Are Your Capacitors Installed Backwards Build this and find out

WEBVTT
Kind: captions
Language: en

00:00:07.810
hi there if you're into restoring old
00:00:10.620 00:00:10.630 receivers or older
00:00:13.820 00:00:13.830 or even building amplifiers problem
00:00:16.080 00:00:16.090 we find this information rather
00:00:17.130 00:00:17.140 interesting so those orange dip brown
00:00:19.950 00:00:19.960 dip green dip and those little yellow
00:00:21.420 00:00:21.430 axial lead capacitors and many more
00:00:23.700 00:00:23.710 capacitors have a polarity in circuit
00:00:25.980 00:00:25.990 and should be installed in the circuit
00:00:27.450 00:00:27.460 the correct way in order for them not to
00:00:29.760 00:00:29.770 pick up hum from adjacent parts of your
00:00:32.220 00:00:32.230 amplifier or radio or to pick up
00:00:34.320 00:00:34.330 interference from adjacent parts of the
00:00:36.119 00:00:36.129 chassis whatever they're installed into
00:00:38.119 00:00:38.129 so in this video what we're going to do
00:00:40.410 00:00:40.420 is we're going to discuss why these
00:00:42.180 00:00:42.190 capacitors have a polarity and then
00:00:44.610 00:00:44.620 we're going to build a little circuit
00:00:45.900 00:00:45.910 that will help us locate this polarity
00:00:47.670 00:00:47.680 quickly we all know that if you're
00:00:50.010 00:00:50.020 restoring a radio or an old guitar
00:00:51.330 00:00:51.340 amplifier they usually have a handful of
00:00:52.860 00:00:52.870 capacitors in them and you really don't
00:00:54.750 00:00:54.760 want to be doing this while you're
00:00:55.889 00:00:55.899 restoring the receiver or amplifier so
00:00:58.590 00:00:58.600 00:00:59.430 00:00:59.440 that will help you grade them with an
00:01:00.959 00:01:00.969 oscilloscope very quickly and then you
00:01:02.610 00:01:02.620 with a little felt marker you can mark
00:01:04.320 00:01:04.330 the band end or as it was called in the
00:01:06.900 00:01:06.910 old days the outside foil end of the
00:01:09.270 00:01:09.280 capacitor so let's get into the video
00:01:11.609 00:01:11.619 and start discussing why these
00:01:13.469 00:01:13.479 capacitors actually have a polarity here
00:01:16.950 00:01:16.960 we have two very common circuits that
00:01:19.080 00:01:19.090 you'll find in a lot of vacuum tube gear
00:01:20.790 00:01:20.800 this upper circuit here you'll notice is
00:01:23.040 00:01:23.050 in a lot of guitar amplifiers or high
00:01:24.930 00:01:24.940 fidelity amplifiers or stereo receivers
00:01:27.300 00:01:27.310 this really is just an audio
00:01:29.340 00:01:29.350 amplification chain here this bottom
00:01:32.130 00:01:32.140 portion of the schematic I've kind of
00:01:33.480 00:01:33.490 drawn to represent either an if'
00:01:35.339 00:01:35.349 amplifier or an audio amplifier of
00:01:37.350 00:01:37.360 course we'd have to amend this
00:01:38.850 00:01:38.860 transformer to represent either/or but
00:01:40.800 00:01:40.810 we're not going to get too crazy about
00:01:42.270 00:01:42.280 that right now because it's all about
00:01:43.889 00:01:43.899 just learning which way we need to
00:01:45.540 00:01:45.550 install our new capacitors in this
00:01:47.430 00:01:47.440 circuit for the best circuit performance
00:01:49.529 00:01:49.539 and the least amount of interference so
00:01:53.279 00:01:53.289 way back in the day they used to make
00:01:55.199 00:01:55.209 capacitors that looked like this and if
00:01:58.529 00:01:58.539 you ever find a capacitor like this in
00:02:00.270 00:02:00.280 any kind of gear that you're working on
00:02:02.460 00:02:02.470 it has to go these are all faulty by now
00:02:05.249 00:02:05.259 and they leak now when I talk about
00:02:08.490 00:02:08.500 leaking I don't mean that they leak
00:02:10.380 00:02:10.390 physically they're not leaking a
00:02:11.880 00:02:11.890 substance like oil or goop out of them
00:02:13.860 00:02:13.870 they leak DC across them so whenever you
00:02:17.010 00:02:17.020 hear the term leaky capacitor that means
00:02:19.530 00:02:19.540 that they're leaking direct current
00:02:21.479 00:02:21.489 through them capacitors are supposed to
00:02:23.430 00:02:23.440 block DC and pass alternating current
00:02:26.190 00:02:26.200 through them so when they leak that
00:02:28.319 00:02:28.329 means that this capacitor
00:02:29.790 00:02:29.800 effectively turning into a resistor and
00:02:31.830 00:02:31.840 that is no good for the next stage so
00:02:34.980 00:02:34.990 what happens in these capacitors is
00:02:36.900 00:02:36.910 they've got paper inside of them that's
00:02:38.970 00:02:38.980 gone acidic and it's basically dis
00:02:41.610 00:02:41.620 turning into a big resistor rate now and
00:02:43.860 00:02:43.870 when these capacitors turn into
00:02:45.780 00:02:45.790 resistors they bias up the next stage
00:02:47.760 00:02:47.770 and cause the tube over here to draw
00:02:49.830 00:02:49.840 heavy current it causes damage to the
00:02:51.690 00:02:51.700 circuit you burn out plate resistors and
00:02:53.580 00:02:53.590 AF transformers and it does all sorts of
00:02:55.770 00:02:55.780 bad things so you want to get rid of
00:02:57.810 00:02:57.820 these capacitors and replace them with a
00:02:59.460 00:02:59.470 modern equivalent like a an orange dip
00:03:01.860 00:03:01.870 or a brown dip and I'll grab one of
00:03:03.720 00:03:03.730 those here in just a minute to show you
00:03:05.210 00:03:05.220 so back in the day when these were brand
00:03:07.440 00:03:07.450 new they're great capacitors they didn't
00:03:08.940 00:03:08.950 leak or anything and they were nice
00:03:10.800 00:03:10.810 enough to mark the outside foil
00:03:12.780 00:03:12.790 end of the capacitor by putting a band
00:03:14.670 00:03:14.680 on it and printing outside foil on it
00:03:16.710 00:03:16.720 now the outside foil and means that this
00:03:20.310 00:03:20.320 lead on the capacitor comes into here
00:03:23.370 00:03:23.380 and it also attaches to an outside foil
00:03:25.620 00:03:25.630 jacket that's just great underneath this
00:03:28.560 00:03:28.570 paper here and it shields the entire
00:03:30.270 00:03:30.280 capacitor so if we were to tie this to
00:03:32.970 00:03:32.980 the chassis this whole capacitor would
00:03:34.710 00:03:34.720 be shielded right up to this point right
00:03:36.449 00:03:36.459 to where this lead goes in this lead
00:03:38.460 00:03:38.470 goes it to the inside layers so in
00:03:41.310 00:03:41.320 effect these capacitors actually do have
00:03:43.410 00:03:43.420 a polarity now so do a lot of the modern
00:03:46.650 00:03:46.660 capacitors and if they're built
00:03:48.540 00:03:48.550 correctly they'll actually be made with
00:03:50.640 00:03:50.650 you know metallized polypropylene or you
00:03:53.220 00:03:53.230 know PVC or whatever they're building
00:03:55.350 00:03:55.360 their new capacitors with and of course
00:03:56.910 00:03:56.920 whichever new style capacitor that you
00:03:59.010 00:03:59.020 end up buying they will have an outside
00:04:01.740 00:04:01.750 foil jacket connected to one end it's
00:04:04.020 00:04:04.030 just that they didn't spend the time to
00:04:06.330 00:04:06.340 actually mark it and that's what we're
00:04:08.430 00:04:08.440 going to do in this video is we're going
00:04:10.050 00:04:10.060 to locate that odor odor foil or the
00:04:12.780 00:04:12.790 outer metallized polypropylene layer so
00:04:15.479 00:04:15.489 that when you install your capacitors
00:04:17.039 00:04:17.049 into circuit you're going to pick up
00:04:19.020 00:04:19.030 less hum and a less adjacent
00:04:21.210 00:04:21.220 interference and you know either you're
00:04:23.850 00:04:23.860 not going to get oscillation because you
00:04:25.320 00:04:25.330 have a really large exposed surface
00:04:27.570 00:04:27.580 hooked to a high impedance portion of
00:04:29.700 00:04:29.710 your circuit so now these capacitors
00:04:33.150 00:04:33.160 we'll just use this as an example for a
00:04:35.220 00:04:35.230 modern capacitor so say this was a
00:04:37.310 00:04:37.320 brand-new modern capacitor okay if we
00:04:40.620 00:04:40.630 were to install this into the circuit
00:04:43.260 00:04:43.270 this end here would go to the lower
00:04:44.940 00:04:44.950 impedance point always so this end here
00:04:48.030 00:04:48.040 with the end with the band if we were to
00:04:49.920 00:04:49.930 use this as an RF bypassing capacitor
00:04:52.350 00:04:52.360 would always go to the chassis and this
00:04:54.600 00:04:54.610 would go to the the grid of the tubes
00:04:56.820 00:04:56.830 say the screen grid if we wanted to keep
00:04:58.500 00:04:58.510 RF off the screen grid or something like
00:05:00.270 00:05:00.280 that it would go like this because when
00:05:02.280 00:05:02.290 we tie this end of the chassis
00:05:03.810 00:05:03.820 this entire capacitor is shielded right
00:05:06.300 00:05:06.310 up to this point now if we hook this up
00:05:08.550 00:05:08.560 in Reverse and say we tied this end of
00:05:10.800 00:05:10.810 the chassis and this end of the tube
00:05:12.210 00:05:12.220 socket we'd have all of this area that
00:05:14.430 00:05:14.440 is completely exposed right up to this
00:05:16.830 00:05:16.840 point so of course we don't want to have
00:05:19.320 00:05:19.330 that because that's more exposed area
00:05:21.090 00:05:21.100 and of course we're going to pick up
00:05:22.590 00:05:22.600 more interference that way especially if
00:05:24.870 00:05:24.880 we have a filament or a heater line
00:05:26.940 00:05:26.950 running past this that's that's
00:05:29.070 00:05:29.080 definitely no good we definitely want
00:05:31.290 00:05:31.300 this end to the chassis side now when
00:05:34.950 00:05:34.960 we're hooking this up to a standard
00:05:36.390 00:05:36.400 audio amplification circuit here this
00:05:38.390 00:05:38.400 capacitor would go in this way because
00:05:40.470 00:05:40.480 the band end or the outside foil and
00:05:42.750 00:05:42.760 always goes to the lower impedance
00:05:44.220 00:05:44.230 portion of the circuit and the lower
00:05:46.410 00:05:46.420 impedance portion of the circuit most of
00:05:49.140 00:05:49.150 the time is the plate of the preceding
