1
00:00:01,280 --> 00:00:12,559
[Music]

2
00:00:14,880 --> 00:00:17,600
good afternoon let's start with oh let's

3
00:00:17,600 --> 00:00:19,520
start with the question how many of you

4
00:00:19,520 --> 00:00:22,240
are musicians

5
00:00:23,119 --> 00:00:24,240
okay

6
00:00:24,240 --> 00:00:28,159
how many of you are programmers

7
00:00:28,240 --> 00:00:29,679
i see

8
00:00:29,679 --> 00:00:34,399
people that join between those so good

9
00:00:35,360 --> 00:00:37,040
yes i'm going to talk about how to build

10
00:00:37,040 --> 00:00:39,200
a laser or maybe

11
00:00:39,200 --> 00:00:40,719
how to spend a lot of time building a

12
00:00:40,719 --> 00:00:43,120
laser harp

13
00:00:43,120 --> 00:00:44,800
we'll see

14
00:00:44,800 --> 00:00:47,919
so what is a laser

15
00:00:48,719 --> 00:00:50,160
pioneered by

16
00:00:50,160 --> 00:00:54,079
as far as i know xiaomi shazar in 1982

17
00:00:54,079 --> 00:00:56,719
it's a device that when you hit

18
00:00:56,719 --> 00:01:00,000
a laser something sounds

19
00:01:00,000 --> 00:01:02,320
that's all

20
00:01:02,320 --> 00:01:04,000
it's mainly used for live performances

21
00:01:04,000 --> 00:01:05,920
because you can make a really big show

22
00:01:05,920 --> 00:01:07,200
about it

23
00:01:07,200 --> 00:01:08,960
and that's exactly what we wanted for

24
00:01:08,960 --> 00:01:11,200
but let's talk about how did we get here

25
00:01:11,200 --> 00:01:13,520
first

26
00:01:13,520 --> 00:01:16,880
who am i uh yeah i'm standing on stage

27
00:01:16,880 --> 00:01:19,280
you're not

28
00:01:19,280 --> 00:01:21,520
i used to do a lot of talking on topics

29
00:01:21,520 --> 00:01:23,040
like linux

30
00:01:23,040 --> 00:01:26,159
and open source and embedded

31
00:01:26,159 --> 00:01:30,479
i stopped doing that about 10 years ago

32
00:01:30,479 --> 00:01:33,040
but every now and then it itches so i

33
00:01:33,040 --> 00:01:34,640
have a personal project that i want to

34
00:01:34,640 --> 00:01:37,840
talk about so here i am

35
00:01:39,520 --> 00:01:42,000
more important who are we making this

36
00:01:42,000 --> 00:01:43,680
thing for so there's something called

37
00:01:43,680 --> 00:01:46,320
the sin cecilia progressionist group

38
00:01:46,320 --> 00:01:48,159
leaves out maria out and for everybody

39
00:01:48,159 --> 00:01:50,000
who's not from around there are two

40
00:01:50,000 --> 00:01:52,720
small villages near eindhoven

41
00:01:52,720 --> 00:01:54,640
the southern one lies out is mostly

42
00:01:54,640 --> 00:01:56,479
known for a very big brewery called

43
00:01:56,479 --> 00:01:58,719
bavaria

44
00:01:58,719 --> 00:02:01,119
the northern one maria haute is a really

45
00:02:01,119 --> 00:02:03,520
tiny village mostly known for a singer

46
00:02:03,520 --> 00:02:06,840
called khrushmeowis who was born

47
00:02:06,840 --> 00:02:11,680
there but they also have a very good uh

48
00:02:11,680 --> 00:02:12,879
music

49
00:02:12,879 --> 00:02:15,599
association so assistant cecilia has a

50
00:02:15,599 --> 00:02:17,599
harmony where they

51
00:02:17,599 --> 00:02:20,239
together make a lot of uh well musical

52
00:02:20,239 --> 00:02:22,480
music and they have a practitioners

53
00:02:22,480 --> 00:02:24,160
group where they

54
00:02:24,160 --> 00:02:26,319
use drums and other

55
00:02:26,319 --> 00:02:30,519
things so let's introduce that

56
00:02:32,400 --> 00:02:39,099
[Music]

57
00:02:43,920 --> 00:02:46,319
and now ladies and gentlemen it's time

58
00:02:46,319 --> 00:02:47,440
to meet

59
00:02:47,440 --> 00:02:50,959
the record-breaking history making

60
00:02:50,959 --> 00:02:53,850
16 times

61
00:02:53,850 --> 00:03:14,940
[Music]

62
00:03:14,940 --> 00:03:19,060
[Applause]

63
00:03:22,390 --> 00:03:23,920
[Music]

64
00:03:23,920 --> 00:03:25,040
we

65
00:03:25,040 --> 00:03:28,040
will

66
00:03:46,220 --> 00:03:49,310
[Music]

67
00:04:17,199 --> 00:04:20,199
don't

68
00:04:20,399 --> 00:04:32,240
[Music]

69
00:04:32,560 --> 00:04:34,200
do

70
00:04:34,200 --> 00:04:42,389
[Music]

71
00:04:45,220 --> 00:04:47,520
[Music]

72
00:04:47,520 --> 00:04:49,160
so

73
00:04:49,160 --> 00:05:16,880
[Music]

74
00:05:16,880 --> 00:05:19,880
so

75
00:05:24,000 --> 00:05:26,320
so this was an excerpt from a two and a

76
00:05:26,320 --> 00:05:29,199
half hour show that they did a few weeks

77
00:05:29,199 --> 00:05:30,800
ago

78
00:05:30,800 --> 00:05:32,479
and as you can tell

79
00:05:32,479 --> 00:05:34,479
these guys don't just live for the music

80
00:05:34,479 --> 00:05:36,720
they also live for the show

81
00:05:36,720 --> 00:05:38,240
so it would be nice to have an

82
00:05:38,240 --> 00:05:40,400
instrument that really is just about a

83
00:05:40,400 --> 00:05:42,240
show and a laser harp is such an

84
00:05:42,240 --> 00:05:44,639
instrument

85
00:05:44,960 --> 00:05:47,600
so who's pascal the guy that is missing

86
00:05:47,600 --> 00:05:50,400
here because he is actually with the

87
00:05:50,400 --> 00:05:53,600
youth group of the

88
00:05:53,600 --> 00:05:56,400
music association they're on a trip like

89
00:05:56,400 --> 00:05:58,400
this right now

90
00:05:58,400 --> 00:06:00,400
so we decided that i would come along

91
00:06:00,400 --> 00:06:01,520
but

92
00:06:01,520 --> 00:06:03,680
he's the son of my girlfriend

93
00:06:03,680 --> 00:06:05,440
he is the light

94
00:06:05,440 --> 00:06:07,759
and audio brain behind the percussionist

95
00:06:07,759 --> 00:06:09,440
group so all the lights that you saw for

96
00:06:09,440 --> 00:06:12,160
example in this first part of the video

97
00:06:12,160 --> 00:06:14,000
all the lights coming up it's his

98
00:06:14,000 --> 00:06:15,759
equipment and he did the programming to

99
00:06:15,759 --> 00:06:19,080
make it work

100
00:06:20,960 --> 00:06:23,440
but a laser arm so why well because

101
00:06:23,440 --> 00:06:27,280
perkins group wants it how uh you can

102
00:06:27,280 --> 00:06:29,759
buy one you can rent one or you can make

103
00:06:29,759 --> 00:06:32,400
one and again i made the wrong decision

104
00:06:32,400 --> 00:06:35,840
to say let's make one

105
00:06:37,280 --> 00:06:39,680
so let's talk about how i made one by

106
00:06:39,680 --> 00:06:41,600
trying to save the association a lot of

107
00:06:41,600 --> 00:06:44,240
money because buying is really really

108
00:06:44,240 --> 00:06:47,240
expensive

109
00:06:49,039 --> 00:06:50,960
let's take a brief look at how xiaomi

110
00:06:50,960 --> 00:06:54,780
choja operates such a device

111
00:06:54,780 --> 00:07:01,559
[Applause]

