 supply decoupling and bypassing they're
00:02:57.890 00:02:57.900 also pretty good for low to medium
00:03:00.259 00:03:00.269 frequency bypassing you know in
00:03:02.629 00:03:02.639 amplifiers and things like that but they
00:03:05.240 00:03:05.250 are accused
00:03:05.750 00:03:05.760 there's certainly applications for them
00:03:07.940 00:03:07.950 there they can be used for some
00:03:09.709 00:03:09.719 non-critical low frequency timing
00:03:11.869 00:03:11.879 applications but because of things like
00:03:13.940 00:03:13.950 the absorption characteristics the
00:03:16.339 00:03:16.349 temperature changes and especially the
00:03:19.449 00:03:19.459 you know some of the instabilities you
00:03:22.819 00:03:22.829 don't want to use them for anything
00:03:23.990 00:03:24.000 where you need any critical kind of
00:03:25.280 00:03:25.290 timing but energy storage applications
00:03:28.009 00:03:28.019 great at low frequency stage coupling
00:03:30.500 00:03:30.510 between one stage or another they're
00:03:32.240 00:03:32.250 just fine we typically do not want to
00:03:34.699 00:03:34.709 use them for critical timing circuits as
00:03:36.530 00:03:36.540 I measured I mentioned triggering
00:03:38.629 00:03:38.639 circuits where you need really precise
00:03:40.129 00:03:40.139 amount of charge stored there that you
00:03:41.719 00:03:41.729 might use to to trigger another circuit
00:03:43.670 00:03:43.680 and definitely not in any circuits where
00:03:46.490 00:03:46.500 you need precise frequency determination
00:03:49.399 00:03:49.409 or phase shift circuits and the
00:03:51.110 00:03:51.120 generally don't have any place in any RF
00:03:53.689 00:03:53.699 circuits because of the relatively low
00:03:56.170 00:03:56.180 self resonant frequency just because
00:03:59.300 00:03:59.310 it's so interesting let's take a quick
00:04:00.530 00:04:00.540 look at this so future dielectric
00:04:02.689 00:04:02.699 absorption issue here is just a little
00:04:05.659 00:04:05.669 one microfarad electrolytic capacitor
00:04:08.420 00:04:08.430 what I charged up to just about 12 volts
00:04:10.670 00:04:10.680 you can see on the voltmeter there it's
00:04:13.369 00:04:13.379 just about exactly 12 volts now if I
00:04:15.949 00:04:15.959 pull the power supply off of this you
00:04:17.870 00:04:17.880 see the voltage is starting to drop is
00:04:19.909 00:04:19.919 just leakage and and some card that's
00:04:21.830 00:04:21.840 going into the meter
00:04:23.570 00:04:23.580 let's short these leads out here so I
00:04:26.300 00:04:26.310 short the leads out look at SU
00:04:27.620 00:04:27.630 drop down now - you know there's 200
00:04:29.840 00:04:29.850 microvolts but watch what happens when I
00:04:31.550 00:04:31.560 remove the short the boulders are
00:04:34.700 00:04:34.710 ramping back up again and you know
00:04:36.860 00:04:36.870 pretty soon here we are at 75 millivolts
00:04:39.620 00:04:39.630 80 millivolts it's going to go well over
00:04:42.200 00:04:42.210 a hundred millivolts here so we're
00:04:45.290 00:04:45.300 ramping up here and oh now we're at 125
00:04:48.140 00:04:48.150 millivolts and our 1% of the voltage
00:04:50.300 00:04:50.310 that I was applied to it before and I
00:04:52.820 00:04:52.830 had that discharge for from electronic
00:04:55.100 00:04:55.110 standpoint a pretty long time
00:04:56.540 00:04:56.550 let's short that out again get back down
00:04:59.270 00:04:59.280 here and down around 3 micro volts there
00:05:02.030 00:05:02.040 3 milli volts let go of it again and we
00:05:04.700 00:05:04.710 see it ramping up again this is again
00:05:07.130 00:05:07.140 dielectrics okage and it can really
00:05:10.460 00:05:10.470 wreak havoc with precision timing
00:05:11.960 00:05:11.970 circuits but before we leave the topic
00:05:13.670 00:05:13.680 of polarized capacitors let's talk about
00:05:15.800 00:05:15.810 the other type that you'll see and
00:05:17.450 00:05:17.460 that's typically these tantalum
00:05:18.920 00:05:18.930 capacitors I've got a couple of examples
00:05:20.930 00:05:20.940 here some radial eaded and then a little
00:05:25.520 00:05:25.530 surface mount device here tantalum caps
00:05:28.400 00:05:28.410 are old again they're all polarized and
00:05:30.740 00:05:30.750 I would say there are wildly polarized
00:05:32.780 00:05:32.790 in all places I mean by that here in a
00:05:34.520 00:05:34.530 moment but they're typically you know
00:05:37.430 00:05:37.440 ranging from you know about you know
00:05:39.920 00:05:39.930 0.12 1 microfarad up to a thousand
00:05:42.170 00:05:42.180 microfarads or so but they're relatively