00:05:51.630 00:05:51.640 stage here or the earlier stage I should
00:05:53.940 00:05:53.950 say so this band end will always go
00:05:57.900 00:05:57.910 towards the plate and this end always
00:05:59.790 00:05:59.800 goes towards the grid in this particular
00:06:02.040 00:06:02.050 circuit and in this capacitor would be
00:06:04.110 00:06:04.120 the same way and if we had a capacitor
00:06:05.880 00:06:05.890 on the input here it would be the exact
00:06:07.830 00:06:07.840 same way again on this bottom circuit
00:06:11.700 00:06:11.710 here
00:06:12.060 00:06:12.070 we'll notice that there is a capacitor
00:06:13.470 00:06:13.480 missing on the screen grid and this
00:06:15.420 00:06:15.430 would be considered an RF bypass
00:06:17.310 00:06:17.320 capacitor we want to keep RF off the
00:06:19.260 00:06:19.270 screen grid here because we don't want
00:06:21.060 00:06:21.070 this screen grid to amplify any kind of
00:06:22.920 00:06:22.930 oscillations or any kind of interference
00:06:24.780 00:06:24.790 that's in the chassis so by mounting
00:06:27.960 00:06:27.970 this capacitor in we would have to mount
00:06:29.880 00:06:29.890 the band end to the ground or the
00:06:31.800 00:06:31.810 chassis and that would tie to the screen
00:06:34.500 00:06:34.510 grid now of course we don't want a lot
00:06:36.420 00:06:36.430 of lead inductance there so we want to
00:06:38.430 00:06:38.440 keep the lead as short as possible but
00:06:40.800 00:06:40.810 again you have to use some common sense
00:06:42.810 00:06:42.820 you don't want an extremely short lead
00:06:44.460 00:06:44.470 so that when you're soldering it if you
00:06:46.500 00:06:46.510 have a newer capacitor you're going to
00:06:48.090 00:06:48.100 melt the poly the metallized
00:06:49.800 00:06:49.810 polypropylene with the heat of your
00:06:51.210 00:06:51.220 soldering iron you'll probably need to
00:06:53.190 00:06:53.200 leave a little bit of lead so that it'll
00:06:54.750 00:06:54.760 dissipate some heat
00:06:56.010 00:06:56.020 so again these capacitors need to go in
00:06:59.370 00:06:59.380 like this and they need to go in like
00:07:01.350 00:07:01.360 this and they need to go in like this
00:07:03.810 00:07:03.820 okay so depending on what stage or what
00:07:07.020 00:07:07.030 what kind of schematic you've got going
00:07:09.180 00:07:09.190 on so now we have new capacitors that
00:07:13.380 00:07:13.390 look like this right here you can see
00:07:15.570 00:07:15.580 this this has no markings on it and when
00:07:17.730 00:07:17.740 these capacitors are created they're
00:07:19.590 00:07:19.600 going down the assembly line this way
00:07:21.360 00:07:21.370 and then they get the the writing or the
00:07:23.550 00:07:23.560 printing on them this way or they'll get
00:07:25.770 00:07:25.780 them on this way because it really
00:07:27.390 00:07:27.400 doesn't matter they're in a machine that
00:07:28.830 00:07:28.840 doesn't really pick which way they go
00:07:30.150 00:07:30.160 down the line so they could be any old
00:07:32.910 00:07:32.920 way and we need to find out which end
00:07:35.360 00:07:35.370 which lead is attached to the outermost
00:07:38.570 00:07:38.580 metallized polypropylene or we could
00:07:41.550 00:07:41.560 call it the the actual shielding inside
00:07:43.890 00:07:43.900 the capacitor which would be the outer
00:07:45.930 00:07:45.940 the outer layer them outermost layer of
00:07:48.720 00:07:48.730 this capacitor and that's very important
00:07:51.180 00:07:51.190 so that we install this into the circuit
00:07:53.190 00:07:53.200 the correct way because we don't know
00:07:55.380 00:07:55.390 now a lot of people think that when they
00:07:58.110 00:07:58.120 buy these orange dip capacitors that oh
00:08:00.270 00:08:00.280 look they've been really nice and
00:08:01.980 00:08:01.990 they've marked that well really have
00:08:05.220 00:08:05.230 they this is how you test for the
00:08:08.880 00:08:08.890 outside shielded end of your capacitor
00:08:11.040 00:08:11.050 or the outside foil and or outside
00:08:13.110 00:08:13.120 metallized polypropylene layer however
00:08:15.150 00:08:15.160 you want to call it we're really just
00:08:16.740 00:08:16.750 looking for the shielded end of your
00:08:18.900 00:08:18.910 capacitor and this is how you find it
00:08:21.060 00:08:21.070 using an oscilloscope and a very simple
00:08:23.280 00:08:23.290 little setup like this which is
00:08:24.750 00:08:24.760 basically just a BNC cable with the
00:08:26.430 00:08:26.440 center conductor attached to an
00:08:27.930 00:08:27.940 alligator clip and the shield is also
00:08:30.090 00:08:30.100 attached to an alligator clip I have
00:08:31.500 00:08:31.510 them right now just clip together to
00:08:33.000 00:08:33.010 keep the noise off the screen so if you
00:08:36.090 00:08:36.100 have a newer modern DSO that goes down
00:08:37.800 00:08:37.810 to about 5 millivolts per division you
00:08:39.690 00:08:39.700 should be absolutely fine
00:08:41.370 00:08:41.380 right now this is running at 2
00:08:43.020 00:08:43.030 millivolts per division and you know
00:08:45.270 00:08:45.280 we're not going to get too accurate with
00:08:46.620 00:08:46.630 the readings because really I'm just
00:08:47.970 00:08:47.980 acting as a random hum antenna in order
00:08:50.370 00:08:50.380 to determine the outside foil end of
00:08:53.280 00:08:53.290 these capacitors and I'll explain that
00:08:55.140 00:08:55.150 here quite shortly so the first
00:08:57.300 00:08:57.310 capacitor we're going to look at is this
00:08:58.920 00:08:58.930 old wax capacitor now we wouldn't want
00:09:01.320 00:09:01.330 to use this in circuit because this
00:09:02.820 00:09:02.830 capacitor is well past its due date but
00:09:04.920 00:09:04.930 we're really just looking at a shielding
00:09:07.500 00:09:07.510 aspect of this capacitor so this will be
00:09:09.540 00:09:09.550 just fine for this test so what I'm
00:09:12.150 00:09:12.160 going to do is I'll hook this into
00:09:13.500 00:09:13.510 circuit the correct way and we'll look
00:09:15.210 00:09:15.220 at the signal on the screen and the
00:09:16.800 00:09:16.810 amplitude here and then we'll reverse
00:09:18.750 00:09:18.760 this capacitor and see the differences
00:09:21.079 00:09:21.089 so right now I'm disconnecting this
00:09:23.940 00:09:23.950 thing up and this is the way that it
00:09:25.410 00:09:25.420 should normally be I'm acting as the hum
00:09:27.269 00:09:27.279 antenna right now I'm holding the the
00:09:29.910 00:09:29.920 case of the capacitor right now so you
00:09:31.920 00:09:31.930 could look at me as a very nearby heater
00:09:35.069 00:09:35.079 line running past this capacitor and in
00:09:37.949 00:09:37.959 a chassis or something like that so
00:09:41.130 00:09:41.140 that's the amplitude that we got with it
00:09:42.660 00:09:42.670 hooked up the correct way you can see
00:09:44.190 00:09:44.200 the banded end is connected to the
00:09:45.960 00:09:45.970 outside shield of the cable this is the
00:09:48.150 00:09:48.160 lower impedance portion of the circuit
00:09:50.310 00:09:50.320 this would be the chassis and we're
00:09:52.620 00:09:52.630 always looking for the lowest amplitude
00:09:55.230 00:09:55.240 when we have found the lowest amplitude
00:09:57.210 00:09:57.220 we have the capacitor hooked up the
00:09:59.430 00:09:59.440 correct way when the amplitudes high
00:10:01.470 00:10:01.480 it's hooked up backwards so what I'll do
00:10:03.930 00:10:03.940 is I'll hook this one up the other way
00:10:06.440 00:10:06.450 and we can tell that we have this hooked
00:10:10.620 00:10:10.630 up backwards because now the outside
00:10:12.990 00:10:13.000 foil which is the the shielding on this
00:10:15.900 00:10:15.910 capacitor is capacitively coupled to me
00:10:18.389 00:10:18.399 and I'm feeding signal into my
00:10:20.220 00:10:20.230 oscilloscope so that we can see here
00:10:22.290 00:10:22.300 very simply that this capacitor is now
00:10:24.630 00:10:24.640 hooked up backwards remember we're
00:10:26.310 00:10:26.320 00:10:29.250 00:10:29.260 and then we know when the negative or
00:10:31.949 00:10:31.959 the common lead of our oscilloscope is
00:10:33.900 00:10:33.910 hooked to that and when we have the
00:10:35.610 00:10:35.620 lowest amplitude that is the end that we
00:10:37.800 00:10:37.810 will mark as the outside shielded end or
00:10:40.470 00:10:40.480 the outside foil under whatever you want
00:10:42.600 00:10:42.610 to call it so that's this capacitor here
00:10:45.990 00:10:46.000 so let's grab a newer orange dip
00:10:47.910 00:10:47.920 capacitor and take a look at it so
00:10:50.880 00:10:50.890 here's a newer orange dip capacitor and
00:10:52.829 00:10:52.839 we have a line here and we might think
00:10:55.889 00:10:55.899 that oh that line indicates the outside
00:10:58.500 00:10:58.510 foil and well let's test that out I'll
00:11:00.689 00:11:00.699 just hook the capacitor up to it right
00:11:02.430 00:11:02.440 now it's much easier to hook this up off
00:11:05.100 00:11:05.110 of screen here so there we go
00:11:08.040 00:11:08.050 so now I've got this outside shield of
00:11:12.420 00:11:12.430 my braid hooked up to this and this
00:11:13.949 00:11:13.959 would be considered the chassis and this
00:11:16.050 00:11:16.060 here would be considered the part that
00:11:18.300 00:11:18.310 goes into the higher impedance portion
00:11:20.579 00:11:20.589 of the circuit okay so now what I'll do
00:11:23.160 00:11:23.170 is
00:11:23.519 00:11:23.529 flip these leads around now if I flip
00:11:26.040 00:11:26.050 these leads around and the amplitude
00:11:27.869 00:11:27.879 goes down that means that this side is
00:11:31.319 00:11:31.329 not the outside foil and remember the
00:11:34.650 00:11:34.660 side that the shielding is on is always
00:11:37.920 00:11:37.930 when the amplitude is lower is the
00:11:39.780 00:11:39.790 outside foil and so what I'll do is I'll
00:11:42.269 00:11:42.279 reverse these leads right now and look
00:11:48.540 00:11:48.550 at that we have lower amplitude here so
00:11:51.449 00:11:51.459 this line here does not denote the