112
00:07:03,360 --> 00:07:07,110
[Music]

113
00:07:14,420 --> 00:07:35,920
[Music]

114
00:07:36,639 --> 00:07:38,560
so let's talk about how does such a

115
00:07:38,560 --> 00:07:40,960
device work we start with the

116
00:07:40,960 --> 00:07:42,639
circle at the top

117
00:07:42,639 --> 00:07:45,840
yeah that's a laser beam

118
00:07:45,919 --> 00:07:48,720
they use green for a reason because it's

119
00:07:48,720 --> 00:07:50,720
the most visible

120
00:07:50,720 --> 00:07:52,720
i have two laser

121
00:07:52,720 --> 00:07:55,759
buttons one is red one is green

122
00:07:55,759 --> 00:07:57,360
probably won't work because it's too

123
00:07:57,360 --> 00:07:59,360
light here anyway but good luck finding

124
00:07:59,360 --> 00:08:01,919
the red one

125
00:08:02,319 --> 00:08:03,199
it's

126
00:08:03,199 --> 00:08:04,639
red is

127
00:08:04,639 --> 00:08:06,319
what is used for laser points all over

128
00:08:06,319 --> 00:08:07,919
the world but it's hardly visible green

129
00:08:07,919 --> 00:08:09,520
is way way way more visible with the

130
00:08:09,520 --> 00:08:13,840
same amount of power put into it

131
00:08:14,240 --> 00:08:16,000
so if you want to make a laser arp jeep

132
00:08:16,000 --> 00:08:18,560
use green

133
00:08:18,560 --> 00:08:20,639
the next thing i want to talk about is

134
00:08:20,639 --> 00:08:22,319
the circle at the bottom

135
00:08:22,319 --> 00:08:25,280
there's only one laser in his design

136
00:08:25,280 --> 00:08:28,080
that is use well i'll show later but

137
00:08:28,080 --> 00:08:31,520
it's using a rotating mirror to come up

138
00:08:31,520 --> 00:08:35,598
with seven big of nine big lasers

139
00:08:37,440 --> 00:08:38,958
this one

140
00:08:38,958 --> 00:08:40,399
hard to see

141
00:08:40,399 --> 00:08:42,799
there's the eye that actually records

142
00:08:42,799 --> 00:08:45,440
the reflection from somebody hitting the

143
00:08:45,440 --> 00:08:47,760
laser

144
00:08:47,760 --> 00:08:49,760
more importantly

145
00:08:49,760 --> 00:08:52,320
that i needs to record only green light

146
00:08:52,320 --> 00:08:54,000
which is why there is no other green

147
00:08:54,000 --> 00:08:56,560
light on the stage very back in the back

148
00:08:56,560 --> 00:08:59,040
you will see blue light

149
00:08:59,040 --> 00:09:02,399
mr jar himself is shown in red light

150
00:09:02,399 --> 00:09:03,440
because

151
00:09:03,440 --> 00:09:05,680
red and green are rather far apart in

152
00:09:05,680 --> 00:09:07,680
the light spectrum so

153
00:09:07,680 --> 00:09:10,000
your regular photodiode will only pick

154
00:09:10,000 --> 00:09:11,760
up green or will only pick up red but

155
00:09:11,760 --> 00:09:14,000
not both

156
00:09:14,000 --> 00:09:16,080
and he is wearing shoes

157
00:09:16,080 --> 00:09:17,680
gloves

158
00:09:17,680 --> 00:09:19,440
just to make sure that he reflects as

159
00:09:19,440 --> 00:09:21,680
much light as possible

160
00:09:21,680 --> 00:09:24,080
so we have an easy job as programmers

161
00:09:24,080 --> 00:09:25,760
actually distinguishing between no light

162
00:09:25,760 --> 00:09:28,560
and reflected light

163
00:09:28,560 --> 00:09:30,560
and at the top his head he is wearing

164
00:09:30,560 --> 00:09:33,680
glasses sunglasses for a reason those

165
00:09:33,680 --> 00:09:37,719
lasers tend to hurt

166
00:09:41,120 --> 00:09:43,200
wrong one

167
00:09:43,200 --> 00:09:46,640
this one so how does it work well

168
00:09:46,640 --> 00:09:49,600
we have a guy he's standing over there

169
00:09:49,600 --> 00:09:53,120
and as soon as he hits the laser button

170
00:09:53,120 --> 00:09:54,880
it will reflect the reflection will go

171
00:09:54,880 --> 00:09:56,640
into the eye and then we need some

172
00:09:56,640 --> 00:09:58,640
electronics to hook up the laser to the

173
00:09:58,640 --> 00:10:00,000
eye

174
00:10:00,000 --> 00:10:01,440
as soon as we

175
00:10:01,440 --> 00:10:04,079
discover okay there is a reflection and

176
00:10:04,079 --> 00:10:06,399
i know which of the beams it was i can

177
00:10:06,399 --> 00:10:09,839
play a note on the synthesizer

178
00:10:09,920 --> 00:10:11,200
is that uh

179
00:10:11,200 --> 00:10:13,760
no okay

180
00:10:14,079 --> 00:10:16,000
so if anyone also asks questions in

181
00:10:16,000 --> 00:10:17,600
between please go ahead i'm used to

182
00:10:17,600 --> 00:10:20,880
getting questions throughout my talk

183
00:10:20,880 --> 00:10:23,600
so don't worry i won't bite

184
00:10:23,600 --> 00:10:24,399
yes

185
00:10:24,399 --> 00:10:26,160
you may want to walk into the microphone

186
00:10:26,160 --> 00:10:28,160
indeed oh there's a walking okay that

187
00:10:28,160 --> 00:10:29,330
also

188
00:10:29,330 --> 00:10:30,839
[Music]

189
00:10:30,839 --> 00:10:34,079
works no

190
00:10:42,079 --> 00:10:44,160
try again yes it works

191
00:10:44,160 --> 00:10:46,720
um how does the eye define the position

192
00:10:46,720 --> 00:10:48,959
and basically how does the eye define

193
00:10:48,959 --> 00:10:51,600
which laser beam was touched

194
00:10:51,600 --> 00:10:53,200
that's all my next slide thank you for

195
00:10:53,200 --> 00:10:56,800
the transitioning to my next slide

196
00:10:59,600 --> 00:11:01,839
oh

197
00:11:02,399 --> 00:11:04,560
no we i story i start at the back one

198
00:11:04,560 --> 00:11:07,119
more slide

199
00:11:07,200 --> 00:11:08,640
so we start at the back doing a

200
00:11:08,640 --> 00:11:11,040
synthesizer means well essentially we

201
00:11:11,040 --> 00:11:13,279
plan to use an arduino to do it so we

202
00:11:13,279 --> 00:11:15,360
need to get a midi signal out of the

203
00:11:15,360 --> 00:11:17,839
arduino into the synthesizer

204
00:11:17,839 --> 00:11:20,160
that turns out to be a solved problem

205
00:11:20,160 --> 00:11:22,640
that was good news for me i already was

206
00:11:22,640 --> 00:11:26,079
envisioning myself really having to

207
00:11:26,079 --> 00:11:28,560
start writing serial

208
00:11:28,560 --> 00:11:31,040
port drivers all over again something i

209
00:11:31,040 --> 00:11:33,600
stopped doing in the 2000s early 2000s

210
00:11:33,600 --> 00:11:35,120
so

211
00:11:35,120 --> 00:11:36,720
i really wasn't fencing doing that again

212
00:11:36,720 --> 00:11:38,399
but fortunately somebody did and it

213
00:11:38,399 --> 00:11:39,820
works

214
00:11:39,820 --> 00:11:48,850
[Music]