00:05:44.120 00:05:44.130 low voltage they won't go up to the
00:05:45.560 00:05:45.570 hundreds of volts typically that the
00:05:47.780 00:05:47.790 electrolytic swill they do have a higher
00:05:51.050 00:05:51.060 capacitance density than the
00:05:52.550 00:05:52.560 electrolytic so for a given package size
00:05:54.770 00:05:54.780 you can get a larger value of
00:05:57.020 00:05:57.030 capacitance with the 10 ohms than you
00:05:59.480 00:05:59.490 can with the electrolytic s-- they are
00:06:01.670 00:06:01.680 very intolerant of reverse bias though
00:06:05.480 00:06:05.490 you know a little bit of reverse bias on
00:06:07.550 00:06:07.560 an electrolytic it may leak a little bit
00:06:09.680 00:06:09.690 you might accelerate the failure
00:06:11.180 00:06:11.190 mechanism but they're going to be pretty
00:06:13.250 00:06:13.260 tolerant of it but atoms can get pretty
00:06:15.830 00:06:15.840 exciting when tantalum fail they
00:06:18.620 00:06:18.630 generally fail short-circuit and then
00:06:21.050 00:06:21.060 oftentimes will burn catch fire close
00:06:24.290 00:06:24.300 some damage and things like that so as
00:06:26.360 00:06:26.370 long as you treat them right they're
00:06:27.830 00:06:27.840 actually pretty good reliable capacitors
00:06:29.750 00:06:29.760 but do not over voltage them and do not
00:06:33.110 00:06:33.120 reverse bias them they don't have the
00:06:36.200 00:06:36.210 wear out mechanism not the aluminum
00:06:38.600 00:06:38.610 electrolytic stew but they are pricier
00:06:40.640 00:06:40.650 than the
00:06:41.239 00:06:41.249 electrolitic generally I've got nice low
00:06:43.519 00:06:43.529 ESR there a bit more temperature and
00:06:46.039 00:06:46.049 voltage stable than the aluminum
00:06:47.869 00:06:47.879 electrolytic SAR but again they're a
00:06:50.899 00:06:50.909 little bit pricier so you do have to pay
00:06:52.369 00:06:52.379 for that so the applications are very
00:06:54.889 00:06:54.899 similar to the aluminum electrolytic
00:06:57.289 00:06:57.299 power supply filtering low to medium
00:07:00.259 00:07:00.269 frequency bypassing energy storage and
00:07:03.019 00:07:03.029 long duration timing again that is not
00:07:04.939 00:07:04.949 super critical
00:07:06.109 00:07:06.119 although the characteristics okage
00:07:09.049 00:07:09.059 characteristics and tolerance
00:07:11.059 00:07:11.069 characteristics of the ten ohms are
00:07:12.349 00:07:12.359 general a little bit better than the
00:07:13.850 00:07:13.860 aluminum electrolytic s-- but they're
00:07:15.889 00:07:15.899 not good for high voltage applications
00:07:17.589 00:07:17.599 or cost sensitive applications of course
00:07:20.449 00:07:20.459 or anything it's got any large AC
00:07:22.399 00:07:22.409 signals that might even momentarily
00:07:24.079 00:07:24.089 reverse bias them and similarly their
00:07:27.319 00:07:27.329 self resident frequency is low enough
00:07:29.089 00:07:29.099 that you're not going to really use them
00:07:30.649 00:07:30.659 too much for RF applications although
00:07:32.539 00:07:32.549 they the ESR of them is a little bit
00:07:34.850 00:07:34.860 better and than it is with the aluminum
00:07:37.759 00:07:37.769 electrolytic outside of the
00:07:41.449 00:07:41.459 low-frequency power supply filtering and
00:07:43.879 00:07:43.889 decoupling caps and things like that
00:07:46.119 00:07:46.129 you'll most likely find ceramic
00:07:48.799 00:07:48.809 capacitors certainly the most common
00:07:50.600 00:07:50.610 that are out there and with most modern
00:07:52.279 00:07:52.289 electronics being surface mount is a
00:07:54.259 00:07:54.269 vast majority of small surface but
00:07:56.659 00:07:56.669 capacitors or these multi-layer ceramic
00:07:58.189 00:07:58.199 devices like are shown here lots of
00:08:01.069 00:08:01.079 different package styles from the disc
00:08:03.469 00:08:03.479 capacitors to these kind of molded
00:08:05.899 00:08:05.909 monolithic type devices and dipped
00:08:07.699 00:08:07.709 monolithic devices like that one there
00:08:09.879 00:08:09.889 now the capacitance and voltage range
00:08:12.709 00:08:12.719 for these can range anywhere from you
00:08:14.209 00:08:14.219 know under a Pico farad to well over 500
00:08:16.339 00:08:16.349 micro farad and even available with
00:08:18.439 00:08:18.449 working voltages to well over a thousand
00:08:20.869 00:08:20.879 volts now there are a lot of different
00:08:23.239 00:08:23.249 types of ceramic capacitors and they're
00:08:25.369 00:08:25.379 kind of divided among the different
00:08:27.619 00:08:27.629 types of dielectric and the
00:08:29.839 00:08:29.849 characteristics of that dielectric the