00:11:54.329 00:11:54.339 outside foil and this side here is the
00:11:57.869 00:11:57.879 shielded end of this capacitor so again
00:12:02.519 00:12:02.529 I'll hook this back into circuit the
00:12:06.509 00:12:06.519 other way and we can see that we have
00:12:08.759 00:12:08.769 more amplitude this way and then if I
00:12:12.119 00:12:12.129 change these around and see that there's
00:12:18.679 00:12:18.689 almost nothing there so this side here
00:12:22.290 00:12:22.300 would be the side that we would want to
00:12:24.989 00:12:24.999 connect to the chassis we would mark
00:12:26.579 00:12:26.589 this side here with a line as the
00:12:28.769 00:12:28.779 outside foil okay
00:12:31.439 00:12:31.449 so let's grab another orange dip
00:12:34.199 00:12:34.209 capacitor right here and test it out the
00:12:36.840 00:12:36.850 same way so I'll hook this up the way
00:12:39.210 00:12:39.220 that we would think that it's hooked up
00:12:40.740 00:12:40.750 this is the band end here so we'd figure
00:12:43.079 00:12:43.089 that that is the outside foil alright so
00:12:47.220 00:12:47.230 now what I'll do is I'll reverse the
00:12:48.569 00:12:48.579 leads and we can clearly see with this
00:12:55.619 00:12:55.629 capacitor that this side here is
00:12:57.720 00:12:57.730 definitely not the outside foil or the
00:13:00.240 00:13:00.250 outside metallized polypropylene or
00:13:02.220 00:13:02.230 whatever metallized PVC this here this
00:13:05.460 00:13:05.470 side is so this here would be considered
00:13:08.939 00:13:08.949 the shielded end of the capacitor this
00:13:10.650 00:13:10.660 is the side that would attach to the
00:13:12.329 00:13:12.339 chassis
00:13:13.189 00:13:13.199 again I'll reverse this
00:13:18.730 00:13:18.740 and you can very clearly see that this
00:13:22.030 00:13:22.040 is not the shielded end so let's test an
00:13:28.240 00:13:28.250 older capacitor here I have an older
00:13:30.040 00:13:30.050 kind of a burgundy dip I don't know what
00:13:31.990 00:13:32.000 you would call this but let's consider
00:13:34.420 00:13:34.430 the line end on this one as the outside
00:13:37.720 00:13:37.730 foil so I'll just hook this one up now
00:13:43.080 00:13:43.090 okay so here we go alright you see the
00:13:48.730 00:13:48.740 line is on this end and we have the
00:13:50.200 00:13:50.210 common or the negative lead hooked up
00:13:52.030 00:13:52.040 here alright now I'll reverse the leads
00:13:54.610 00:13:54.620 and we can see on this capacitor that
00:14:01.720 00:14:01.730 line does denote the outside shielded
00:14:05.020 00:14:05.030 end of the capacitor so on this
00:14:07.750 00:14:07.760 capacitor you could regard this line as
00:14:10.480 00:14:10.490 correct now whether these capacitors are
00:14:13.090 00:14:13.100 going down the run like this and they're
00:14:14.530 00:14:14.540 going down the run like this we don't
00:14:15.970 00:14:15.980 really know because I don't have more of
00:14:17.470 00:14:17.480 these to test but it just so happens on
00:14:19.570 00:14:19.580 this capacitor that this and here is the
00:14:22.240 00:14:22.250 shielded end okay so let's take a look
00:14:27.070 00:14:27.080 at this old general Instruments
00:14:29.560 00:14:29.570 capacitor alright and let's test it out
00:14:31.840 00:14:31.850 and see if this band end is the outside
00:14:34.810 00:14:34.820 foil so I'll hook this one up the way we
00:14:37.360 00:14:37.370 would think it would be hooked up
00:14:38.470 00:14:38.480 properly again we have the band end
00:14:42.250 00:14:42.260 hooked to the ground or the common this
00:14:44.860 00:14:44.870 would be considered the chassis okay now
00:14:48.910 00:14:48.920 I'll reverse it
00:14:56.000 00:14:56.010 and we can clearly see that this is not
00:15:00.110 00:15:00.120 the outside foil and on this capacitor
00:15:02.480 00:15:02.490 either
00:15:03.020 00:15:03.030 so really the bands on the ends really
00:15:06.140 00:15:06.150 can be considered either way with a lot
00:15:08.270 00:15:08.280 of these capacitors so really you need
00:15:11.060 00:15:11.070 to test them in order to really know
00:15:12.770 00:15:12.780 what side is the outside foil and you
00:15:15.320 00:15:15.330 can verily very clearly see that there
00:15:18.230 00:15:18.240 is a polarity to these capacitors so
00:15:23.420 00:15:23.430 I'll grab one of my my Brown dip ones
00:15:26.150 00:15:26.160 here all right and I'll hold this one
00:15:29.300 00:15:29.310 this one has absolutely no markings on
00:15:31.340 00:15:31.350 it so we'll test this one out here and
00:15:35.090 00:15:35.100 see this one here okay and I'll reverse
00:15:38.480 00:15:38.490 the leads
00:15:46.690 00:15:46.700 it's just shorting here got these leads
00:15:48.790 00:15:48.800 I'll twist it up there we go so we can
00:15:51.790 00:15:51.800 clearly see that this end here is the
00:15:54.490 00:15:54.500 band end right here even though there
00:15:57.370 00:15:57.380 are no markings on this capacitor so you
00:15:59.950 00:15:59.960 can see the difference is there there's
00:16:01.270 00:16:01.280 the lower amplitude this way and I'll
00:16:03.040 00:16:03.050 reverse the leads and we can see that we
00:16:08.740 00:16:08.750 have higher amplitude this way so this
00:16:14.050 00:16:14.060 end here is the shielded end so now what
00:16:17.800 00:16:17.810 we want to do is since we're going to be
00:16:19.420 00:16:19.430 testing these things you know we're
00:16:21.310 00:16:21.320 going to you know if you're replacing a
00:16:22.810 00:16:22.820 whole lot of these things in a radio
00:16:24.220 00:16:24.230 you're going to be you know basically
00:16:26.170 00:16:26.180 have a small bag full of these things so
00:16:28.510 00:16:28.520 you don't want to be doing this as
00:16:29.860 00:16:29.870 you're you know putting these things in
00:16:31.690 00:16:31.700 the radio you kind of want to pre grade
00:16:33.160 00:16:33.170 these things and find out which end
00:16:34.660 00:16:34.670 really is the Bandon so that you do
00:16:36.370 00:16:36.380 install these things correctly to short
00:16:38.890 00:16:38.900 these leads out here so so what we're
00:16:41.770 00:16:41.780 going to do is create a small circuit
00:16:43.180 00:16:43.190 that does this a little bit easier for
00:16:44.920 00:16:44.930 us and we'll check out maybe a couple of
00:16:48.280 00:16:48.290 different ideas and see what we can
00:16:49.950 00:16:49.960 design here and make a little make a
00:16:52.900 00:16:52.910 little test jig for these things before
00:16:55.930 00:16:55.940 I start building a small project I
00:16:57.610 00:16:57.620 usually like to check my own stock and
00:16:59.680 00:16:59.690 see if I have enough parts and pieces to
00:17:01.750 00:17:01.760 make this with the with the parts that I
00:17:03.520 00:17:03.530 have on hand so I would like to build
00:17:07.060 00:17:07.070 this into a smaller project box and it
00:17:09.550 00:17:09.560 just so happens that I have another one
00:17:10.930 00:17:10.940 around
00:17:11.500 00:17:11.510 I built the TDR out of the same one I
00:17:13.360 00:17:13.370 can't find the other project box I put
00:17:16.060 00:17:16.070 it in a very safe place so that I would
00:17:18.190 00:17:18.200 find it the next time as I can as I can
00:17:20.920 00:17:20.930 now see so anyways I'll locate this
00:17:22.840 00:17:22.850 other project box it looks just like
00:17:24.160 00:17:24.170 this one here except of course there's
00:17:26.470 00:17:26.480 nothing in it it's just a solid you know
00:17:28.420 00:17:28.430 cast box here so I'll end up using this
00:17:31.480 00:17:31.490 box here and the reason I want to use
00:17:33.670 00:17:33.680 this box over a plastic box is this is
00:17:36.670 00:17:36.680 completely shielded you got to remember
00:17:38.470 00:17:38.480 we have an oscilloscope that's down at
00:17:40.510 00:17:40.520 about 5 millivolts per division and
00:17:42.310 00:17:42.320 maybe even 1 millivolt per division so
00:17:45.040 00:17:45.050 if we have a plastic box a lot of noise
00:17:47.320 00:17:47.330 is going to get into there from anything
00:17:49.210 00:17:49.220 that's basically around it the thing is
00:17:51.190 00:17:51.200 any kind of wire length inside this box
00:17:53.680 00:17:53.690 if it was plastic would act as an
00:17:56.230 00:17:56.240 antenna and we'd be picking up all sorts
00:17:57.730 00:17:57.740 of just noise and random garbage so
00:18:00.820 00:18:00.830 we want to do is we want to have
00:18:02.110 00:18:02.120 everything enclosed in a solid a cast
00:18:04.899 00:18:04.909 box here another thing that we have to
00:18:07.899 00:18:07.909 think about is you know a battery so I'm
00:18:10.539 00:18:10.549 going to need to install a battery in
00:18:11.950 00:18:11.960 here now most likely going to end up
00:18:13.210 00:18:13.220 using a 9-volt battery for this so you
00:18:15.730 00:18:15.740 know it's going to take up a small
00:18:16.870 00:18:16.880 portion of this box so I have to locate
00:18:19.659 00:18:19.669 things inside of this project box so
00:18:22.029 00:18:22.039 that you know this whole thing will work
00:18:23.620 00:18:23.630 out you know I need to put a BNC jack on
00:18:26.200 00:18:26.210 here you know all I need to put a switch
00:18:27.820 00:18:27.830 on it somewhere the battery will have to
00:18:30.070 00:18:30.080 be mounted in here they'll have to be a
00:18:31.330 00:18:31.340 small circuit board in here that you
00:18:34.299 00:18:34.309 know all of our parts and pieces are
00:18:35.710 00:18:35.720 going to be on and we also have to think
00:18:38.049 00:18:38.059 if we're going to say I'm going to have
00:18:39.639 00:18:39.649 two alligator clips sticking out of the
00:18:41.620 00:18:41.630 top of this box or something like that
00:18:44.159 00:18:44.169 alright now I'm going to also have to
00:18:46.419 00:18:46.429 have an LED beside each alligator clip
00:18:49.690 00:18:49.700 so that I know when this thing is moving
00:18:51.669 00:18:51.679 around like this one it's reversing the
00:18:53.409 00:18:53.419 polarity of the capacitor so that we can
00:18:55.779 00:18:55.789 note that you know the amplitude
00:18:56.919 00:18:56.929 difference on the screen we're going to
