-
Notifications
You must be signed in to change notification settings - Fork 0
/
en-AU.vtt
214 lines (160 loc) · 7.11 KB
/
en-AU.vtt
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
WEBVTT
Kind: captions
Language: en
00:00:00.000 --> 00:00:01.000
English (AU) (Spoken) [Manually Transcribed Captions]
github.com/WizardTim/WizardTim-captions
00:00:01.000 --> 00:00:06.932
In my last video we had a look at this inductor
which was from an LED bulb that had failed.
00:00:06.932 --> 00:00:11.840
I ended up taking a cross section of this to have a look
inside and it ended up being rather interesting
00:00:11.840 --> 00:00:15.195
so I thought I'd show you some of the ones that
I’ve done in the past.
00:00:15.195 --> 00:00:23.040
Here is a normal metal film resistor you can see the ceramic core that has
been coated in metal and then these slits cut in
00:00:23.040 --> 00:00:25.267
it to adjust the resistance.
00:00:25.267 --> 00:00:31.621
Here is a solid tantalum capacitor,
this one's only been cut one fourth the way through
00:00:31.621 --> 00:00:42.800
Here is a common 1N4001 silicon diode,
here you can see the silicon junction in the middle
with the two copper connections on either side
00:00:43.360 --> 00:00:48.960
there's some sort of conductive adhesive between
these and of course the plastic encapsulation
00:00:49.840 --> 00:00:55.920
This here is a rather interesting silicon
avalanche diode manufactured by Vishay
00:00:56.720 --> 00:01:02.720
this diode is in a sintered glass package which
contains quite a few different metals that have
00:01:02.720 --> 00:01:07.760
been soldered together I’m not exactly sure
why they do everything in this package but it's
00:01:07.760 --> 00:01:13.440
certainly rather interesting, the construction
also explains why this particular diode has a
00:01:13.440 --> 00:01:19.360
surprisingly large leakage current due to light
exposure as you can see the sintered glass package
00:01:19.360 --> 00:01:22.371
connects directly to the silicon die.
00:01:22.371 --> 00:01:35.719
now the particular diode that I’m interested in today is this one here this is a 2CL77 20 killovolt 5 milliamps diode, this one's manufactured by HVGT semiconductor
00:01:35.719 --> 00:01:40.000
and I’m rather interested
to see how this is constructed inside.
00:01:40.000 --> 00:01:43.840
If we take a look at the datasheet
we can see it's a pretty standard
00:01:43.840 --> 00:01:49.600
high voltage silicon rectifier diode and
we can see it's used in circuits such as this
00:01:49.600 --> 00:01:56.560
one here but the applications list air purifiers
negative ion generators and electrostatic voltage
00:01:56.560 --> 00:02:01.600
doubling circuits and I’ve more specifically
seen these before in laser printers quite
00:02:01.600 --> 00:02:08.080
often in the high voltage circuits for the toner
electrostatic stuff but you can often see these in
00:02:08.080 --> 00:02:14.560
low power reasonably low voltage x-ray machines
that mean 20 killovolts of course and of course
00:02:14.560 --> 00:02:20.640
other high-voltage rectifier circuits however I’m
not quite sure how these are manufactured although
00:02:20.640 --> 00:02:27.280
looking more specifically at the datasheet we
can see this here maximum forward voltage drop
00:02:27.280 --> 00:02:33.440
is 45 volts which makes me think this is actually
just a whole bunch of normal silicon dies
00:02:33.440 --> 00:02:39.920
stacked on top of each other in order to reach a
20 killovolt breakdown voltage now in order to do
00:02:39.920 --> 00:02:44.880
the cross section I’m just going to do exactly
the same as I did in that other LED video I’ll
00:02:44.880 --> 00:02:50.960
play it really quickly though so that you can get
an idea. Now I did cut this on a cross section with
00:02:50.960 --> 00:02:56.400
the mould line just in case there was some sort
of a non-symmetrical design but I’m doubting it
00:02:59.600 --> 00:03:17.840
this took quite a while I started off with 250
grit and made my way down to eventually 3000 grit
00:03:30.080 --> 00:03:33.280
a little bit the way through
we can start to see some
00:03:33.280 --> 00:03:39.760
by looks of it bits of copper on one side
of the diode and yet here we go now that
00:03:39.760 --> 00:03:43.360
I’ve sanded the other side down a bit more
we can see that it is actually symmetrical
00:03:44.320 --> 00:03:51.680
sanding it down even further we can start to
make out some of the silicon die can't really see
00:03:51.680 --> 00:03:56.720
exactly what's going on here yet so I’ll sand
it down all the way to halfway through now
00:03:59.200 --> 00:04:04.160
and of course this took quite a while it's it
takes quite a lot of effort to sand these things
00:04:04.160 --> 00:04:09.360
down, eventually I got to halfway through
though and started polishing it with some
00:04:09.360 --> 00:04:13.840
2000 and 3000 grit sandpaper
to make it nice and smooth
00:04:22.640 --> 00:04:27.440
now that I’m down to halfway through and have
polished it it's really obvious now you can see
00:04:27.440 --> 00:04:33.360
the individual lines of the dies so this is
definitely just manufactured through a bunch
00:04:33.360 --> 00:04:40.720
of stack diodes now we can quite clearly make
out the individual silicon dyes and if we count
00:04:40.720 --> 00:04:47.440
them there's 22 of them and of course dividing
the maximum forward voltage drop of 45 volts
00:04:47.440 --> 00:04:54.560
down by 22 we get about 2 volts per silicon die
which doesn't really make sense to me I’d have
00:04:54.560 --> 00:05:02.240
expected it to be 0.5 volts per die or about
that so I’m not sure if these are special or if
00:05:02.240 --> 00:05:07.120
the manufacturer is just being very generous
with their maximum forward voltage drop
00:05:07.120 --> 00:05:11.280
maybe it's under the maximum temperature
or something something I’m not quite sure
00:05:12.000 --> 00:05:16.960
if you do know please leave it in the description
because I can't really find much information about
00:05:16.960 --> 00:05:23.360
how these high voltage diodes work although
I did test later on with a high voltage
00:05:23.360 --> 00:05:29.440
insulation tester and i found that the diode
drop was actually much closer to what i expected
00:05:31.520 --> 00:05:37.440
It's also perfectly feasible that the AliExpress
seller that I bought from either sold me the
00:05:37.440 --> 00:05:46.320
wrong diode intentionally or accidentally or maybe
they even purchased a fake diode unintentionally
00:05:47.120 --> 00:05:56.661
so I’ll just leave you with some other close-up
shots of this and as always thanks for watching