00:08:33.350 00:08:33.360 class 1 dielectrics different types
00:08:36.439 00:08:36.449 called np0 and c 0g these class 1
00:08:41.869 00:08:41.879 devices are very very stable devices
00:08:44.929 00:08:44.939 with temperature they male they vary by
00:08:46.519 00:08:46.529 a few percent over a very wide
00:08:47.929 00:08:47.939 temperature range they're available with
00:08:50.119 00:08:50.129 a very tight tolerance and but they're
00:08:52.340 00:08:52.350 typically low value devices from
00:08:54.650 00:08:54.660 send a picofarad - maybe up as high as a
00:08:56.840 00:08:56.850 micro farad but typically you know tens
00:08:59.540 00:08:59.550 of nano ferrets or less now because
00:09:02.480 00:09:02.490 there are low values of capacitance and
00:09:05.000 00:09:05.010 they're very stable they find themselves
00:09:06.410 00:09:06.420 to work very very well in RF
00:09:09.140 00:09:09.150 applications and that's where you'll
00:09:10.550 00:09:10.560 find these very common there now the
00:09:13.400 00:09:13.410 class - dielectric materials they vary a
00:09:17.420 00:09:17.430 bit more with both temperature and with
00:09:20.720 00:09:20.730 applied voltage so they're not quite as
00:09:25.820 00:09:25.830 precise and not quite as stable but they
00:09:27.620 00:09:27.630 are available in larger values now the
00:09:30.260 00:09:30.270 letter designations actually will relate
00:09:32.900 00:09:32.910 to the temperature range and the amount
00:09:35.180 00:09:35.190 of variation that they have over a given
00:09:37.160 00:09:37.170 temperature range it's probably worth a
00:09:39.110 00:09:39.120 whole other video just to talk about
00:09:40.370 00:09:40.380 that but we'll just kind of leave it put
00:09:42.290 00:09:42.300 some of the common values that you'll
00:09:43.520 00:09:43.530 see here some of the common class to
00:09:45.920 00:09:45.930 dielectric types that you'll see are x7r
00:09:48.050 00:09:48.060 capacitors y5v z5u these are all kind of
00:09:53.000 00:09:53.010 class two dielectrics let's take a look
00:09:55.070 00:09:55.080 at this little chart over here this is a
00:09:57.290 00:09:57.300 chart showing relative capacitance
00:09:59.630 00:09:59.640 change versus temperature and this is
00:10:02.900 00:10:02.910 very shallow little linear line here
00:10:05.240 00:10:05.250 that's your NP 0 and C 0 G capacitors
00:10:08.180 00:10:08.190 the x7r capacitors might vary plus or
00:10:12.620 00:10:12.630 minus 10 or 15% around their original
00:10:15.530 00:10:15.540 value or their nominal value over that
00:10:18.230 00:10:18.240 temperature range so that's not too bad
00:10:20.180 00:10:20.190 but that's still a pretty good variation
00:10:22.450 00:10:22.460 the y5v and z5u they're kind of horrible
00:10:27.590 00:10:27.600 it comes to a temperature variation they
00:10:30.140 00:10:30.150 may go up as high as 10 or 15% over
00:10:32.840 00:10:32.850 their nominal value but drop down to 60
00:10:35.840 00:10:35.850 or 70 or even 80% of their look below
00:10:39.470 00:10:39.480 their nominal value at the temperature
00:10:41.720 00:10:41.730 extremes they also have got a higher
00:10:44.570 00:10:44.580 dissipation factor and well and both of
00:10:47.030 00:10:47.040 the class twos are somewhat voltage
00:10:50.300 00:10:50.310 dependent as well where the capacitance
00:10:52.640 00:10:52.650 will change with applied voltage but you
00:10:55.940 00:10:55.950 get larger capacitance values so you
00:10:58.940 00:10:58.950 know you'll find that the y5v and z5u
00:11:01.760 00:11:01.770 caps you know they're available in very
00:11:03.440 00:11:03.450 large values they'll be used for
00:11:05.000 00:11:05.010 non-critical bypass applications where
00:11:07.890 00:11:07.900 you can accept that kind of a large
00:11:09.630 00:11:09.640 tolerance and the value the x7r is a
00:11:13.110 00:11:13.120 reasonable compromise between the
00:11:16.170 00:11:16.180 stability of the class 1 dielectrics but
00:11:19.350 00:11:19.360 the larger values of the y5v and z5u
00:11:22.380 00:11:22.390 materials so if you have a choice for a
00:11:24.870 00:11:24.880 given value in your application between
00:11:29.160 00:11:29.170 x7r caps and the Y or Z type caps go
00:11:32.700 00:11:32.710 with the x7 RS are going to be a bit
00:11:34.260 00:11:34.270 more stable all of the ceramic caps are
00:11:37.230 00:11:37.240 generally pretty low cost they got low
00:11:39.560 00:11:39.570 dissipation factor loius are good RF
00:11:43.470 00:11:43.480 performance but ceramic materials are
00:11:46.019 00:11:46.029 also microphonic so if they're in a high
00:11:48.300 00:11:48.310 vibration environmental things like that