00:18:58.690 00:18:58.700 have to have something that's going to
00:19:00.009 00:19:00.019 mark the side that's the band end so I'm
00:19:03.250 00:19:03.260 going to have to have maybe some rubber
00:19:04.539 00:19:04.549 grommets and then you know maybe some
00:19:06.549 00:19:06.559 LEDs on the top of the box so everything
00:19:09.220 00:19:09.230 has to be taken into account because we
00:19:10.810 00:19:10.820 can't you know push the battery down on
00:19:12.340 00:19:12.350 top of the LEDs and we also need space
00:19:15.129 00:19:15.139 for the for the wires to come out of the
00:19:17.830 00:19:17.840 top of the box so the battery will have
00:19:20.049 00:19:20.059 to sit over to one side and this is all
00:19:21.639 00:19:21.649 stuff that you have to think about
00:19:22.629 00:19:22.639 before you plan this so what you do is
00:19:25.659 00:19:25.669 of course you get your box and you know
00:19:27.129 00:19:27.139 you put the battery inside and you move
00:19:28.899 00:19:28.909 things around and you know you pawned
00:19:31.149 00:19:31.159 over some things for a little while and
00:19:33.100 00:19:33.110 then when you you know come to thinking
00:19:35.529 00:19:35.539 okay you know this layout is going to
00:19:37.330 00:19:37.340 work then of course you can start
00:19:38.860 00:19:38.870 building with that layout so now in
00:19:42.399 00:19:42.409 order for this to make testing easier we
00:19:45.279 00:19:45.289 obviously need some form of a circuit
00:19:46.960 00:19:46.970 that's going to take this you know
00:19:49.299 00:19:49.309 capacitor and it's going to reverse it
00:19:51.430 00:19:51.440 and of course we don't want any imposed
00:19:53.470 00:19:53.480 noise from the circuit that it's around
00:19:55.830 00:19:55.840 so in order to make a circuit that's
00:19:58.899 00:19:58.909 going to reverse this we're going to
00:20:00.610 00:20:00.620 need something that's going to look like
00:20:03.039 00:20:03.049 this
00:20:14.779 00:20:14.789 so we can look at this as right here if
00:20:18.049 00:20:18.059 we were to have the capacitor under test
00:20:20.299 00:20:20.309 right here this is the capacitor under
00:20:23.930 00:20:23.940 test okay and say this here is the the
00:20:27.829 00:20:27.839 scope common and this is the scope you
00:20:31.909 00:20:31.919 know that the center conductor will just
00:20:33.649 00:20:33.659 put plus here for just for ease of
00:20:36.439 00:20:36.449 drawing okay so this is the center
00:20:38.629 00:20:38.639 conductor of the oscilloscope probe and
00:20:40.819 00:20:40.829 this here is the scope probe common so
00:20:44.599 00:20:44.609 if we want to have this in the circuit
00:20:46.969 00:20:46.979 say this is the negative side of the
00:20:48.379 00:20:48.389 capacitor here we're going to need to
00:20:50.659 00:20:50.669 close this switch and we're going to
00:20:53.269 00:20:53.279 need to close this switch in order for
00:20:55.249 00:20:55.259 the positive probe of our oscilloscope
00:20:57.979 00:20:57.989 or the center conductor of the cable to
00:21:00.019 00:21:00.029 be attached to this side of the
00:21:01.430 00:21:01.440 capacitor which then would make this
00:21:03.589 00:21:03.599 this side here and then of course this
00:21:06.049 00:21:06.059 would run to ground so you can see we
00:21:07.699 00:21:07.709 have a circuit here now so then in order
00:21:10.489 00:21:10.499 to reverse this capacitor in order to
00:21:12.559 00:21:12.569 flip it these two switches would have to
00:21:14.389 00:21:14.399 open and then this switch and this
00:21:17.329 00:21:17.339 switch would have to close and then of
00:21:19.369 00:21:19.379 course that would make this side running
00:21:22.009 00:21:22.019 up to the to the center conductor here
00:21:23.869 00:21:23.879 and then this side here would end up
00:21:25.819 00:21:25.829 becoming the common side because this
00:21:28.430 00:21:28.440 switch is connected to ground and we're
00:21:30.229 00:21:30.239 going to also need some form of say an
00:21:33.169 00:21:33.179 LED or something at this point to denote
00:21:37.819 00:21:37.829 when this side here is the the common
00:21:41.389 00:21:41.399 side or whether this side here is going
00:21:43.519 00:21:43.529 to be the common side so we're going to
00:21:45.079 00:21:45.089 also need two LEDs to do that so now we
00:21:48.680 00:21:48.690 can do this with relays and of course
00:21:50.719 00:21:50.729 we're going to have a little bit of
00:21:51.559 00:21:51.569 current consumption if we do that we're
00:21:53.180 00:21:53.190 going to here click click click click
00:21:54.349 00:21:54.359 inside this box or we can do this within
00:21:57.409 00:21:57.419 IC and I'll probably end up using an IC
00:22:00.439 00:22:00.449 because there's a you know limited
00:22:02.499 00:22:02.509 current draw with n IC we you know
00:22:05.029 00:22:05.039 there's a bunch of ICS that that
00:22:06.469 00:22:06.479 basically work as a single pole single
00:22:09.229 00:22:09.239 throw switches and you know I'll find
00:22:12.379 00:22:12.389 something that's rather common to use
00:22:14.359 00:22:14.369 and we'll make this particular circuit
00:22:17.389 00:22:17.399 using a bunch of ICS now if we use an IC
00:22:19.519 00:22:19.529 and it's got a bunch of fats inside it
00:22:21.529 00:22:21.539 we're going to also want to have
00:22:23.180 00:22:23.190 something on you know this particular
00:22:25.129 00:22:25.139 point here which basically is you know
00:22:27.829 00:22:27.839 to do
00:22:28.610 00:22:28.620 like this one diode like this and one
00:22:31.400 00:22:31.410 diode like this and that's going to also
00:22:33.350 00:22:33.360 limit this basically to about point six
00:22:36.799 00:22:36.809 or 0.7 of a volt on each side so just
00:22:38.870 00:22:38.880 say there's a bit of a charge on that
00:22:40.400 00:22:40.410 capacitor so you forgot to discharge it
00:22:42.590 00:22:42.600 a little bit or if there's you know you
00:22:44.570 00:22:44.580 have static you're not going to zap this
00:22:46.940 00:22:46.950 I see if we use an IC so this is
00:22:49.190 00:22:49.200 basically just going to protect it and
00:22:50.630 00:22:50.640 limit the voltage that goes into the
00:22:53.090 00:22:53.100 circuit now of course you would always
00:22:54.740 00:22:54.750 make sure every single capacitor is
00:22:56.690 00:22:56.700 discharged before you stick it into
00:22:58.549 00:22:58.559 circuit and all this is going to do is
00:23:00.740 00:23:00.750 protect the eye see that these switches
00:23:02.720 00:23:02.730 are in and of course we would want the
00:23:04.400 00:23:04.410 same thing on this particular side here
00:23:07.280 00:23:07.290 and it would be exactly like this so
00:23:11.030 00:23:11.040 basically all that's doing is this is
00:23:12.440 00:23:12.450 limiting this input circuit were cap
00:23:15.020 00:23:15.030 acid or under test is to about point
00:23:16.790 00:23:16.800 seven of a volt now keep in mind that
00:23:18.710 00:23:18.720 we're testing most of this down at
00:23:20.480 00:23:20.490 00:23:20.990 00:23:21.000 oh no 10 you know maybe you know with
00:23:23.870 00:23:23.880 our amplitude maybe we're exceeding 50
00:23:26.150 00:23:26.160 60 70 millivolts with the humming are
00:23:28.220 00:23:28.230 and that we're imposing into this
00:23:30.410 00:23:30.420 capacitor who knows but this is going to
00:23:32.930 00:23:32.940 be up around six or seven hundred
00:23:35.200 00:23:35.210 millivolts just about a volt so you know
00:23:39.020 00:23:39.030 this is a well beyond our our our test
00:23:42.200 00:23:42.210 so this is just protecting this here so
00:23:45.710 00:23:45.720 now we're going to also need to do is
00:23:47.030 00:23:47.040 we're going to need to implement some
00:23:48.620 00:23:48.630 sort of a circuit that's going to close
00:23:50.030 00:23:50.040 these two and close these two and then
00:23:52.400 00:23:52.410 it's going to have to do this right in
00:23:53.960 00:23:53.970 order to flip this capacitor back and
00:23:56.390 00:23:56.400 forth and back and forth so we're going
00:23:59.030 00:23:59.040 to need some sort of a flip-flop
00:24:00.620 00:24:00.630 probably a D type flip-flop or something
00:24:03.169 00:24:03.179 like that and then if this is an in and
00:24:05.810 00:24:05.820 I see these are going to be controlled
00:24:07.669 00:24:07.679 so this side here right and this side
00:24:11.510 00:24:11.520 here would go to one leg of the
00:24:13.669 00:24:13.679 flip-flop and then this side here and of
00:24:16.400 00:24:16.410 course this side here would go to
00:24:17.900 00:24:17.910 another part of the foot flip-flop now
00:24:20.299 00:24:20.309 keep in mind that this is just only a
00:24:22.010 00:24:22.020 rough sketch and I'm just trying to get
00:24:24.140 00:24:24.150 the idea across when it comes to
00:24:26.360 00:24:26.370 actually designing this we'll go over to
00:24:28.160 00:24:28.170 the whiteboard and take a look at it
00:24:30.200 00:24:30.210 there so now that we have a flip-flop
00:24:32.390 00:24:32.400 that's basically just going back and
00:24:33.770 00:24:33.780 forth like this you know once this one
00:24:36.080 00:24:36.090 this side is positive say you know we're
00:24:38.900 00:24:38.910 going to probably not use a just a 74 Hz
00:24:42.350 00:24:42.360 we will probably use a CD 74 HCI C's for
00:24:47.480 00:24:47.490 this because we are dealing with a
00:24:48.860 00:24:48.870 9-volt battery just 74 Hz logic is
00:24:51.890 00:24:51.900 usually only good to between both 5 & 7
00:24:54.080 00:24:54.090 volts maximum so we're going to be using
00:24:56.330 00:24:56.340 a 9-volt battery so we're going to be
00:24:57.770 00:24:57.780 wanting to use parts that start with CD
00:25:00.680 00:25:00.690 and of course we'll take a look at the
00:25:02.090 00:25:02.100 data sheet just to make sure that you
00:25:04.340 00:25:04.350 know it will be fine around the 9-volt
00:25:06.590 00:25:06.600 area so now that we have this this this
00:25:10.220 00:25:10.230 type flip-flop here now we need also a
00:25:12.020 00:25:12.030 timer that's going to set out a pulse