215
00:11:50,800 --> 00:11:53,600
so how to detect which

216
00:11:53,600 --> 00:11:56,079
beam is being hit so the first thing and

217
00:11:56,079 --> 00:11:58,320
this is the one that's actually used by

218
00:11:58,320 --> 00:12:00,959
jar and also by quite a few other videos

219
00:12:00,959 --> 00:12:03,200
that i found on youtube is you have a

220
00:12:03,200 --> 00:12:06,240
laser you have a rotating mirror

221
00:12:06,240 --> 00:12:09,200
and you only shoot at specific times

222
00:12:09,200 --> 00:12:10,800
when you know that the

223
00:12:10,800 --> 00:12:14,319
mirror is at a certain position

224
00:12:16,000 --> 00:12:18,800
so you know which where the laser is you

225
00:12:18,800 --> 00:12:20,959
know

226
00:12:21,200 --> 00:12:23,360
if you see a reflection that that that

227
00:12:23,360 --> 00:12:27,279
position so that is the note to talk

228
00:12:31,360 --> 00:12:34,880
we thought about this hard because

229
00:12:34,880 --> 00:12:37,920
pascal owning an audio visual company he

230
00:12:37,920 --> 00:12:40,560
has such a laser he has those mirrors so

231
00:12:40,560 --> 00:12:42,959
he can easily just make that beam not a

232
00:12:42,959 --> 00:12:45,200
problem standard functionality of all

233
00:12:45,200 --> 00:12:48,240
those devices anyway

234
00:12:48,480 --> 00:12:50,240
the lasers themselves are very expensive

235
00:12:50,240 --> 00:12:52,000
we're talking about a few

236
00:12:52,000 --> 00:12:54,480
thousand dollars for a full device or a

237
00:12:54,480 --> 00:12:56,399
few hundred dollars if you talk about

238
00:12:56,399 --> 00:12:58,160
just the laser and then you have to

239
00:12:58,160 --> 00:13:00,639
still do everything yourself

240
00:13:00,639 --> 00:13:01,839
um

241
00:13:01,839 --> 00:13:03,279
also then we're talking about lasers of

242
00:13:03,279 --> 00:13:06,240
100 milliwatts so just watching such a

243
00:13:06,240 --> 00:13:09,839
laser without it being filtered or

244
00:13:09,839 --> 00:13:12,240
being reduced

245
00:13:12,240 --> 00:13:14,160
will just blow your eye away not a

246
00:13:14,160 --> 00:13:16,880
problem it's gone

247
00:13:16,880 --> 00:13:18,800
so we decided let's not build that

248
00:13:18,800 --> 00:13:21,360
ourselves and we could not tap well

249
00:13:21,360 --> 00:13:23,680
enough into those devices to get the

250
00:13:23,680 --> 00:13:25,920
position information out of it

251
00:13:25,920 --> 00:13:30,240
so okay let's go for something simpler

252
00:13:30,240 --> 00:13:33,880
so we bought

253
00:13:34,079 --> 00:13:35,839
several of these cheap

254
00:13:35,839 --> 00:13:38,320
lasers

255
00:13:38,639 --> 00:13:41,040
and we decided okay let's do just this

256
00:13:41,040 --> 00:13:43,920
so we take eight and we turn them on one

257
00:13:43,920 --> 00:13:46,399
at a time

258
00:13:47,040 --> 00:13:50,000
there's one any time the problem

259
00:13:50,000 --> 00:13:51,680
and that is that

260
00:13:51,680 --> 00:13:53,199
at that point we're talking a five

261
00:13:53,199 --> 00:13:54,959
milliwatt laser

262
00:13:54,959 --> 00:13:57,920
that is on one eight of the time versus

263
00:13:57,920 --> 00:13:59,440
a hundred milliwatt or two hundred

264
00:13:59,440 --> 00:14:01,600
milliwatt laser

265
00:14:01,600 --> 00:14:03,519
at the same time so our laser would not

266
00:14:03,519 --> 00:14:04,720
compare

267
00:14:04,720 --> 00:14:08,079
in the light intensity

268
00:14:08,240 --> 00:14:08,959
to

269
00:14:08,959 --> 00:14:10,720
that professional laser and that means

270
00:14:10,720 --> 00:14:12,480
that if you are in the audience and i

271
00:14:12,480 --> 00:14:15,040
have a laser that blows up in smoke my

272
00:14:15,040 --> 00:14:17,279
laser will not be visible enough so you

273
00:14:17,279 --> 00:14:19,519
don't even have the idea that you you

274
00:14:19,519 --> 00:14:21,519
will just see somebody doing this and by

275
00:14:21,519 --> 00:14:23,920
accident notes happen

276
00:14:23,920 --> 00:14:25,279
actually you'll see me do that in the

277
00:14:25,279 --> 00:14:26,399
end

278
00:14:26,399 --> 00:14:28,639
okay

279
00:14:29,120 --> 00:14:30,959
there's a trick around this

280
00:14:30,959 --> 00:14:33,440
that we came up after

281
00:14:33,440 --> 00:14:36,079
a few days of thinking and that is let's

282
00:14:36,079 --> 00:14:37,760
turn it around let's detect when the

283
00:14:37,760 --> 00:14:40,399
laser is off

284
00:14:40,399 --> 00:14:42,639
which means that about 7 8 of

285
00:14:42,639 --> 00:14:46,240
the time the laser is bright and shiny

286
00:14:46,240 --> 00:14:47,920
and only one eighth of the time the

287
00:14:47,920 --> 00:14:51,440
laser is off so i now just want seven

288
00:14:51,440 --> 00:14:53,279
times the amount of intensity of my

289
00:14:53,279 --> 00:14:54,480
laser

290
00:14:54,480 --> 00:14:56,639
and now i'm at the same level as that

291
00:14:56,639 --> 00:14:59,839
hundred milliwatt laser is

292
00:15:00,639 --> 00:15:02,480
so we bought a few of those

293
00:15:02,480 --> 00:15:04,959
and we started experimenting like okay i

294
00:15:04,959 --> 00:15:07,199
push the button

295
00:15:07,199 --> 00:15:08,800
and i have my arduino on the other end

296
00:15:08,800 --> 00:15:11,279
and i check is the light coming up in

297
00:15:11,279 --> 00:15:13,839
one go and at the end is going down in

298
00:15:13,839 --> 00:15:15,839
one go because if it would for example

299
00:15:15,839 --> 00:15:18,320
come up go down go up go down come up

300
00:15:18,320 --> 00:15:19,920
then i need to accommodate for that

301
00:15:19,920 --> 00:15:21,839
period because that makes it very

302
00:15:21,839 --> 00:15:24,240
unreliable to detect a note

303
00:15:24,240 --> 00:15:26,560
same is true at the end if it takes

304
00:15:26,560 --> 00:15:29,920
eons to go down

305
00:15:29,920 --> 00:15:31,440
then i need to take that into account

306
00:15:31,440 --> 00:15:33,759
when making my cycle for turning on and

307
00:15:33,759 --> 00:15:37,040
off the lasers so

308
00:15:37,360 --> 00:15:39,199
we figured out that there's no startup

309
00:15:39,199 --> 00:15:42,240
or end effects

310
00:15:42,240 --> 00:15:44,800
that's great

311
00:15:46,639 --> 00:15:48,880
so we bought seven more and thought we

312
00:15:48,880 --> 00:15:51,360
could start

313
00:15:52,839 --> 00:15:55,759
sorry does this work yeah oh

314
00:15:55,759 --> 00:15:58,320
sorry i wasn't paying attention yes um

315
00:15:58,320 --> 00:16:01,120