00:11:50.420 00:11:50.430 that can actually cause the capacitor to
00:11:53.070 00:11:53.080 become a little bit microphonic almost
00:11:55.260 00:11:55.270 like a quartz type of device so you have
00:11:57.630 00:11:57.640 to kind of be aware of that so again
00:12:00.150 00:12:00.160 typically good for RF applications
00:12:02.250 00:12:02.260 they're very low cost bypassing
00:12:04.200 00:12:04.210 interstage coupling decoupling around
00:12:08.220 00:12:08.230 gain stages and things like that the
00:12:09.990 00:12:10.000 good applications for that generally not
00:12:12.750 00:12:12.760 so good for use in voltage controlled
00:12:15.480 00:12:15.490 oscillator designs or frequency
00:12:17.160 00:12:17.170 generation designs because of the
00:12:20.130 00:12:20.140 variation over temperature the class one
00:12:23.430 00:12:23.440 like MP 0 and C 0 G are the exception
00:12:26.130 00:12:26.140 here they certainly can work very well
00:12:27.630 00:12:27.640 in those applications they're not really
00:12:30.870 00:12:30.880 good for low frequency filtering where
00:12:34.890 00:12:34.900 you can't really withstand this kind of
00:12:37.170 00:12:37.180 tolerance with temperature so especially
00:12:39.449 00:12:39.459 the Y 5 e and z 5 you are really bad an
00:12:42.720 00:12:42.730 x 7r wouldn't be so bad for that
00:12:44.610 00:12:44.620 application but very very common types
00:12:46.920 00:12:46.930 of capacitors you'll find all over the
00:12:48.960 00:12:48.970 place in many many different packaged
00:12:51.329 00:12:51.339 styles now something I'll mention at
00:12:54.480 00:12:54.490 this point is if you're reviewing a
00:12:56.040 00:12:56.050 schematic or you see something online
00:12:57.720 00:12:57.730 they're going to go build and the
00:12:59.430 00:12:59.440 capacitors aren't labeled in terms of
00:13:01.380 00:13:01.390 what types they are whether they're
00:13:03.120 00:13:03.130 ceramics electrolytic so film or mica or
00:13:05.460 00:13:05.470 whatever the most likely case is that
00:13:08.040 00:13:08.050 any of the polarized caps are
00:13:09.840 00:13:09.850 electrolytic caps and in many cases
00:13:11.850 00:13:11.860 could be substituted with tantalum x'
00:13:13.680 00:13:13.690 any of the others that are non polarized
00:13:16.620 00:13:16.630 to generally lower value caps the most
00:13:18.870 00:13:18.880 likely ceramic capacitors if the
00:13:21.060 00:13:21.070 application
00:13:21.660 00:13:21.670 you know really warranted something
00:13:23.730 00:13:23.740 other than those two you know hopefully
00:13:25.830 00:13:25.840 the schematic would be labeled that way
00:13:27.690 00:13:27.700 but it's a pretty safe assumption that
00:13:29.460 00:13:29.470 for the polarized caps will be
00:13:31.020 00:13:31.030 electrolytic non polarized or ceramic
00:13:33.360 00:13:33.370 but that being said let's go take a look
00:13:35.790 00:13:35.800 at some of the other common types of
00:13:37.140 00:13:37.150 capacitors that are out there and some
00:13:38.970 00:13:38.980 of their characteristics and see where
00:13:40.470 00:13:40.480 they'd be applicable probably the next
00:13:43.080 00:13:43.090 most common type of capacitors are the
00:13:45.300 00:13:45.310 film capacitors now they're again just
00:13:47.610 00:13:47.620 like the ceramics there are many
00:13:49.020 00:13:49.030 different types of film capacitors one
00:13:52.080 00:13:52.090 of the differences though here is that
00:13:53.580 00:13:53.590 there are that many film capacitors that
00:13:56.160 00:13:56.170 are available in surface mount or
00:13:57.660 00:13:57.670 certainly not nearly as many as there
00:13:59.550 00:13:59.560 are for ceramic but there's actually
00:14:01.620 00:14:01.630 some really nice characteristics of film
00:14:03.510 00:14:03.520 capacitors that make them worth taking a
00:14:05.280 00:14:05.290 look at so some of the things that film
00:14:07.710 00:14:07.720 capacitors have in common is that
00:14:09.150 00:14:09.160 they're generally available from you
00:14:11.040 00:14:11.050 know the low tens of Pico farad's to you
00:14:13.410 00:14:13.420 know in the neighborhood of you know
00:14:14.700 00:14:14.710 even a thousand microfarad very large
00:14:16.830 00:14:16.840 values and working voltages from
00:14:19.590 00:14:19.600 relatively low voltages to well over a
00:14:22.170 00:14:22.180 thousand volts so very wide capacitance
00:14:27.510 00:14:27.520 and voltage range generally the film
00:14:29.910 00:14:29.920 caps have got really tight tolerances
00:14:31.800 00:14:31.810 and very little leakage very low
00:14:33.660 00:14:33.670 absorption very low ESR and dissipation