00:25:14.330 00:25:14.340 into this that's going to tell this to
00:25:16.610 00:25:16.620 go back and forth like this so of course
00:25:19.760 00:25:19.770 when this side is high this side is low
00:25:21.740 00:25:21.750 right and then when this side is high
00:25:23.390 00:25:23.400 this side is low so basically what this
00:25:25.370 00:25:25.380 is going to do is it's just going to
00:25:26.510 00:25:26.520 close these two switches and then close
00:25:28.580 00:25:28.590 these two switches and then close these
00:25:30.320 00:25:30.330 two so you know when these two are
00:25:32.090 00:25:32.100 closed these are open obviously and it's
00:25:34.070 00:25:34.080 just going to go back and forth like
00:25:35.450 00:25:35.460 this and we also want to set the timing
00:25:38.210 00:25:38.220 rate of this timer so that when we have
00:25:41.570 00:25:41.580 this thing on the bench and we're
00:25:43.250 00:25:43.260 looking at say our oscilloscope here we
00:25:45.650 00:25:45.660 want it to go slow enough so that when
00:25:47.360 00:25:47.370 we can see the amplitude change on our
00:25:49.400 00:25:49.410 oscilloscope the amplitude goes down and
00:25:52.160 00:25:52.170 then the amplitude goes up we want to
00:25:53.720 00:25:53.730 have a chance when it goes down again to
00:25:56.060 00:25:56.070 look at the box and note which led on
00:25:58.640 00:25:58.650 which side of the box is going to be led
00:26:01.010 00:26:01.020 up so when we know that you know the
00:26:03.350 00:26:03.360 amplitude is low and this led is lit up
00:26:05.450 00:26:05.460 we'll know that this side here would be
00:26:07.490 00:26:07.500 the band end of the capacitor so that's
00:26:10.220 00:26:10.230 what we want to try and do so these are
00:26:11.720 00:26:11.730 the parameters that we're basically
00:26:12.950 00:26:12.960 dealing with we have a 9-volt battery so
00:26:15.440 00:26:15.450 we know that we're going to need like
00:26:16.610 00:26:16.620 you know is s CD 74 HC parts or just CD
00:26:20.060 00:26:20.070 parts the 555 timer is good for nine
00:26:23.210 00:26:23.220 volts so we don't really have to worry
00:26:24.440 00:26:24.450 about that we'll use a five five five
00:26:26.000 00:26:26.010 over here probably a D flip-flop or
00:26:28.310 00:26:28.320 something like that and I'll have to
00:26:31.130 00:26:31.140 figure out some really common part for
00:26:33.290 00:26:33.300 this so that way you know it's easy to
00:26:35.840 00:26:35.850 put together now if you have a bigger
00:26:37.730 00:26:37.740 box you don't need to use a small box
00:26:39.440 00:26:39.450 like I'm doing you can build this onto
00:26:41.210 00:26:41.220 that dumb you know that proto board
00:26:43.010 00:26:43.020 stuff and you can use through-hole icees
00:26:45.140 00:26:45.150 I'll probably end up building this for
00:26:47.450 00:26:47.460 myself with surface mount stuff just so
00:26:49.310 00:26:49.320 that I can fit it right inside this box
00:26:51.620 00:26:51.630 and then you know this box will have a B
00:26:53.300 00:26:53.310 and C come off of it and a power switch
00:26:55.910 00:26:55.920 and it'll probably have two little
00:26:56.780 00:26:56.790 alligator clips now the the cables that
00:26:59.690 00:26:59.700 are going to come out of this box I want
00:27:01.100 00:27:01.110 to be shielded right up to the alligator
00:27:03.380 00:27:03.390 clips because you know if we have just
00:27:05.360 00:27:05.370 two long wires sticking out of here
00:27:06.770 00:27:06.780 those are really to acting as two
00:27:08.540 00:27:08.550 antennas so the more shielding we can
00:27:10.760 00:27:10.770 get right up to the alligator clips the
00:27:12.680 00:27:12.690 better so I'll have two small shielded
00:27:14.930 00:27:14.940 pieces of coax coming up here and of
00:27:16.790 00:27:16.800 course we want you know a little bit of
00:27:18.200 00:27:18.210 lead length so we can move them around
00:27:19.550 00:27:19.560 if we have you know large axial
00:27:21.620 00:27:21.630 capacitor we can clip them onto the ends
00:27:23.690 00:27:23.700 or if we have one of the newer style
00:27:26.330 00:27:26.340 ones we have this one here we have one
00:27:28.640 00:27:28.650 of the newer style ones like this you
00:27:30.140 00:27:30.150 know we can just you know put the two
00:27:31.580 00:27:31.590 leads together and clip them in like
00:27:33.080 00:27:33.090 this so the whole idea is to make this
00:27:35.420 00:27:35.430 thing functional especially if you're
00:27:37.100 00:27:37.110 going through all sorts of different
00:27:38.210 00:27:38.220 types of capacitors you know we want
00:27:40.160 00:27:40.170 this thing to be about just as versatile
00:27:42.020 00:27:42.030 as we can make it so now that we have
00:27:44.660 00:27:44.670 the plan here I'll figure out an actual
00:27:47.210 00:27:47.220 circuit and I'll draw it up and we'll
00:27:48.680 00:27:48.690 head on over to the white board and I'll
00:27:50.510 00:27:50.520 explain it there this is the circuit
00:27:53.780 00:27:53.790 I've designed for our little capacitor
00:27:55.340 00:27:55.350 testing so I ended up using a CD 74 HC
00:27:59.240 00:27:59.250 four zero six six to flip the capacitor
00:28:02.330 00:28:02.340 around in circuit now this is an IC and
00:28:04.430 00:28:04.440 it's a CD 74 HC four zero six six it's
00:28:08.390 00:28:08.400 not just a 74 HC four oh six six and the
00:28:10.730 00:28:10.740 reason that I use this one is that it
00:28:12.980 00:28:12.990 will go up to ten volts remember that we
00:28:15.080 00:28:15.090 need to keep the supply voltage of our
00:28:16.850 00:28:16.860 ICS well within a safe zone I'm using a
00:28:19.670 00:28:19.680 nine volt battery over here to power
00:28:21.530 00:28:21.540 this and again this is all just due to
00:28:23.300 00:28:23.310 size constraints I have that little
00:28:25.580 00:28:25.590 aluminum box or that little cast box
00:28:27.560 00:28:27.570 that I showed you that I'm going to end
00:28:28.970 00:28:28.980 up fitting this all in if it's around
00:28:31.100 00:28:31.110 here somewhere I still haven't found it
00:28:32.450 00:28:32.460 but I'll fit all that into that box
00:28:35.500 00:28:35.510 again you know you can build this into
00:28:37.670 00:28:37.680 any kind of size box if you have a
00:28:38.930 00:28:38.940 larger aluminum box you can you know of
00:28:41.420 00:28:41.430 course use a different kind of battery
00:28:43.730 00:28:43.740 style power source for this at you know
00:28:46.010 00:28:46.020 a bunch of double-a batteries or
00:28:47.090 00:28:47.100 whatever fits in that box just keep in
00:28:48.890 00:28:48.900 mind that the box has to be either solid
00:28:50.810 00:28:50.820 metal or solid aluminum or a cast box
00:28:53.120 00:28:53.130 some sort of conductive box because
00:28:55.400 00:28:55.410 again our Cilla scope is running down
00:28:57.350 00:28:57.360 you know between 1 and 5 millivolts it's
00:28:59.240 00:28:59.250 going to pick up any kind of noise no
00:29:01.280 00:29:01.290 power supplies running into this thing
00:29:02.750 00:29:02.760 at all it should be battery-powered so
00:29:06.080 00:29:06.090 we'll get back to the circuit I've drawn
00:29:07.430 00:29:07.440 this I see the same way that you would
00:29:09.320 00:29:09.330 kinda
00:29:09.650 00:29:09.660 look at Relays just yet make it a little
00:29:11.510 00:29:11.520 bit easier to understand so how this IC
00:29:13.970 00:29:13.980 works is really quite simple it really
00:29:15.740 00:29:15.750 is just four switches inside of one IC
00:29:18.440 00:29:18.450 so pin 13 pin 5 pin 12 and pin 6 are the
00:29:22.040 00:29:22.050 control pins so say pin 13 goes high
00:29:24.580 00:29:24.590 that'll connect pin 2 and pin 1 so
00:29:27.140 00:29:27.150 technically it just closes the switch
00:29:28.310 00:29:28.320 inside so pin 13 and pin 6 are tied
00:29:31.430 00:29:31.440 together pin 12 and pin 3 are tied
00:29:33.530 00:29:33.540 together so basically it's just closing
00:29:35.420 00:29:35.430 the switches like this and this is all
00:29:37.400 00:29:37.410 done within an IC there's very low
00:29:39.440 00:29:39.450 current consumption you don't get the
00:29:40.850 00:29:40.860 clicking from a relay and you know it's
00:29:43.550 00:29:43.560 a it's a real consistent test because
00:29:45.380 00:29:45.390 we're using FETs inside this in order to
00:29:47.300 00:29:47.310 switch this in circuit now there will be
00:29:49.700 00:29:49.710 a little bit of resistance in the switch
00:29:52.010 00:29:52.020 and I'll explain that a little bit it's
00:29:53.960 00:29:53.970 between 15 and 20 ohms but that's
00:29:56.150 00:29:56.160 absolutely fine for testing these
00:29:57.800 00:29:57.810 capacitors there'll be no issues with
00:29:59.540 00:29:59.550 this whatsoever
00:30:00.350 00:30:00.360 so this was a really good solution the
00:30:02.330 00:30:02.340 cd70 for AC 4 0 6 6 is a really common
00:30:05.660 00:30:05.670 part it's an off-the-shelf part you
00:30:07.400 00:30:07.410 should be able to find out with no
00:30:08.420 00:30:08.430 problems again you can build this
00:30:09.950 00:30:09.960 through-hole you don't need to build a
00:30:11.450 00:30:11.460 surface mount the only reason I'm
00:30:12.620 00:30:12.630 building this surface no it's because in
00:30:14.180 00:30:14.190 my little box it's is hiding here
00:30:16.550 00:30:16.560 somewhere and I'll put all the stuff
00:30:18.350 00:30:18.360 inside that little box so ah these are
00:30:21.530 00:30:21.540 b'av 99s these are just their two diodes
00:30:24.950 00:30:24.960 in 1 SOT 23 package you don't need to
00:30:28.220 00:30:28.230 use the Vav 99 you can use a 1 and 4 1 5
00:30:31.220 00:30:31.230 2 or a 1 and 9 1 4 or if you think
00:30:34.550 00:30:34.560 you're going to be crazy and leave a
00:30:35.750 00:30:35.760 capacitor charge and stuff it into the
00:30:37.640 00:30:37.650 circuit you can use a 1 in 4 double O 7
00:30:41.000 00:30:41.010 s or whatever you want to use remember
00:30:42.500 00:30:42.510 this is just working at a really low
00:30:44.690 00:30:44.700 frequency is you know you're coupling
00:30:46.670 00:30:46.680 the 60 cycle signaling from your body