it seemed obvious to me that you could

316
00:16:01,120 --> 00:16:05,279
have used the laser rangefinders

317
00:16:05,279 --> 00:16:07,120
for detecting

318
00:16:07,120 --> 00:16:10,639
which beam was like covered

319
00:16:11,839 --> 00:16:12,800
lazier

320
00:16:12,800 --> 00:16:15,040
rangefinder you know they are used on

321
00:16:15,040 --> 00:16:18,079
the building sites to measure the range

322
00:16:18,079 --> 00:16:20,880
from the device to the wall whatever

323
00:16:20,880 --> 00:16:22,480
yes i could

324
00:16:22,480 --> 00:16:24,560
that's a rather complicated device

325
00:16:24,560 --> 00:16:25,440
though

326
00:16:25,440 --> 00:16:27,360
because it means that you have

327
00:16:27,360 --> 00:16:30,480
a laser going out

328
00:16:31,120 --> 00:16:32,800
and then it reflects against the wall

329
00:16:32,800 --> 00:16:34,959
and it comes back

330
00:16:34,959 --> 00:16:36,720
and then you have to measure the time of

331
00:16:36,720 --> 00:16:39,040
flight

332
00:16:39,040 --> 00:16:40,800
we're talking

333
00:16:40,800 --> 00:16:43,199
microseconds that is very complicated

334
00:16:43,199 --> 00:16:44,800
electronics to get right if you are a

335
00:16:44,800 --> 00:16:47,359
hobbyist

336
00:16:48,320 --> 00:16:51,320
okay

337
00:16:52,480 --> 00:16:55,279
um i built a laser harp myself with that

338
00:16:55,279 --> 00:16:57,199
like with time of flight sensors you can

339
00:16:57,199 --> 00:17:00,399
get them for i think under 10 bucks so

340
00:17:00,399 --> 00:17:02,000
it's a really good recommendation so

341
00:17:02,000 --> 00:17:04,160
then you are really measuring where is

342
00:17:04,160 --> 00:17:06,799
the hand yeah yeah okay we can talk

343
00:17:06,799 --> 00:17:08,640
about it later yes please

344
00:17:08,640 --> 00:17:10,240
you would solve a second problem that i

345
00:17:10,240 --> 00:17:11,919
still need to talk about i brought it

346
00:17:11,919 --> 00:17:12,959
with me

347
00:17:12,959 --> 00:17:15,199
cool

348
00:17:17,039 --> 00:17:19,280
um this is what i'd hoped for that

349
00:17:19,280 --> 00:17:22,959
people would start giving me ideas

350
00:17:23,839 --> 00:17:26,160
so these laser harps are cheap really

351
00:17:26,160 --> 00:17:27,199
cheap

352
00:17:27,199 --> 00:17:30,160
obviously made in china and

353
00:17:30,160 --> 00:17:32,960
um

354
00:17:32,960 --> 00:17:34,799
we learned that they were made in china

355
00:17:34,799 --> 00:17:37,600
very the hard way because for example

356
00:17:37,600 --> 00:17:40,240
if you screw them together

357
00:17:40,240 --> 00:17:42,799
that won't always work

358
00:17:42,799 --> 00:17:45,679
they're really machined so poorly that

359
00:17:45,679 --> 00:17:48,480
the screwed thread on it is not

360
00:17:48,480 --> 00:17:51,840
necessarily working correctly

361
00:17:51,840 --> 00:17:54,640
the batteries don't always fit

362
00:17:54,640 --> 00:17:57,200
the laser is not exactly in the middle

363
00:17:57,200 --> 00:18:00,400
of the tube

364
00:18:00,400 --> 00:18:03,840
i wish i had bought three more

365
00:18:03,840 --> 00:18:05,679
that would have made it much better but

366
00:18:05,679 --> 00:18:07,360
we had enough that were reasonably

367
00:18:07,360 --> 00:18:10,799
usable so we continued

368
00:18:12,720 --> 00:18:14,320
so i only want to use the top half i

369
00:18:14,320 --> 00:18:16,160
don't want to use the batteries and that

370
00:18:16,160 --> 00:18:17,919
means that i need the mechanism to push

371
00:18:17,919 --> 00:18:20,559
the buttons

372
00:18:20,960 --> 00:18:23,360
so my first device so fortunately i have

373
00:18:23,360 --> 00:18:25,840
a 3d printer so i made

374
00:18:25,840 --> 00:18:27,440
some kind of

375
00:18:27,440 --> 00:18:29,039
mechanism that would grab it and i could

376
00:18:29,039 --> 00:18:32,000
use a screw to fasten and unfasten

377
00:18:32,000 --> 00:18:33,760
turned out to be too hard so we did the

378
00:18:33,760 --> 00:18:36,960
same thing with tie wraps

379
00:18:37,600 --> 00:18:39,918
worked

380
00:18:40,960 --> 00:18:42,480
but

381
00:18:42,480 --> 00:18:46,559
kind of intricate to design if you

382
00:18:46,559 --> 00:18:47,600
oh

383
00:18:47,600 --> 00:18:49,760
that

384
00:18:52,000 --> 00:18:54,240
other story first

385
00:18:54,240 --> 00:18:56,799
but then i st because i still have that

386
00:18:56,799 --> 00:18:59,440
other end right so what you see here

387
00:18:59,440 --> 00:19:01,520
at the bottom one is that i we just

388
00:19:01,520 --> 00:19:04,240
soldered the wires and then you need to

389
00:19:04,240 --> 00:19:07,120
keep in mind that there's a spring

390
00:19:07,120 --> 00:19:09,200
to push against the batteries that you

391
00:19:09,200 --> 00:19:11,360
need to solder again spring is not

392
00:19:11,360 --> 00:19:13,600
standard metal so soldering doesn't

393
00:19:13,600 --> 00:19:15,520
really stick

394
00:19:15,520 --> 00:19:18,480
and on the inside of the tube is

395
00:19:18,480 --> 00:19:19,840
a brass

396
00:19:19,840 --> 00:19:21,840
ring that contains the thread and that's

397
00:19:21,840 --> 00:19:23,840
also not really nice soldering against

398
00:19:23,840 --> 00:19:27,120
so that it didn't really stick well

399
00:19:27,120 --> 00:19:28,720
and because we wanted this to be at

400
00:19:28,720 --> 00:19:32,240
least a little bit sturdy

401
00:19:35,039 --> 00:19:37,200
i 3d printed a

402
00:19:37,200 --> 00:19:38,799
small piece

403
00:19:38,799 --> 00:19:40,320
and i would hook it up together like

404
00:19:40,320 --> 00:19:42,559
this

405
00:19:44,160 --> 00:19:47,039
so the screw is on the top that will

406
00:19:47,039 --> 00:19:49,120
push against the

407
00:19:49,120 --> 00:19:50,720
spring

408
00:19:50,720 --> 00:19:52,240
and i have the wire on the other end

409
00:19:52,240 --> 00:19:53,679
that will just

410
00:19:53,679 --> 00:19:56,080
spread itself out and fill up the room

411
00:19:56,080 --> 00:19:59,199
that the thread gives

412
00:20:00,160 --> 00:20:02,640
so this was

413
00:20:02,640 --> 00:20:04,880
immediately spot on this

414
00:20:04,880 --> 00:20:06,640
we did this only once and they have been

415
00:20:06,640 --> 00:20:08,000
on since

416
00:20:08,000 --> 00:20:10,000
connection is really reliable even if we

417
00:20:10,000 --> 00:20:14,400
drop it etc so this was a good decision

418
00:20:15,919 --> 00:20:19,200
then we need to put a together

419
00:20:19,200 --> 00:20:21,360
that was quite quite an intricate design