00:14:36.090 00:14:36.100 factor all really good characteristics
00:14:38.700 00:14:38.710 for capacitors they're very stable with
00:14:40.980 00:14:40.990 temperature and voltage but they're
00:14:42.960 00:14:42.970 moderately too high price with respect
00:14:44.820 00:14:44.830 to ceramics they're relatively large
00:14:47.580 00:14:47.590 they don't have as good of a volumetric
00:14:49.800 00:14:49.810 efficiency
00:14:50.670 00:14:50.680 you know capacitance per unit volume
00:14:52.560 00:14:52.570 that the aluminum electrolytic or the
00:14:56.570 00:14:56.580 tan alums do but they're also not
00:14:59.190 00:14:59.200 polarized and they're they're going to
00:15:01.740 00:15:01.750 have a you know probably not even as
00:15:03.030 00:15:03.040 good of volumetric efficiency as even
00:15:05.340 00:15:05.350 the multi-layer ceramic caps they are
00:15:08.070 00:15:08.080 available in two kind of broad different
00:15:10.320 00:15:10.330 types there's a metallized film or metal
00:15:13.650 00:15:13.660 foil and film so what's all about film
00:15:17.070 00:15:17.080 capacitors because the what we're
00:15:18.780 00:15:18.790 talking about is the dielectric material
00:15:21.240 00:15:21.250 the the insulator between the two plates
00:15:23.610 00:15:23.620 of the capacitor is some type of a film
00:15:25.850 00:15:25.860 plastic type of a film typically and
00:15:28.530 00:15:28.540 that film can either be metallized on
00:15:31.560 00:15:31.570 one one side and then rolled
00:15:33.620 00:15:33.630 up and that's the metallized film
00:15:34.940 00:15:34.950 capacitors they've got the highest
00:15:36.980 00:15:36.990 density because you don't have a
00:15:38.390 00:15:38.400 separate foil in there where the metal
00:15:40.820 00:15:40.830 and foil film is you've got alternating
00:15:42.890 00:15:42.900 layers of plastic insulator metal foil
00:15:45.620 00:15:45.630 plastic insulator metal foil and that's
00:15:47.600 00:15:47.610 rolled up they generally have lower ESR
00:15:50.420 00:15:50.430 they can operate with higher AC currents
00:15:52.550 00:15:52.560 but they're not going to have as many as
00:15:54.530 00:15:54.540 higher value because they're not as
00:15:57.040 00:15:57.050 it'll get as much capacitance per unit
00:15:59.150 00:15:59.160 density with those that's kind of a
00:16:01.520 00:16:01.530 common characteristics of these film
00:16:03.590 00:16:03.600 caps as I mentioned there are many
00:16:06.440 00:16:06.450 different film types that can be used in
00:16:09.650 00:16:09.660 these film capacitors and they have some
00:16:12.320 00:16:12.330 slightly different characteristics that
00:16:14.300 00:16:14.310 make them useful for certain
00:16:15.500 00:16:15.510 applications the polyester or mylar caps
00:16:19.760 00:16:19.770 are very very common and they're
00:16:22.190 00:16:22.200 moderately stable with temperature you
00:16:23.900 00:16:23.910 know 5 to 15 percent variation over
00:16:25.700 00:16:25.710 temperature they they're pretty good
00:16:28.880 00:16:28.890 with dissipation factor a little bit
00:16:30.380 00:16:30.390 higher than some of the other types but
00:16:33.020 00:16:33.030 they're generally lower cost probably
00:16:35.690 00:16:35.700 the other most common type is a
00:16:37.040 00:16:37.050 polypropylene RPP type caps
00:16:39.790 00:16:39.800 polypropylene z' are very common like
00:16:42.140 00:16:42.150 these orange drop caps and the brown
00:16:43.880 00:16:43.890 drops over here they're generally very
00:16:46.760 00:16:46.770 low absorption they're very stable
00:16:48.410 00:16:48.420 temperature they're just a bit pricier
00:16:50.000 00:16:50.010 than the polyester or mylar caps one of
00:16:53.630 00:16:53.640 the problems though with some of these
00:16:55.010 00:16:55.020 types of caps like a polypropylene
00:16:56.780 00:16:56.790 polyester is that you can't often tell
00:17:00.650 00:17:00.660 from the packaging what type it is you
00:17:03.350 00:17:03.360 can get you know a mylar cap or a
00:17:06.980 00:17:06.990 polypropylene cap that looks like it's
00:17:09.530 00:17:09.540 packaged the same way in these little
00:17:11.059 00:17:11.069 plastic encapsulated packages here you
00:17:13.550 00:17:13.560 know rolled up in these type of axial
00:17:16.130 00:17:16.140 type of devices or dipped in some of
00:17:17.929 00:17:17.939 these others I've seen the polypropylene
00:17:20.960 00:17:20.970 and polyester in both of those package
00:17:22.939 00:17:22.949 styles so you can't always tell by
00:17:24.890 00:17:24.900 looking at them what they are you can be
00:17:26.900 00:17:26.910 pretty sure that it's a film cap but you