00:30:49.100 00:30:49.110 really and you know just you know
00:30:51.140 00:30:51.150 inducing hum into the circuit so that
00:30:52.970 00:30:52.980 you can see which end is the shielded
00:30:54.590 00:30:54.600 end so really not too picky so I use the
00:30:57.410 00:30:57.420 Vav 99s just because they fit on a
00:30:59.060 00:30:59.070 little circuit board quite nicely so and
00:31:01.550 00:31:01.560 all I'll get into this here in a little
00:31:03.950 00:31:03.960 bit I've already got that little circuit
00:31:05.570 00:31:05.580 board already pre drawn and ready to go
00:31:07.940 00:31:07.950 and we'll get into that next I'll show
00:31:09.710 00:31:09.720 you how I've drawn that up so that's one
00:31:11.780 00:31:11.790 of the reasons that I use these they
00:31:12.980 00:31:12.990 just they fit on there really quite
00:31:14.270 00:31:14.280 nicely so now here I've got a CD 401 3
00:31:18.710 00:31:18.720 which is a flip-flop is a D style
00:31:20.420 00:31:20.430 flip-flop and what that what this
00:31:23.389 00:31:23.399 really does is when it receives a pulse
00:31:25.459 00:31:25.469 in pin 11 of this I see what it does is
00:31:28.339 00:31:28.349 it just basically this pin will go high
00:31:30.649 00:31:30.659 this will go low and then it will
00:31:32.269 00:31:32.279 receive another pulse and it turns the
00:31:33.680 00:31:33.690 other way and it just keeps going back
00:31:35.209 00:31:35.219 and forth like this now you can see I've
00:31:37.609 00:31:37.619 got two really high brightness LEDs here
00:31:40.219 00:31:40.229 and the reason that they're high
00:31:41.539 00:31:41.549 brightness is because I'm using a 22 K
00:31:44.419 00:31:44.429 to ground resistor and you can use one
00:31:47.299 00:31:47.309 or two it really doesn't matter the
00:31:49.159 00:31:49.169 reason they're I'm using this is because
00:31:50.719 00:31:50.729 they pull very very low current and they
00:31:53.269 00:31:53.279 are still pretty bright at that point so
00:31:55.339 00:31:55.349 I don't want to use up my battery power
00:31:57.349 00:31:57.359 lighting LEDs you got to remember in the
00:31:59.479 00:31:59.489 circuit one LED will always be on it's
00:32:01.909 00:32:01.919 just going back and forth so when this
00:32:04.820 00:32:04.830 side here goes high this LED will glow
00:32:07.489 00:32:07.499 now this LED here should be positioned
00:32:11.149 00:32:11.159 by the negative part of the switch so
00:32:14.299 00:32:14.309 pin eight and pin nine it were pin pin
00:32:17.690 00:32:17.700 four and pin eight run out to your
00:32:19.099 00:32:19.109 alligator clip that's where this LED
00:32:21.619 00:32:21.629 should be located alright so where this
00:32:25.039 00:32:25.049 LED should be located should be close to
00:32:27.589 00:32:27.599 pin 1 and pin 11 so what's going to
00:32:30.139 00:32:30.149 happen is is when this side goes high it
00:32:32.810 00:32:32.820 closes this switch and that what that's
00:32:35.389 00:32:35.399 doing is that's bringing this side of
00:32:37.009 00:32:37.019 the capacitor to ground and we remember
00:32:40.310 00:32:40.320 that we're looking for the negative side
00:32:41.749 00:32:41.759 of the capacitor or the shielded side of
00:32:43.519 00:32:43.529 the capacitor and you want this LED
00:32:45.889 00:32:45.899 close to this side you want the red LED
00:32:48.200 00:32:48.210 close to this side so when this side
00:32:50.419 00:32:50.429 goes high this one here is pulling this
00:32:52.579 00:32:52.589 side of the capacitor to ground again
00:32:54.739 00:32:54.749 we're looking for the shielded side of
00:32:57.079 00:32:57.089 the capacitor if you have the LEDs
00:32:59.029 00:32:59.039 reversed you'll end up marking the wrong
00:33:01.070 00:33:01.080 side of your capacitor and I'll show you
00:33:02.810 00:33:02.820 how to test for that in the end to make
00:33:04.489 00:33:04.499 sure that you have the LED on the right
00:33:06.259 00:33:06.269 end just in case that's a little bit
00:33:08.060 00:33:08.070 confusing again the we have a pulse
00:33:11.570 00:33:11.580 going into pin 11 here so again this is
00:33:13.310 00:33:13.320 just going like this and you can see the
00:33:14.930 00:33:14.940 action with the LEDs the LED you'll see
00:33:16.909 00:33:16.919 the LEDs move back and forth this is a
00:33:19.129 00:33:19.139 five five five timer and what this
00:33:21.409 00:33:21.419 little 555 timer is doing is just
00:33:22.969 00:33:22.979 creating the pulses in order to tell
00:33:24.739 00:33:24.749 this flip-flop to do its flip-flopping
00:33:26.930 00:33:26.940 so it's just going to keep it doing this
00:33:28.849 00:33:28.859 now I chose a 180 K resistor in a 1k
00:33:32.419 00:33:32.429 resistor because I find that to be a
00:33:34.039 00:33:34.049 very nice balance you don't want this to
00:33:36.379 00:33:36.389 go too
00:33:37.130 00:33:37.140 because you're not going to be able to
00:33:38.150 00:33:38.160 look at the screen and then all you know
00:33:39.470 00:33:39.480 really quickly look down to the box and
00:33:40.820 00:33:40.830 then see which LEDs letting mark the
00:33:42.290 00:33:42.300 line on it right you want enough time so
00:33:44.270 00:33:44.280 that you know when you see the the
00:33:45.860 00:33:45.870 amplitude goes small you can look at the
00:33:47.900 00:33:47.910 box see which LEDs lit and draw a line
00:33:49.970 00:33:49.980 on and then by that time it's already
00:33:51.350 00:33:51.360 back over to the other side again and
00:33:53.240 00:33:53.250 I'll explain all this in the end and
00:33:55.580 00:33:55.590 you'll see how this actually functions
00:33:57.140 00:33:57.150 so you can speed this up if you want if
00:33:59.690 00:33:59.700 you find that this is a little bit too
00:34:01.070 00:34:01.080 slow and you know you want to be
00:34:02.540 00:34:02.550 Superman as you're you know grading all
00:34:04.760 00:34:04.770 your capacitors in your uterus hammering
00:34:06.710 00:34:06.720 them through really quick you can change
00:34:08.419 00:34:08.429 this 180 K resistor down to 150 K and
00:34:11.360 00:34:11.370 it's going to go quicker 120 K and
00:34:13.550 00:34:13.560 you're really working alright if you
00:34:15.889 00:34:15.899 find that 180 K is too fast up into 220
00:34:18.860 00:34:18.870 and you'll have plenty of time to sit
00:34:20.750 00:34:20.760 there and have a sleep between the LEDs
00:34:22.850 00:34:22.860 as they're switching back and forth okay
00:34:25.040 00:34:25.050 so this hundred an eighty K resistor you
00:34:27.350 00:34:27.360 can put a VR in there again I'm keeping
00:34:29.570 00:34:29.580 it simple I'm I'm dealing with size
00:34:31.490 00:34:31.500 constraint because of that little box
00:34:33.169 00:34:33.179 that I've got so I just want this thing
00:34:35.870 00:34:35.880 basically turn on a switch and the thing
00:34:37.580 00:34:37.590 just starts doing its action and I can
00:34:39.139 00:34:39.149 great cap so it's just a happy medium so
00:34:41.630 00:34:41.640 180 K and 1 K work very well I'm using a
00:34:44.540 00:34:44.550 22 mic tantalum capacitor down here and
00:34:47.690 00:34:47.700 the reason I'm using a 22 mic tantalum
00:34:49.730 00:34:49.740 capacitor is because I have a lot of
00:34:51.169 00:34:51.179 them so that's really the only reason
00:34:53.470 00:34:53.480 there's a point 0 1 cap coming off of 5
00:34:56.180 00:34:56.190 just to keep noise out of the 5 5 5
00:34:58.870 00:34:58.880 you'll see here that these are all the
00:35:00.980 00:35:00.990 supply lines for all the ICS we have pin
00:35:03.830 00:35:03.840 14 and pin 14 pin 7 and pin 7 for both
00:35:06.620 00:35:06.630 of these ICS
00:35:07.610 00:35:07.620 and for 8 and 1 for the 5 5 5 so 14 14 4
00:35:12.620 00:35:12.630 and 8 are all positive so 4 & 8 and this
00:35:15.020 00:35:15.030 is pin 14 and there's a pin 14 on this
00:35:16.970 00:35:16.980 that also has to be tied to positive and
00:35:18.710 00:35:18.720 we have pin 7 pin 7 and pin 1 so there's
00:35:21.890 00:35:21.900 a pin 7 on this IC that has to go to
00:35:23.630 00:35:23.640 ground there is a pin 7 on this IC as we
00:35:26.780 00:35:26.790 can see here that goes to ground and
00:35:28.220 00:35:28.230 then we have pin 1 here going to ground
00:35:29.870 00:35:29.880 and that's really just the supply again
00:35:31.610 00:35:31.620 you can put the switch in the positive
00:35:32.840 00:35:32.850 or the negative side absolutely fine
00:35:34.430 00:35:34.440 whatever you think will work just fine
00:35:36.950 00:35:36.960 for you so I've got a 22 mic cap on the
00:35:40.220 00:35:40.230 supply here just to keep noise out of
00:35:42.590 00:35:42.600 the circuit when this thing is switching
00:35:44.650 00:35:44.660 what else can I tell you here I think
00:35:47.600 00:35:47.610 that's pretty much it this will draw
00:35:50.270 00:35:50.280 between
00:35:50.960 00:35:50.970 to eight milliamps somewhere in there
00:35:53.210 00:35:53.220 depending on the ICS and the
00:35:55.190 00:35:55.200 manufacturer and everything that's
00:35:57.710 00:35:57.720 really quite nice if you use release
00:35:59.300 00:35:59.310 you're going to end up with quite a bit
00:36:01.250 00:36:01.260 more current consumption so that was the
00:36:03.530 00:36:03.540 whole idea of of using a 9-volt battery
00:36:06.500 00:36:06.510 and a bunch of ICS we can you know we'll
00:36:08.569 00:36:08.579 get a really long life out of this out
00:36:11.660 00:36:11.670 of this little switch so everything
00:36:13.400 00:36:13.410 should work just fine
00:36:14.390 00:36:14.400 scope common goes to pin 10 and pin 9 so
00:36:17.450 00:36:17.460 basically pin 9 and pin 10 of the 406 6
00:36:20.180 00:36:20.190 we'll just tie to the chassis or to the
00:36:22.069 00:36:22.079 box and then the BNC Center that you
00:36:24.980 00:36:24.990 have coming rate that goes right out
00:36:26.930 00:36:26.940 into your oscilloscope will tie rate to
00:36:29.089 00:36:29.099 pin 2 and pin 3 so and of course that's
00:36:32.690 00:36:32.700 that's you know a continual and then you
00:36:35.630 00:36:35.640 know this isn't moving this is your
00:36:37.220 00:36:37.230 scope pot yours in your scope comm