420
00:20:21,360 --> 00:20:23,760
to make because the angles

421
00:20:23,760 --> 00:20:26,080
need to well yeah

422
00:20:26,080 --> 00:20:28,080
took me quite a lot of youtube reading

423
00:20:28,080 --> 00:20:31,360
and viewing to see how to wire all

424
00:20:31,360 --> 00:20:33,919
the stuff up together in fusion 360 but

425
00:20:33,919 --> 00:20:35,679
i got it done and this is actually the

426
00:20:35,679 --> 00:20:37,760
first time i printed it it was right the

427
00:20:37,760 --> 00:20:39,280
first time

428
00:20:39,280 --> 00:20:41,280
until i realized that one of my lasers

429
00:20:41,280 --> 00:20:43,200
is off center

430
00:20:43,200 --> 00:20:45,200
so i technically need to make a new one

431
00:20:45,200 --> 00:20:46,799
where i put one of the lasers slightly

432
00:20:46,799 --> 00:20:49,799
tilted

433
00:20:59,200 --> 00:21:02,000
then we have that small problem of

434
00:21:02,000 --> 00:21:05,200
switching the lasers

435
00:21:05,760 --> 00:21:08,000
solved problem

436
00:21:08,000 --> 00:21:09,280
except that the

437
00:21:09,280 --> 00:21:11,280
transistor i wanted to use well mosfet i

438
00:21:11,280 --> 00:21:13,280
wanted to use for that actually is out

439
00:21:13,280 --> 00:21:14,960
of stock at for now

440
00:21:14,960 --> 00:21:17,520
any variant any amount they're out of

441
00:21:17,520 --> 00:21:20,799
stock wait what

442
00:21:23,919 --> 00:21:25,840
locally

443
00:21:25,840 --> 00:21:27,840
my local electronic shop still had them

444
00:21:27,840 --> 00:21:30,720
so i could buy 10 of them but

445
00:21:30,720 --> 00:21:32,799
that was kind of a setback because i was

446
00:21:32,799 --> 00:21:34,960
expecting to buy them in bulk

447
00:21:34,960 --> 00:21:40,679
but i have 10. ok i need 8 that's good

448
00:21:46,400 --> 00:21:49,360
then the most painful part started

449
00:21:49,360 --> 00:21:51,840
so i love to talk about those

450
00:21:51,840 --> 00:21:54,959
time-of-flight sensors

451
00:21:55,520 --> 00:21:56,799
we

452
00:21:56,799 --> 00:21:58,480
thought that we could just use standard

453
00:21:58,480 --> 00:22:01,360
photodiodes

454
00:22:03,039 --> 00:22:05,280
and they should be

455
00:22:05,280 --> 00:22:07,120
after i reflect a lot of light so they

456
00:22:07,120 --> 00:22:08,880
should be able to see that reflection of

457
00:22:08,880 --> 00:22:12,039
the light

458
00:22:12,400 --> 00:22:13,600
um

459
00:22:13,600 --> 00:22:15,360
they should be they only mostly

460
00:22:15,360 --> 00:22:17,039
sensitive to green light

461
00:22:17,039 --> 00:22:19,200
there's a big contrast between no light

462
00:22:19,200 --> 00:22:21,520
and yes light so it should not be a

463
00:22:21,520 --> 00:22:23,840
problem

464
00:22:24,880 --> 00:22:26,640
and just to make sure that we got it

465
00:22:26,640 --> 00:22:29,440
right we i made some kind of cone around

466
00:22:29,440 --> 00:22:31,280
it so they would not see any false light

467
00:22:31,280 --> 00:22:33,280
coming in from the stage lights or from

468
00:22:33,280 --> 00:22:34,960
the audience that happens to make

469
00:22:34,960 --> 00:22:37,679
pictures or whatever

470
00:22:37,679 --> 00:22:39,360
of course then i learned that printing

471
00:22:39,360 --> 00:22:41,600
them in white plastic is not a good idea

472
00:22:41,600 --> 00:22:44,240
because that is just as translucent as

473
00:22:44,240 --> 00:22:46,400
doing nothing so i printed them again in

474
00:22:46,400 --> 00:22:50,240
black plastic which does work

475
00:22:50,880 --> 00:22:53,440
and i decided to use four of them just

476
00:22:53,440 --> 00:22:55,600
to make sure that i can tune them as

477
00:22:55,600 --> 00:22:58,240
close as possible to two of my lasers so

478
00:22:58,240 --> 00:23:00,720
just make maximize all of it it should

479
00:23:00,720 --> 00:23:03,039
work

480
00:23:03,440 --> 00:23:06,760
no it doesn't

481
00:23:08,880 --> 00:23:13,120
but okay i hook up everything together

482
00:23:15,600 --> 00:23:16,720
oh

483
00:23:16,720 --> 00:23:18,640
if you wonder what those caps are for

484
00:23:18,640 --> 00:23:20,400
just to make sure that i don't actually

485
00:23:20,400 --> 00:23:23,600
hurt myself

486
00:23:23,600 --> 00:23:24,880
so they're

487
00:23:24,880 --> 00:23:26,559
on the lasers

488
00:23:26,559 --> 00:23:27,840
i hope you can see it in the back as

489
00:23:27,840 --> 00:23:30,000
well they're on the lasers and

490
00:23:30,000 --> 00:23:31,760
if i want to toy i take them off if i

491
00:23:31,760 --> 00:23:33,280
don't want the toy

492
00:23:33,280 --> 00:23:34,799
i just keep them all i know when the

493
00:23:34,799 --> 00:23:36,480
lasers are on because they will light up

494
00:23:36,480 --> 00:23:38,880
nicely

495
00:23:39,200 --> 00:23:40,960
and i think i saved my eyes that way

496
00:23:40,960 --> 00:23:42,400
because i'm pretty sure that at least

497
00:23:42,400 --> 00:23:44,240
twice i was with my head on a location

498
00:23:44,240 --> 00:23:47,200
where i shouldn't have been

499
00:23:49,600 --> 00:23:51,360
programmed the arduino

500
00:23:51,360 --> 00:23:53,200
yes i did

501
00:23:53,200 --> 00:23:55,440
well

502
00:23:55,679 --> 00:23:57,760
i first started coding it on the pc

503
00:23:57,760 --> 00:23:59,840
because we were way ahead with software

504
00:23:59,840 --> 00:24:01,840
compared to hardware

505
00:24:01,840 --> 00:24:05,840
not the average project i've done

506
00:24:06,320 --> 00:24:08,400
so

507
00:24:08,400 --> 00:24:11,279
as i do in my job

508
00:24:11,279 --> 00:24:13,520
and i still have to convince every time

509
00:24:13,520 --> 00:24:15,520
i go out

510
00:24:15,520 --> 00:24:17,200
for my work and convince in a new

511
00:24:17,200 --> 00:24:18,799
project i have to convince the manager

512
00:24:18,799 --> 00:24:21,360
no i want my team to first write the

513
00:24:21,360 --> 00:24:22,320
test

514
00:24:22,320 --> 00:24:24,480
then write the code

515
00:24:24,480 --> 00:24:26,880
write a new test write new code write

516
00:24:26,880 --> 00:24:29,039
test write code write test write code

517
00:24:29,039 --> 00:24:31,840
test driven design

518
00:24:31,840 --> 00:24:33,679
executed

519
00:24:33,679 --> 00:24:35,440
and i actually say i want two

520
00:24:35,440 --> 00:24:37,360
programmers on each job

521
00:24:37,360 --> 00:24:39,039
give them two keyboards hooked up to the

522
00:24:39,039 --> 00:24:41,679
same pc

523
00:24:42,320 --> 00:24:43,919