00:17:29.930 00:17:29.940 can't necessarily tell what type of film
00:17:31.760 00:17:31.770 they are now some of the other types of
00:17:34.250 00:17:34.260 film is a polystyrene capacitor these
00:17:36.410 00:17:36.420 are really stable with temperature with
00:17:38.240 00:17:38.250 very low dissipation factor and
00:17:40.040 00:17:40.050 absorption a little bit harder to find
00:17:42.230 00:17:42.240 they're pricey I don't have any here
00:17:44.710 00:17:44.720 oftentimes the what these look like they
00:17:47.180 00:17:47.190 look
00:17:47.450 00:17:47.460 almost like a clear tube like a clear
00:17:50.149 00:17:50.159 plastic tube almost like a glass diode
00:17:52.909 00:17:52.919 if you will but it's made of plastic
00:17:54.049 00:17:54.059 with a foil inside of it they're not
00:17:57.620 00:17:57.630 really good in operating in very high
00:18:00.620 00:18:00.630 temperature environments like next to a
00:18:02.240 00:18:02.250 vacuum tube or next to some power
00:18:04.310 00:18:04.320 resistors because the polystyrene
00:18:06.200 00:18:06.210 plastic itself will begin to deform and
00:18:09.230 00:18:09.240 melt but they're but an applications
00:18:11.960 00:18:11.970 where it's low power type applications
00:18:13.669 00:18:13.679 or actually are a pretty superior to
00:18:15.440 00:18:15.450 some of the other films but they are
00:18:17.570 00:18:17.580 harder to find a little bit pricey
00:18:19.899 00:18:19.909 polycarbonate caps very high reliability
00:18:23.000 00:18:23.010 they're also pretty pricey performance
00:18:25.880 00:18:25.890 is about the same as the polypropylene
00:18:27.220 00:18:27.230 there are lots of other different types
00:18:29.480 00:18:29.490 of film caps at different types of films
00:18:32.539 00:18:32.549 that are used and you almost have to
00:18:33.830 00:18:33.840 look up and see what the characteristics
00:18:35.630 00:18:35.640 are but the two most common istra come
00:18:37.850 00:18:37.860 across will be the polypropylene or the
00:18:40.310 00:18:40.320 polyester and with the polypropylene
00:18:43.070 00:18:43.080 generally being the higher performance
00:18:45.230 00:18:45.240 of the two they're really good for high
00:18:47.600 00:18:47.610 voltage applications they're really good
00:18:50.029 00:18:50.039 and stable for temperature and voltage
00:18:51.850 00:18:51.860 they've got pretty low dissipation
00:18:54.289 00:18:54.299 factor and dielectric absorption and
00:18:57.470 00:18:57.480 they're really good from everything from
00:18:58.669 00:18:58.679 audio to RF applications here the
00:19:01.340 00:19:01.350 downsides is is that they're pricey
00:19:02.960 00:19:02.970 they're physically a bit large and
00:19:05.090 00:19:05.100 they're a bit limited in the package
00:19:07.250 00:19:07.260 styles that you can get these film caps
00:19:10.399 00:19:10.409 are often the ones that if you're doing
00:19:11.899 00:19:11.909 some restoration of of old antique
00:19:14.630 00:19:14.640 radios and things like that you're going
00:19:17.090 00:19:17.100 to be replacing some of these early film
00:19:20.180 00:19:20.190 caps these are a little paper and wax
00:19:22.159 00:19:22.169 though so it wasn't really a film that
00:19:24.560 00:19:24.570 with the dielectric was actually a paper
00:19:25.970 00:19:25.980 that was used it was a paper and foil
00:19:27.950 00:19:27.960 wrapped up and then stuffed in the tube
00:19:30.080 00:19:30.090 and sealed with wax these capacitors by
00:19:32.690 00:19:32.700 now are all kind of dried out and leaky
00:19:34.909 00:19:34.919 and all need to be replaced and
00:19:36.560 00:19:36.570 replacing them with you know mylar or
00:19:38.899 00:19:38.909 polypropylene caps is the most common
00:19:41.450 00:19:41.460 thing that you would do in these type
00:19:43.970 00:19:43.980 applications now one other point I'll
00:19:46.730 00:19:46.740 make about these film caps especially
00:19:49.010 00:19:49.020 those that are around you know wound up
00:19:50.990 00:19:51.000 like a coil here is oftentimes you'll
00:19:53.480 00:19:53.490 see they've got a band marking on them
00:19:55.220 00:19:55.230 that would make you think that they're
00:19:56.750 00:19:56.760 polarized well the reality is they're
00:19:58.700 00:19:58.710 not really they're not polarized caps or
00:20:00.529 00:20:00.539 not
00:20:00.799 00:20:00.809 like the tan alumns or the aluminum
00:20:03.350 00:20:03.360 electrolytic s-- what that band
00:20:06.110 00:20:06.120 indicates is which you know terminal on
00:20:09.649 00:20:09.659 the capacitor is connected to the outer
00:20:12.769 00:20:12.779 foil wrapping so if you think about it