00:36:38.809 00:36:38.819 there's nothing moving there that's that
00:36:40.040 00:36:40.050 stays there and then of course the
00:36:41.630 00:36:41.640 switching is going to do its switching
00:36:42.950 00:36:42.960 at that point inside the IC and flip
00:36:44.960 00:36:44.970 that capacitor around as this 555 timer
00:36:48.170 00:36:48.180 is telling this flip-flop to go back and
00:36:49.970 00:36:49.980 forth and that's pretty much it so what
00:36:53.839 00:36:53.849 I'll do is I'll take you over to the
00:36:54.859 00:36:54.869 computer now and I'll show you the
00:36:56.809 00:36:56.819 little layout that I've got designed up
00:36:59.510 00:36:59.520 and it's a service mount layout again
00:37:01.040 00:37:01.050 you don't have to do it surface mount
00:37:02.390 00:37:02.400 you can build it through-hole or however
00:37:03.559 00:37:03.569 you want to build this you can build a
00:37:05.120 00:37:05.130 dead bug style whatever works for you
00:37:08.150 00:37:08.160 so let's head on over to the computer
00:37:10.480 00:37:10.490 this is the surface mount version
00:37:12.620 00:37:12.630 circuit board that I've come up with for
00:37:14.210 00:37:14.220 this little capacitor tester so this is
00:37:17.630 00:37:17.640 really quite blown up this is a really
00:37:19.280 00:37:19.290 small circuit board but I've just
00:37:20.960 00:37:20.970 enhanced it so that it's easier to see
00:37:22.640 00:37:22.650 on camera here so this is the top layer
00:37:26.599 00:37:26.609 the green layer is the top and the black
00:37:28.490 00:37:28.500 is the backside of the circuit board so
00:37:30.230 00:37:30.240 this is a double-sided circuit board
00:37:31.819 00:37:31.829 this little I see here is the 555 timer
00:37:34.520 00:37:34.530 this is pin 1 this is the timing cap
00:37:36.710 00:37:36.720 that 22 micro farad tantalum here these
00:37:39.349 00:37:39.359 are Oh 402 parts this is 180 K resistor
00:37:42.589 00:37:42.599 this is the 1k resistor and this is the
00:37:44.480 00:37:44.490 point 0 1 micro farad capacitor off pin
00:37:47.000 00:37:47.010 5 this here is the other 22 micro farad
00:37:49.730 00:37:49.740 tantalum that's across the supply this
00:37:52.400 00:37:52.410 here is the cd40 1 3 which is the the
00:37:56.240 00:37:56.250 flip-flop and this is the 4 0 6 6 over
00:37:59.930 00:37:59.940 here the is CD 74 HC 406 6 this is
00:38:03.349 00:38:03.359 what's going to be doing
00:38:04.310 00:38:04.320 switching here these here are the screws
00:38:07.790 00:38:07.800 where it mounts to the chassis of that
00:38:10.250 00:38:10.260 little aluminum or a cast box that I've
00:38:13.130 00:38:13.140 got these are the resistors that's on
00:38:15.920 00:38:15.930 the back side this resistor is a 22 K
00:38:18.290 00:38:18.300 resistor and this is the LED this LED
00:38:20.570 00:38:20.580 correlates to this side this is the test
00:38:23.510 00:38:23.520 lead that runs out this side this is the
00:38:25.460 00:38:25.470 center conductor and I will solder the
00:38:27.200 00:38:27.210 shield or the braid of that little piece
00:38:28.910 00:38:28.920 of coax to this piece of the circuit
00:38:30.800 00:38:30.810 board here and then of course we want
00:38:32.840 00:38:32.850 the LED close to that rubber grommet
00:38:35.150 00:38:35.160 where the where the test lead runs out
00:38:37.280 00:38:37.290 and it's the same for this side this is
00:38:38.630 00:38:38.640 where the center conductor of our test
00:38:40.400 00:38:40.410 lead runs up to the alligator clip the
00:38:42.410 00:38:42.420 shield of the coax will solder to here
00:38:44.240 00:38:44.250 and this LED correlates with this side
00:38:47.920 00:38:47.930 so these are the high brightness LEDs
00:38:50.660 00:38:50.670 here these are 1206 parts here these are
00:38:53.510 00:38:53.520 22 22 K resistors this is where the
00:38:56.780 00:38:56.790 supply or nine volt supply runs in right
00:38:59.120 00:38:59.130 here and this is where the BNC signal
00:39:02.360 00:39:02.370 runs out this goes to the BNC jack on
00:39:04.610 00:39:04.620 the box and that goes out to our Scylla
00:39:06.110 00:39:06.120 scope from this little point here and
00:39:08.180 00:39:08.190 that's really how this works so this is
00:39:11.120 00:39:11.130 really quite small and I'll show you
00:39:12.620 00:39:12.630 exactly how this is going to go together
00:39:14.540 00:39:14.550 here in the next shot here is the
00:39:18.410 00:39:18.420 completed little capacitor testing box
00:39:20.450 00:39:20.460 here we can see that I've got my
00:39:22.820 00:39:22.830 alligator clips fastened to some
00:39:24.440 00:39:24.450 shielded Koh access to some teflon coax
00:39:26.600 00:39:26.610 here the shielding runs up to about this
00:39:28.520 00:39:28.530 point here and about this point here you
00:39:30.770 00:39:30.780 don't need to use teflon coax you can
00:39:32.300 00:39:32.310 use any kind of coax you want I just
00:39:33.650 00:39:33.660 have a bunch of this stuff around I've
00:39:35.870 00:39:35.880 put some heat shrink on the ends here
00:39:37.490 00:39:37.500 just to stiffen things up where that the
00:39:39.530 00:39:39.540 center conductor runs out to the
00:39:41.030 00:39:41.040 alligator clip because you know we're
00:39:42.320 00:39:42.330 going to be moving this around and
00:39:43.520 00:39:43.530 moving in in and out of circuit quite a
00:39:45.410 00:39:45.420 bit and I want to get some longevity out
00:39:47.090 00:39:47.100 of this without having the connections
00:39:48.620 00:39:48.630 break now of course nothing sticks to
00:39:50.660 00:39:50.670 teflon very well so I've left a little
00:39:53.120 00:39:53.130 bit of braid exposed and this heat
00:39:55.190 00:39:55.200 shrink here it has a little bit of glue
00:39:56.780 00:39:56.790 inside of it so it sticks to the braid
00:39:58.250 00:39:58.260 quite nicely and we see the
00:40:00.920 00:40:00.930 corresponding LED for this wire here and
00:40:03.320 00:40:03.330 the corresponding LED for this wire here
00:40:05.300 00:40:05.310 when this LED is lit this one here is
00:40:08.060 00:40:08.070 tied to ground and when this LED is let
00:40:10.640 00:40:10.650 this side here is tied to ground so we
00:40:12.470 00:40:12.480 know which end to mark our band on these
00:40:14.990 00:40:15.000 are two little rubber grommets here that
00:40:16.490 00:40:16.500 I put in this
00:40:17.630 00:40:17.640 is the BNC Jack here that will run out
00:40:19.519 00:40:19.529 to the oscilloscope and there's a bunch
00:40:21.980 00:40:21.990 of screws here that just hold the
00:40:23.269 00:40:23.279 circuit board in and this is the on and
00:40:24.980 00:40:24.990 off switch on the side so on the bottom
00:40:28.190 00:40:28.200 half you can see here I've got a little
00:40:29.509 00:40:29.519 9-volt battery stuck in there and
00:40:31.250 00:40:31.260 there's a little piece of butyl tape
00:40:32.329 00:40:32.339 that's just holding it in this is the
00:40:34.880 00:40:34.890 circuit board that I built and this is
00:40:37.099 00:40:37.109 the little switch in the negative lead
00:40:38.569 00:40:38.579 I'll just zoom in to this here so we can
00:40:40.940 00:40:40.950 take a little closer look at the surface
00:40:43.220 00:40:43.230 mount stuff so you can see the ICS here
00:40:49.700 00:40:49.710 that's the little 555 timer that's the
00:40:52.069 00:40:52.079 406 six down in there and that's the 401
00:40:54.620 00:40:54.630 3 flip-flop and that's the little
00:40:56.930 00:40:56.940 tantalum capacitor the timing cap and so
00:40:59.750 00:40:59.760 on and so forth just like on the layout
00:41:01.370 00:41:01.380 those are all the little Oh 402 parts
00:41:04.009 00:41:04.019 right down there the hundred and eighty
00:41:05.240 00:41:05.250 K the 1k and the the point zero one mic
00:41:08.569 00:41:08.579 capacitor you can see how I've soldered
00:41:12.259 00:41:12.269 the braid of the coax right to the
00:41:14.180 00:41:14.190 circuit board here and then the center
00:41:15.589 00:41:15.599 conductor runs up to this little spot
00:41:17.150 00:41:17.160 this little SOT 23 package part here is
00:41:20.359 00:41:20.369 that b'av 99 diode that's just
00:41:22.370 00:41:22.380 protection so I don't zap the IC in
00:41:24.289 00:41:24.299 there that's the same on this and I
00:41:26.029 00:41:26.039 soldered them in sideways because if I
00:41:27.559 00:41:27.569 ever need to replace them their be
00:41:28.970 00:41:28.980 pretty easy to get out this way and put
00:41:31.279 00:41:31.289 back in again you can use a 1 in 400
00:41:33.200 00:41:33.210 seven or a nine one four or anything
00:41:35.870 00:41:35.880 like that you know it's again we're you
00:41:38.599 00:41:38.609 know we're dealing with 60 cycle
00:41:40.160 00:41:40.170 frequency here so there's nothing that
00:41:41.509 00:41:41.519 needs to be too incredibly fast see what
00:41:44.630 00:41:44.640 else can I tell you those are the LEDs
00:41:45.920 00:41:45.930 that are soldered in you'll see that
00:41:47.599 00:41:47.609 there's a space between the circuit
00:41:48.920 00:41:48.930 board here in the actual case and that's
00:41:50.690 00:41:50.700 because there's parts on the backside of
00:41:52.099 00:41:52.109 the circuit board and there's also a
00:41:53.569 00:41:53.579 soldering on there so when I put the the
00:41:57.380 00:41:57.390 bottom portion of the box together here
00:41:59.930 00:41:59.940 I had to cut this out on the corner here
00:42:02.630 00:42:02.640 and on this corner because the circuit
00:42:04.279 00:42:04.289 board goes you know very close to the
00:42:05.960 00:42:05.970 corner here and they've got this kind of
00:42:07.819 00:42:07.829 extruded lip that runs all the way
00:42:10.220 00:42:10.230 around the entire box here so there's
00:42:13.279 00:42:13.289 enough space between the backside of the
00:42:14.990 00:42:15.000 circuit board and the case to leave this
00:42:16.759 00:42:16.769 strip in here it just goes between the
00:42:18.980 00:42:18.990 circuit board and the case you can see
00:42:21.529 00:42:21.539 here here's the circuit board that will
00:42:23.059 00:42:23.069 go right in between here and that's