so then you actually get the mechanics

524
00:24:43,919 --> 00:24:45,600
where you have one programmer writing a

525
00:24:45,600 --> 00:24:47,120
small test

526
00:24:47,120 --> 00:24:50,320
probably the first test is going to be

527
00:24:50,320 --> 00:24:51,919
is the class that we're going to build

528
00:24:51,919 --> 00:24:56,240
does it exist so just instantiate class

529
00:24:56,240 --> 00:24:58,640
test fails doesn't compile the other guy

530
00:24:58,640 --> 00:25:01,039
comes in types

531
00:25:01,039 --> 00:25:02,480
i have a class

532
00:25:02,480 --> 00:25:05,039
test works he writes the next test

533
00:25:05,039 --> 00:25:07,440
he writes the next code and so they keep

534
00:25:07,440 --> 00:25:09,200
working together they keep one offering

535
00:25:09,200 --> 00:25:11,679
each other because you very quickly find

536
00:25:11,679 --> 00:25:12,400
that

537
00:25:12,400 --> 00:25:14,400
two programmers working on the same

538
00:25:14,400 --> 00:25:16,320
pc with the same velvet separate

539
00:25:16,320 --> 00:25:17,360
keyboards

540
00:25:17,360 --> 00:25:18,960
are trying to

541
00:25:18,960 --> 00:25:22,799
be smarter than the other guy so

542
00:25:22,799 --> 00:25:25,440
they will test all the weird cases that

543
00:25:25,440 --> 00:25:27,360
could happen i will write code that is

544
00:25:27,360 --> 00:25:31,120
really solid against any misuse

545
00:25:31,120 --> 00:25:33,120
and they will do it in twice the speed

546
00:25:33,120 --> 00:25:37,039
that a normal programmer can write code

547
00:25:37,120 --> 00:25:40,159
actually they are 2.2 times faster than

548
00:25:40,159 --> 00:25:42,799
an average single programmer so

549
00:25:42,799 --> 00:25:45,279
programming with two guys

550
00:25:45,279 --> 00:25:47,360
at the same time is faster than doing it

551
00:25:47,360 --> 00:25:50,080
by yourself

552
00:25:50,400 --> 00:25:52,400
believe me no manager understands that

553
00:25:52,400 --> 00:25:55,520
the first time i explain it

554
00:25:55,520 --> 00:25:58,559
any of you have ever done it that way

555
00:25:58,559 --> 00:26:00,480
pair programming

556
00:26:00,480 --> 00:26:01,760
you did

557
00:26:01,760 --> 00:26:05,600
did it work out for you the same way

558
00:26:06,320 --> 00:26:08,240
you're trying to force my team i did it

559
00:26:08,240 --> 00:26:10,000
works

560
00:26:10,000 --> 00:26:11,039
it works

561
00:26:11,039 --> 00:26:13,760
it works for you

562
00:26:15,919 --> 00:26:17,679
yes you always have to convince people

563
00:26:17,679 --> 00:26:21,039
to stick to the rules yes

564
00:26:22,000 --> 00:26:24,320
yeah so unfortunately they had me as a

565
00:26:24,320 --> 00:26:26,240
software architect slapping everybody in

566
00:26:26,240 --> 00:26:28,000
place so yes they kept following the

567
00:26:28,000 --> 00:26:30,159
rules i made short of that and once you

568
00:26:30,159 --> 00:26:32,480
do it for a week or two it becomes a

569
00:26:32,480 --> 00:26:34,880
second habit and really your team gets

570
00:26:34,880 --> 00:26:37,279
faster

571
00:26:37,360 --> 00:26:39,039
okay so

572
00:26:39,039 --> 00:26:41,200
you should do what you preach so i wrote

573
00:26:41,200 --> 00:26:43,120
my code using tdd

574
00:26:43,120 --> 00:26:45,520
on my pc then i compiled it for the

575
00:26:45,520 --> 00:26:47,360
arduino and realized that arduino did

576
00:26:47,360 --> 00:26:50,320
not have any stl

577
00:26:50,320 --> 00:26:51,279
okay

578
00:26:51,279 --> 00:26:53,520
back to old c style arrays

579
00:26:53,520 --> 00:26:55,360
later i realized that there's also a

580
00:26:55,360 --> 00:26:57,360
plug-in for arduino where you can get

581
00:26:57,360 --> 00:27:00,240
all the stl stuff

582
00:27:00,240 --> 00:27:04,000
but okay yeah software done

583
00:27:04,000 --> 00:27:05,760
actually software was done in

584
00:27:05,760 --> 00:27:07,520
december already and we only did the

585
00:27:07,520 --> 00:27:10,639
hardware in march

586
00:27:12,159 --> 00:27:13,760
so does it work

587
00:27:13,760 --> 00:27:16,640
well almost

588
00:27:18,159 --> 00:27:20,480
so watch the laser with the where the

589
00:27:20,480 --> 00:27:23,440
arrow is pointing you'll find that it

590
00:27:23,440 --> 00:27:25,679
comes so this is just turning a laser on

591
00:27:25,679 --> 00:27:27,200
and off

592
00:27:27,200 --> 00:27:30,240
so let's do it again

593
00:27:31,840 --> 00:27:33,279
so that laser

594
00:27:33,279 --> 00:27:34,799
starts burn

595
00:27:34,799 --> 00:27:37,520
starts and then becomes brighter

596
00:27:37,520 --> 00:27:39,200
we also have another one that is

597
00:27:39,200 --> 00:27:40,640
actually not shown in the video that

598
00:27:40,640 --> 00:27:42,640
after a few seconds will turn less

599
00:27:42,640 --> 00:27:44,880
bright

600
00:27:44,880 --> 00:27:47,039
wow those chinese can make effects into

601
00:27:47,039 --> 00:27:49,840
the lasers

602
00:27:51,679 --> 00:27:52,799
okay

603
00:27:52,799 --> 00:27:55,679
okay okay

604
00:28:00,880 --> 00:28:03,200
let's so this is oh

605
00:28:03,200 --> 00:28:04,880
this is the actual program that i wanted

606
00:28:04,880 --> 00:28:06,880
to use right so i would

607
00:28:06,880 --> 00:28:09,200
have all the lasers on and would disable

608
00:28:09,200 --> 00:28:12,720
the laser that i want to check

609
00:28:13,600 --> 00:28:16,399
and you again if i replay you will see

610
00:28:16,399 --> 00:28:18,240
that

611
00:28:18,240 --> 00:28:19,520
they are

612
00:28:19,520 --> 00:28:23,120
still brightness variations

613
00:28:24,000 --> 00:28:25,360
the good news

614
00:28:25,360 --> 00:28:27,760
and that really saved my day is that if

615
00:28:27,760 --> 00:28:30,960
i go to much faster frequency so really

616
00:28:30,960 --> 00:28:32,320
a lot less

617
00:28:32,320 --> 00:28:34,559
time say only

618
00:28:34,559 --> 00:28:36,960
one millisecond in between each turning

619
00:28:36,960 --> 00:28:39,039
on turning off instead of

620
00:28:39,039 --> 00:28:42,399
the about 100 that it was in this video

621
00:28:42,399 --> 00:28:45,600
all those effects go away mostly

622
00:28:45,600 --> 00:28:47,919
it becomes a lot more equal in

623
00:28:47,919 --> 00:28:50,480
brightness

624
00:28:50,559 --> 00:28:54,520
few almost saved

625
00:29:02,080 --> 00:29:05,039
is this visible

626
00:29:05,039 --> 00:29:07,039
the true lines i drew by

627
00:29:07,039 --> 00:29:09,670
in powerpoint so

628
00:29:09,670 --> 00:29:16,159
[Music]