00:20:15.049 00:20:15.059 you've got a basically an insulating
00:20:17.690 00:20:17.700 layer and a conductive layer that are
00:20:19.159 00:20:19.169 wrapped up so one of the conductors is
00:20:23.539 00:20:23.549 going to be on the inside of that last
00:20:25.610 00:20:25.620 wrap the other conductors will be on the
00:20:27.710 00:20:27.720 outside that last wrap with the
00:20:29.330 00:20:29.340 insulator being in the middle so the
00:20:31.549 00:20:31.559 band indicates the outer wrapping is
00:20:34.879 00:20:34.889 connected to that wire and oftentimes in
00:20:37.519 00:20:37.529 the electronics we're going to want to
00:20:38.779 00:20:38.789 do is connect that to the lowest
00:20:41.419 00:20:41.429 potential low-voltage potential in the
00:20:44.419 00:20:44.429 circuit so that you don't have a high
00:20:46.190 00:20:46.200 voltage on the outer perimeter up here
00:20:48.919 00:20:48.929 but there may be applications where you
00:20:51.350 00:20:51.360 may choose one end or the other to be
00:20:53.779 00:20:53.789 connected up in a certain part of the
00:20:55.549 00:20:55.559 circuit to prevent coupling you know to
00:20:57.499 00:20:57.509 the to the the capacitor you might want
00:21:01.039 00:21:01.049 to connect the outer foil edge to the
00:21:03.799 00:21:03.809 lowest impedance node in the circuit but
00:21:06.259 00:21:06.269 that's why these film capacitors are
00:21:08.389 00:21:08.399 often marked with a band you'll see them
00:21:10.489 00:21:10.499 like on that and even on this this dip
00:21:12.769 00:21:12.779 variety you've got the band marked here
00:21:14.600 00:21:14.610 that means that this lead here is
00:21:16.489 00:21:16.499 connected to the outer foil wrapping of
00:21:18.859 00:21:18.869 the capacitor inside this molded case
00:21:21.460 00:21:21.470 the next type of capacitor we'll talk
00:21:23.690 00:21:23.700 about our mica capacitors with the
00:21:26.060 00:21:26.070 dielectric material is actually a mica
00:21:28.249 00:21:28.259 of material some of the older ones were
00:21:30.649 00:21:30.659 in these were called Domino packages and
00:21:32.899 00:21:32.909 typically have these colored dots that
00:21:34.430 00:21:34.440 would indicate though what they the
00:21:35.989 00:21:35.999 value is another typically in these kind
00:21:38.659 00:21:38.669 of molded packages again typically
00:21:41.180 00:21:41.190 relatively low value you know a
00:21:42.889 00:21:42.899 picofarad to maybe 10 nano flowers or so
00:21:45.320 00:21:45.330 but can operate at very high voltages
00:21:47.330 00:21:47.340 mica caps are really stable with
00:21:50.149 00:21:50.159 temperature really stable with voltage
00:21:52.129 00:21:52.139 they're available in very tight
00:21:53.869 00:21:53.879 tolerances not these particular devices
00:21:55.549 00:21:55.559 but they are available in some very
00:21:57.350 00:21:57.360 tight tolerances and they got really
00:21:59.299 00:21:59.309 good RF performance that the dissipation
00:22:02.119 00:22:02.129 factor is very low are very very
00:22:04.340 00:22:04.350 commonly used in RF applications and
00:22:06.889 00:22:06.899 filters and voltage controlled
00:22:08.539 00:22:08.549 oscillators or other oscillator of
00:22:10.759 00:22:10.769 frequency generation circuits
00:22:13.220 00:22:13.230 very common places to have mica cats
00:22:14.840 00:22:14.850 because they're very very stable the bad
00:22:17.450 00:22:17.460 thing is that they're smaller values
00:22:18.799 00:22:18.809 they're limited and package styles and
00:22:21.200 00:22:21.210 things like that now we use you might
00:22:23.990 00:22:24.000 say these look an awful lot like those
00:22:25.460 00:22:25.470 molded film caps now the way you can
00:22:29.270 00:22:29.280 generally tell the my caps apart is that
00:22:31.430 00:22:31.440 they're a bit lumpy if I if you will if
00:22:34.100 00:22:34.110 you'll take a look at this package it's
00:22:35.900 00:22:35.910 kind of bulged at the ends or maybe
00:22:38.480 00:22:38.490 almost a little bit dog bone shaped you
00:22:40.490 00:22:40.500 know if you can think about it that way
00:22:41.810 00:22:41.820 in terms of the way the package is
00:22:43.310 00:22:43.320 compared to the film caps which are
00:22:45.530 00:22:45.540 generally a bit more smooth and with pay
00:22:49.490 00:22:49.500 you know cylindrical or just don't have
00:22:51.830 00:22:51.840 the lumpiness especially associated at
00:22:53.690 00:22:53.700 the ends that's almost you know the only
00:22:55.880 00:22:55.890 way you can kind of really tell whether
00:22:58.070 00:22:58.080 that's a mica capacitor or a film cap