00:42:26.029 00:42:26.039 pretty much the box so when we turn the
00:42:28.190 00:42:28.200 thing on this is about the speed that it
00:42:29.809 00:42:29.819 runs out with the
00:42:31.609 00:42:31.619 with the 180k resistor here you can see
00:42:36.120 00:42:36.130 how fast that moves back and forth so
00:42:39.540 00:42:39.550 that gives us enough time to mark our
00:42:40.980 00:42:40.990 capacitor and you know of course look at
00:42:43.650 00:42:43.660 the screen in the you know load a new
00:42:45.240 00:42:45.250 capacitor I think that's about a nice
00:42:47.070 00:42:47.080 comfortable speed for grading these
00:42:48.810 00:42:48.820 capacitors so next let's hook this thing
00:42:51.450 00:42:51.460 up to an oscilloscope and see how it
00:42:53.580 00:42:53.590 works we're ready to check the polarity
00:42:57.540 00:42:57.550 of some capacitors in our test jig so
00:43:00.780 00:43:00.790 I've got the oscilloscope set to 5
00:43:02.400 00:43:02.410 millivolts per division I've got the
00:43:04.650 00:43:04.660 alligator clip shorted here and I'll
00:43:06.330 00:43:06.340 plug this in and I'll show you that it's
00:43:07.560 00:43:07.570 a relatively quiet circuit and see how
00:43:10.770 00:43:10.780 quiet that is right now now you got to
00:43:13.830 00:43:13.840 keep in mind that through this I see
00:43:15.510 00:43:15.520 when this side is grounded it's about 17
00:43:18.270 00:43:18.280 ohms to ground and then when this side
00:43:19.980 00:43:19.990 is on at 17 ohms to ground so we have
00:43:22.410 00:43:22.420 217 or around that own paths 1 from
00:43:25.440 00:43:25.450 positive and 1 to ground and that's just
00:43:27.990 00:43:28.000 the basically the resistance imposed by
00:43:31.050 00:43:31.060 the IC itself so even though we still
00:43:34.410 00:43:34.420 have this you know we're going to still
00:43:36.120 00:43:36.130 pick up noise from the oscilloscope if
00:43:37.920 00:43:37.930 we bring it close to it in everything
00:43:39.960 00:43:39.970 but you know for this actual test this
00:43:42.540 00:43:42.550 is absolutely fine and for this little
00:43:44.310 00:43:44.320 test jiggets is fine so when we open
00:43:46.710 00:43:46.720 these alligator clips you're going to
00:43:47.910 00:43:47.920 see lots of noise on the screen and
00:43:49.800 00:43:49.810 that's absolutely normal because these
00:43:51.480 00:43:51.490 are acting as antennas and this is
00:43:54.120 00:43:54.130 actually just picking up noise from the
00:43:55.680 00:43:55.690 scope itself even you can see the amount
00:43:57.450 00:43:57.460 of noise that comes in from the CRT so
00:44:00.720 00:44:00.730 when we put the capacitor in here under
00:44:02.940 00:44:02.950 test it actually acts as a filter across
00:44:05.190 00:44:05.200 the circuit itself so there is no
00:44:06.750 00:44:06.760 problem with the amount of noise that we
00:44:08.520 00:44:08.530 see so what we'll do now is we'll put a
00:44:11.940 00:44:11.950 capacitor in here let's take this orange
00:44:13.680 00:44:13.690 dip capacitor and test it out and Mark
00:44:16.140 00:44:16.150 the band end so here we have me being
00:44:20.609 00:44:20.619 the 60 cycle antenna again and you can
00:44:24.930 00:44:24.940 see the difference in amplitude here as
00:44:27.080 00:44:27.090 its switching so we see this LED is on
00:44:31.140 00:44:31.150 and the amplitude is lower so this is
00:44:33.480 00:44:33.490 the band end you see so now that we see
00:44:37.620 00:44:37.630 this LED on we would mark this end as
00:44:39.660 00:44:39.670 the band remember we're always looking
00:44:41.130 00:44:41.140 for the lowest amplitude
00:44:47.580 00:44:47.590 so I'll take my Philip marker and I'll
00:44:50.710 00:44:50.720 put a little line on this end and I'll
00:44:53.740 00:44:53.750 know that that now would be the lower
00:44:55.960 00:44:55.970 impedance portion of the circuit this
00:44:57.609 00:44:57.619 would go to the chassis or this side
00:44:59.650 00:44:59.660 would go to the plate side if we have
00:45:01.570 00:45:01.580 this in an amplifier again we can see
00:45:04.839 00:45:04.849 that this side has a band on it but we
00:45:06.460 00:45:06.470 can see that it doesn't really mean
00:45:07.810 00:45:07.820 anything you know according to the
00:45:10.270 00:45:10.280 outside shielding or anything this might
00:45:12.160 00:45:12.170 be some sort of coating that they've put
00:45:13.660 00:45:13.670 on or I don't know what they're doing
00:45:15.250 00:45:15.260 and why they've put this on this one end
00:45:17.020 00:45:17.030 but this side here you know clearly
00:45:20.500 00:45:20.510 denotes the outside foil or the outside
00:45:22.960 00:45:22.970 metallized polypropylene or metallized
00:45:25.359 00:45:25.369 PVC layer okay so there's one so we've
00:45:29.680 00:45:29.690 marked this one and you can see the
00:45:31.810 00:45:31.820 speed is comfortable so that you know
00:45:33.430 00:45:33.440 what's you know you're not losing
00:45:35.020 00:45:35.030 control of what you're doing so put this
00:45:37.330 00:45:37.340 one in all right and I'll put my fingers
00:45:41.050 00:45:41.060 on here all right so we know that this
00:45:47.020 00:45:47.030 end is the band end also okay so I'll
00:45:53.560 00:45:53.570 mark this as the band end now if you
00:45:57.130 00:45:57.140 don't want to leave your felt marker on
00:45:58.660 00:45:58.670 there you know you can use an ink that
00:46:00.760 00:46:00.770 will easily come off I find that you
00:46:03.520 00:46:03.530 know a little bit alcohol will just
00:46:04.690 00:46:04.700 remove these lines even if it is one of
00:46:06.400 00:46:06.410 these sharpies so you know a lot of
00:46:09.160 00:46:09.170 people don't want that line on the
00:46:10.390 00:46:10.400 capacitor when it's in circuit I've kind
00:46:13.510 00:46:13.520 of learned to live with it I kind of
00:46:15.280 00:46:15.290 like to have the the capacitors clean
00:46:16.930 00:46:16.940 myself but that's fine for underneath
00:46:19.390 00:46:19.400 the chassis I'm now just beginning to
00:46:21.160 00:46:21.170 leave the lines on like you will end up
00:46:22.630 00:46:22.640 seeing in most of my videos so this one
00:46:25.300 00:46:25.310 here this side here the this opposite
00:46:27.730 00:46:27.740 side here this one on this side is the
00:46:29.770 00:46:29.780 band end where I've drawn that little
00:46:31.240 00:46:31.250 black line so let's test another one
00:46:45.650 00:46:45.660 so we can see that the opposite end on
00:46:48.109 00:46:48.119 this capacitor is the band end so this
00:46:51.559 00:46:51.569 end is the band end on this capacitor so
00:46:54.049 00:46:54.059 you can see there really is no rhyme or
00:46:55.400 00:46:55.410 reason for these capacitors you know
00:46:58.039 00:46:58.049 they're just kind of going down the line
00:46:59.480 00:46:59.490 any old way they're the same capacitor
00:47:01.819 00:47:01.829 and they're just printing the the the
00:47:04.220 00:47:04.230 labeling on any side there so it really
00:47:06.499 00:47:06.509 is important to mark that off let's test
00:47:10.579 00:47:10.589 out this one here and check out its band
00:47:13.400 00:47:13.410 and okay is that in the shot there it is
00:47:18.049 00:47:18.059 okay I'll put my fingers on here okay so
00:47:26.749 00:47:26.759 this end is the band end right here
00:47:28.720 00:47:28.730 so now we would mark this end as the
00:47:32.269 00:47:32.279 band end and that's just how simple it
00:47:34.670 00:47:34.680 is to grade and check your capacitor so
00:47:37.190 00:47:37.200 you know that you're putting them in
00:47:38.480 00:47:38.490 circuit the correct way and that's how
00:47:41.390 00:47:41.400 this little fixture works so what we're
00:47:44.450 00:47:44.460 going to end up doing next is I'll show
00:47:45.769 00:47:45.779 you how to measure which end is actually
00:47:48.950 00:47:48.960 supposed to be the the negative end so
00:47:52.130 00:47:52.140 that you have your LEDs corresponding to
00:47:54.079 00:47:54.089 the correctly just in case you did find
00:47:55.789 00:47:55.799 that a little bit confusing
00:47:57.819 00:47:57.829 alright this is how we tell how we've
00:48:00.769 00:48:00.779 got the right LED on the right lead so
00:48:04.220 00:48:04.230 this is the lead here that we're going
00:48:05.569 00:48:05.579 to test and we want to know if this LED
00:48:08.359 00:48:08.369 is corresponding to this connecting to
00:48:10.789 00:48:10.799 ground so we've got our our meter on
00:48:12.799 00:48:12.809 ohms and we have our lead going into the
00:48:15.920 00:48:15.930 alligator clip here and you can see that
00:48:18.529 00:48:18.539 at 17 ohms when this LED comes on see
00:48:22.970 00:48:22.980 that so we know that this end is
00:48:24.470 00:48:24.480 connecting to ground and we have our
00:48:26.059 00:48:26.069 polarity right so what I'll do now is
00:48:29.720 00:48:29.730 I'll move this over to this side and
00:48:31.640 00:48:31.650 you'll see roughly the same measurement
00:48:33.289 00:48:33.299 on this side isn't LED there and lamp
00:48:45.279 00:48:45.289 all right let's me trying to get a good
00:48:48.019 00:48:48.029 ground on the box here there we go so
00:48:53.120 00:48:53.130 that's how you tell so if you wire your
00:48:55.759 00:48:55.769 LEDs up and you have them backwards if
00:48:57.440 00:48:57.450 you leave some lead length you can just
00:48:59.210 00:48:59.220 swap them around if you don't build a
00:49:01.039 00:49:01.049 circuit board or something like that and
00:49:02.870 00:49:02.880 that's how you tell that you've got the
00:49:04.880 00:49:04.890 LED connected to the right side well
00:49:11.630 00:49:11.640 we've come to the end of another video I
00:49:13.640 00:49:13.650 hope you find this little circuit useful
00:49:16.190 00:49:16.200 and I hope you enjoyed the video if you
00:49:18.049 00:49:18.059 did give it a big thumbs up and hang
00:49:19.609 00:49:19.619 around I'll try to make more videos just
00:49:21.650 00:49:21.660 like this in the very near future take
00:49:23.690 00:49:23.700 care bye for now
00:49:32.650 00:49:32.660 you
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