629
00:29:16,159 --> 00:29:19,159
i

630
00:29:26,960 --> 00:29:28,880
um

631
00:29:28,880 --> 00:29:32,249
[Music]

632
00:29:40,400 --> 00:29:44,080
[Music]

633
00:29:44,080 --> 00:29:47,799
yeah yeah it's good

634
00:29:56,080 --> 00:29:57,360
so

635
00:29:57,360 --> 00:30:00,639
how many notes do you hear

636
00:30:01,360 --> 00:30:03,440
two

637
00:30:03,440 --> 00:30:05,919
i think i heard only one note

638
00:30:05,919 --> 00:30:09,440
played with three different instruments

639
00:30:09,440 --> 00:30:11,919
two of them more or less reliable one of

640
00:30:11,919 --> 00:30:15,440
them plays at random

641
00:30:17,039 --> 00:30:18,799
i have a problem with my detection

642
00:30:18,799 --> 00:30:21,679
mechanism and not a simple one

643
00:30:21,679 --> 00:30:22,799
so

644
00:30:22,799 --> 00:30:25,279
let's talk about time of flight

645
00:30:25,279 --> 00:30:28,799
but um no so conceptually

646
00:30:28,799 --> 00:30:30,240
what i think happens and that's the

647
00:30:30,240 --> 00:30:32,000
stupid mistake we did at the beginning

648
00:30:32,000 --> 00:30:34,480
we did check whether if you power a

649
00:30:34,480 --> 00:30:36,399
laser that it would immediately

650
00:30:36,399 --> 00:30:39,440
just go on and keep burning what we

651
00:30:39,440 --> 00:30:42,320
didn't check is how much time it takes

652
00:30:42,320 --> 00:30:44,399
between actually enabling it and the

653
00:30:44,399 --> 00:30:47,520
first light coming on

654
00:30:47,520 --> 00:30:49,120
i think

655
00:30:49,120 --> 00:30:51,039
that i have only two lasers that are

656
00:30:51,039 --> 00:30:53,120
reasonably fast and the right the rest

657
00:30:53,120 --> 00:30:55,679
is too slow

658
00:30:55,679 --> 00:30:56,799
so

659
00:30:56,799 --> 00:30:58,799
my detection is off

660
00:30:58,799 --> 00:31:00,799
my timing is off

661
00:31:00,799 --> 00:31:02,799
and that is also enforceable by the fact

662
00:31:02,799 --> 00:31:05,120
that when i turned it slow

663
00:31:05,120 --> 00:31:07,600
made this system work slower it would

664
00:31:07,600 --> 00:31:08,880
work

665
00:31:08,880 --> 00:31:11,840
more reliable

666
00:31:11,840 --> 00:31:14,159
the second part that i have three

667
00:31:14,159 --> 00:31:17,519
instruments instead of different nodes

668
00:31:17,519 --> 00:31:20,640
is just my stupidity i misread the midi

669
00:31:20,640 --> 00:31:22,320
protocol

670
00:31:22,320 --> 00:31:24,080
but i was not in the mood to fix it

671
00:31:24,080 --> 00:31:26,480
anymore

672
00:31:26,720 --> 00:31:28,720
and at this time i would have hoped to

673
00:31:28,720 --> 00:31:33,159
power up the board and show it to you

674
00:31:33,360 --> 00:31:35,760
not gonna work here it's way way way too

675
00:31:35,760 --> 00:31:38,640
bright i tried in the speaker tent

676
00:31:38,640 --> 00:31:41,200
briefly

677
00:31:42,000 --> 00:31:45,360
my photo deods just say sorry it's light

678
00:31:45,360 --> 00:31:48,559
i can't get them to be dark

679
00:31:48,559 --> 00:31:51,039
so no actual demo which

680
00:31:51,039 --> 00:31:52,720
i'm sorry it takes five seconds of the

681
00:31:52,720 --> 00:31:55,200
schedule

682
00:31:56,559 --> 00:32:00,120
we're almost there

683
00:32:00,880 --> 00:32:03,360
you saw already from the original vid

684
00:32:03,360 --> 00:32:05,679
video of the drum band that they tend to

685
00:32:05,679 --> 00:32:07,679
perform their shows

686
00:32:07,679 --> 00:32:09,360
in a real stage

687
00:32:09,360 --> 00:32:12,559
where it's dark so we can get it dark

688
00:32:12,559 --> 00:32:14,640
with the smoke with the 5 millivolt

689
00:32:14,640 --> 00:32:18,240
lasers that will work

690
00:32:18,240 --> 00:32:20,000
getting it to be reliable is going to be

691
00:32:20,000 --> 00:32:22,559
the problem

692
00:32:23,440 --> 00:32:25,279
and i believe that to be a solvable

693
00:32:25,279 --> 00:32:27,519
problem and definitely if time of flight

694
00:32:27,519 --> 00:32:30,480
is an achievable thing

695
00:32:30,480 --> 00:32:31,760
but

696
00:32:31,760 --> 00:32:33,919
i still need to check the power to to

697
00:32:33,919 --> 00:32:38,080
light capability of all the lasers

698
00:32:38,159 --> 00:32:40,320
and if i want to check a little bit

699
00:32:40,320 --> 00:32:42,320
about the brightness i want to adjust it

700
00:32:42,320 --> 00:32:44,000
a little bit i need to see if the power

701
00:32:44,000 --> 00:32:45,679
sources make a difference because i

702
00:32:45,679 --> 00:32:48,159
really noticed that if i

703
00:32:48,159 --> 00:32:50,960
power up my power supply more so go from

704
00:32:50,960 --> 00:32:54,480
2.8 up to 3 or 3.4

705
00:32:54,480 --> 00:32:57,200
to 3.4 volts the lasers become much

706
00:32:57,200 --> 00:32:59,760
brighter

707
00:32:59,760 --> 00:33:02,640
so apparently a laser is not a digital

708
00:33:02,640 --> 00:33:04,000
thing

709
00:33:04,000 --> 00:33:06,960
good works for me

710
00:33:07,120 --> 00:33:08,640
um

711
00:33:08,640 --> 00:33:10,159
but that also means that i can make

712
00:33:10,159 --> 00:33:12,000
power supplies per laser and then i can

713
00:33:12,000 --> 00:33:14,000
adjust the brightness um

714
00:33:14,000 --> 00:33:15,440
or

715
00:33:15,440 --> 00:33:17,519
if i don't do the time of flight why not

716
00:33:17,519 --> 00:33:20,240
just take a webcam

717
00:33:20,240 --> 00:33:24,039
and just make a recording

718
00:33:24,960 --> 00:33:27,039
and now i hope there's a music musician

719
00:33:27,039 --> 00:33:29,519
in the room

720
00:33:32,240 --> 00:33:33,440
no

721
00:33:33,440 --> 00:33:38,120
if i take a regular webcam how many

722
00:33:40,480 --> 00:33:42,720
25 frames for

723
00:33:42,720 --> 00:33:45,440
so if i get to 25 frames any

724
00:33:45,440 --> 00:33:47,840
percussionist will hear the delay

725
00:33:47,840 --> 00:33:50,159
between me hitting the beam and the

726
00:33:50,159 --> 00:33:53,279
sound coming off that's way too much so

727
00:33:53,279 --> 00:33:55,279
if i go to 60

728
00:33:55,279 --> 00:33:59,360
we're on the verge of being reliable

729
00:33:59,360 --> 00:34:03,360
at this system i was at 120.