00:23:01.190 00:23:01.200 because the the molded caps kind of look
00:23:03.770 00:23:03.780 the same but generally if it's kind of a
00:23:06.200 00:23:06.210 lumpy kind of a package that would
00:23:08.240 00:23:08.250 almost tell you that it's a mica
00:23:09.380 00:23:09.390 capacitor and also you can often tell
00:23:11.570 00:23:11.580 from the application if it's in an RF
00:23:14.390 00:23:14.400 circuit a VCO or something like that
00:23:16.250 00:23:16.260 if a mica cap was available it likely
00:23:19.039 00:23:19.049 would have been used in that application
00:23:21.220 00:23:21.230 now of course there are lots of
00:23:23.240 00:23:23.250 varieties of variable capacitors as well
00:23:25.700 00:23:25.710 some of these larger and air dielectric
00:23:28.310 00:23:28.320 kind of bread slicer variable caps and
00:23:31.210 00:23:31.220 smaller called poly very cons because
00:23:34.370 00:23:34.380 they like a poly film variable capacitor
00:23:37.909 00:23:37.919 typically got some trimmers as well as
00:23:40.039 00:23:40.049 kind of main tuning on them find these
00:23:42.560 00:23:42.570 in some of the older transistor radios
00:23:44.810 00:23:44.820 might find some of these in some of the
00:23:46.490 00:23:46.500 older larger transistor radios or
00:23:49.070 00:23:49.080 tabletop or even tube radios and things
00:23:51.350 00:23:51.360 like that to make the tune local
00:23:54.650 00:23:54.660 oscillators for tuning the radio around
00:23:57.130 00:23:57.140 there you'll also have tremor capacitors
00:23:59.750 00:23:59.760 that might be small little ceramic type
00:24:03.080 00:24:03.090 trimmer caps I've got a bag full of
00:24:04.669 00:24:04.679 different types here maybe some
00:24:06.980 00:24:06.990 compression caps these these guys are
00:24:09.620 00:24:09.630 basically two plates that when you
00:24:11.539 00:24:11.549 loosen the screw the plates separate and
00:24:13.909 00:24:13.919 they'll often have a mica insulator
00:24:15.500 00:24:15.510 between them these types of caps
00:24:18.140 00:24:18.150 obviously all used in RF applications
00:24:20.049 00:24:20.059 here's kind of a slug tuned variable cap
00:24:23.930 00:24:23.940 here as well lots of different types of
00:24:26.510 00:24:26.520 very
00:24:27.020 00:24:27.030 capacitors that you'll run across but in
00:24:30.110 00:24:30.120 general all of these are typically used
00:24:32.540 00:24:32.550 for
00:24:33.830 00:24:33.840 you know RF applications where devices
00:24:36.590 00:24:36.600 like these - designed to be kind of
00:24:38.540 00:24:38.550 tuned and operated all the time where
00:24:40.910 00:24:40.920 the trimmers are typically you know set
00:24:43.250 00:24:43.260 and adjusted you know to tune or align a
00:24:45.440 00:24:45.450 circuit and then they're if they're left
00:24:46.910 00:24:46.920 alone and never adjust it again so if
00:24:48.710 00:24:48.720 they don't have the durability of some
00:24:50.720 00:24:50.730 of these continuously variable devices
00:24:54.100 00:24:54.110 of course really kind of impossible to
00:24:56.750 00:24:56.760 cover all the different types of
00:24:58.340 00:24:58.350 capacitors and all the specific
00:25:00.080 00:25:00.090 applications and characteristics in one
00:25:02.600 00:25:02.610 short video but I hope this this brief
00:25:05.210 00:25:05.220 introduction to the different types of
00:25:07.100 00:25:07.110 capacitors their characteristics and
00:25:10.190 00:25:10.200 their basic applications and where
00:25:12.110 00:25:12.120 you'll find them was been helpful and
00:25:13.730 00:25:13.740 again just remember that the vast
00:25:16.010 00:25:16.020 majority of the polarized caps that you
00:25:18.650 00:25:18.660 see will be a luminal aluminum
00:25:20.540 00:25:20.550 electrolytic or possibly tantalum and
00:25:22.820 00:25:22.830 the vast majority of the non polarized
00:25:25.760 00:25:25.770 capacitors you see in a design are most
00:25:28.010 00:25:28.020 likely ceramic whereas you could use
00:25:31.880 00:25:31.890 film capacitors or even you know mica
00:25:35.090 00:25:35.100 capacitors in those applications
00:25:37.340 00:25:37.350 particularly if you're operating it at
00:25:40.010 00:25:40.020 over a wide temperature range or at
00:25:42.830 00:25:42.840 higher frequency so I hope it's been
00:25:44.870 00:25:44.880 helpful if you like what you see give me
00:25:47.060 00:25:47.070 a thumbs up if you haven't subscribed
00:25:49.100 00:25:49.110 already please do so and we'll see you
00:25:51.500 00:25:51.510 again next time
00:25:52.220 00:25:52.230 thanks for watching
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