730
00:34:04,880 --> 00:34:06,720
that is beyond we'll take in here so

731
00:34:06,720 --> 00:34:09,119
that's good enough but 25 frames per

732
00:34:09,119 --> 00:34:12,159
second definitely isn't good enough

733
00:34:12,159 --> 00:34:14,079
on the other hand

734
00:34:14,079 --> 00:34:16,159
you saw lastly lars the air drummer at

735
00:34:16,159 --> 00:34:18,639
the beginning right the show

736
00:34:18,639 --> 00:34:20,560
any of you noticed that they faked it

737
00:34:20,560 --> 00:34:23,599
all all of it

738
00:34:24,639 --> 00:34:28,240
they pre-recorded the entire

739
00:34:29,040 --> 00:34:30,879
so he was just rubbing in the air the

740
00:34:30,879 --> 00:34:32,879
guys behind him were faking that they

741
00:34:32,879 --> 00:34:33,760
were

742
00:34:33,760 --> 00:34:35,440
doing the drum effects because it was

743
00:34:35,440 --> 00:34:37,359
all pre-recorded and they were just re

744
00:34:37,359 --> 00:34:39,359
playing a tape

745
00:34:39,359 --> 00:34:40,960
actually they faked me i didn't know

746
00:34:40,960 --> 00:34:42,639
either

747
00:34:42,639 --> 00:34:44,639
i was aware that they were going to do

748
00:34:44,639 --> 00:34:46,399
it i did not know that how they did it

749
00:34:46,399 --> 00:34:48,560
and okay they tricked me so if

750
00:34:48,560 --> 00:34:50,320
everything else fails we'll just

751
00:34:50,320 --> 00:34:52,000
pre-record the laser because somebody

752
00:34:52,000 --> 00:34:54,239
will be hitting but light not a problem

753
00:34:54,239 --> 00:34:57,200
we'll make the show

754
00:35:00,240 --> 00:35:03,839
having said that

755
00:35:03,920 --> 00:35:05,359
we're getting there

756
00:35:05,359 --> 00:35:06,560
slowly

757
00:35:06,560 --> 00:35:08,800
we will get that show next year that's

758
00:35:08,800 --> 00:35:10,960
not a discussion we will have that show

759
00:35:10,960 --> 00:35:12,079
i have my

760
00:35:12,079 --> 00:35:14,560
eight laser beams going up everything

761
00:35:14,560 --> 00:35:17,040
else can be faked

762
00:35:17,040 --> 00:35:19,040
thank you for listening

763
00:35:19,040 --> 00:35:20,560
and i will take more questions if there

764
00:35:20,560 --> 00:35:22,530
are any more questions

765
00:35:22,530 --> 00:35:30,800
[Applause]

766
00:35:30,800 --> 00:35:31,920
i'll go

767
00:35:31,920 --> 00:35:34,560
oh god

768
00:35:34,560 --> 00:35:36,720
i'm trying to imagine how you would play

769
00:35:36,720 --> 00:35:38,560
a chord but i suppose you just take the

770
00:35:38,560 --> 00:35:40,880
low two notes because it's very

771
00:35:40,880 --> 00:35:43,110
difficult to

772
00:35:43,110 --> 00:35:44,960
[Laughter]

773
00:35:44,960 --> 00:35:47,920
okay so the idea was

774
00:35:47,920 --> 00:35:48,800
to

775
00:35:48,800 --> 00:35:51,599
use them in a drum band

776
00:35:51,599 --> 00:35:54,400
so um

777
00:35:54,560 --> 00:35:57,040
most of the even the melodic instruments

778
00:35:57,040 --> 00:35:59,680
in a drum band are still well there are

779
00:35:59,680 --> 00:36:01,760
80 of those bars that you can hit but

780
00:36:01,760 --> 00:36:04,079
most of them can hit two mags at the

781
00:36:04,079 --> 00:36:05,440
same time

782
00:36:05,440 --> 00:36:07,680
getting three batons on each hand is not

783
00:36:07,680 --> 00:36:09,040
feasible

784
00:36:09,040 --> 00:36:10,480
so the

785
00:36:10,480 --> 00:36:12,560
conductor who was going to write a new

786
00:36:12,560 --> 00:36:14,880
piece for this was already anticipating

787
00:36:14,880 --> 00:36:16,560
to use only

788
00:36:16,560 --> 00:36:18,560
single notes at the same time

789
00:36:18,560 --> 00:36:19,839
on the other hand

790
00:36:19,839 --> 00:36:21,599
the system is capable of doing multiple

791
00:36:21,599 --> 00:36:23,280
notes at the same time

792
00:36:23,280 --> 00:36:24,960
the electronics can handle it the midi

793
00:36:24,960 --> 00:36:26,880
can handle it

794
00:36:26,880 --> 00:36:28,880
and then indeed it would be a nice show

795
00:36:28,880 --> 00:36:31,520
element to

796
00:36:31,520 --> 00:36:35,599
try to do this thanks for the idea

797
00:36:35,839 --> 00:36:37,920
and i have a second question

798
00:36:37,920 --> 00:36:40,079
may

799
00:36:40,079 --> 00:36:42,160
you can't make a glissando but i suppose

800
00:36:42,160 --> 00:36:44,160
because of a percussionist application

801
00:36:44,160 --> 00:36:46,079
you're not interested i'm very

802
00:36:46,079 --> 00:36:48,480
interested okay so that's what i hoped

803
00:36:48,480 --> 00:36:51,119
and i watched uh jar

804
00:36:51,119 --> 00:36:52,560
performing quite a few things and what

805
00:36:52,560 --> 00:36:55,920
you see him do in videos is do this

806
00:36:55,920 --> 00:36:58,079
which makes absolutely no distinction in

807
00:36:58,079 --> 00:36:59,280
the sound

808
00:36:59,280 --> 00:37:00,640
but when i was first toying with

809
00:37:00,640 --> 00:37:02,720
photodiode i did see a difference in

810
00:37:02,720 --> 00:37:05,119
intensity between here and here

811
00:37:05,119 --> 00:37:06,960
so i thought yes i can use that to

812
00:37:06,960 --> 00:37:08,480
either change the

813
00:37:08,480 --> 00:37:11,040
frequency of the node or to change

814
00:37:11,040 --> 00:37:13,839
for example the to modulate the volume

815
00:37:13,839 --> 00:37:15,839
so i was

816
00:37:15,839 --> 00:37:19,200
am still dreaming of all kinds of tricks

817
00:37:19,200 --> 00:37:21,200
to improve my instrument beyond just

818
00:37:21,200 --> 00:37:23,200
playing note on or off

819
00:37:23,200 --> 00:37:25,119
but i first want to make it work please

820
00:37:25,119 --> 00:37:26,640
of course i was wondering if you can

821
00:37:26,640 --> 00:37:29,119
make just one screen and slide your hand

822
00:37:29,119 --> 00:37:31,520
through it

823
00:37:31,520 --> 00:37:33,119
that would be another technical

824
00:37:33,119 --> 00:37:37,200
challenge thanks very much nice project

825
00:37:37,200 --> 00:37:38,960
kind of like a theremin that wasn't my

826
00:37:38,960 --> 00:37:41,680
question um with regards to the problem

827
00:37:41,680 --> 00:37:43,760
of the time it takes for each laser to

828
00:37:43,760 --> 00:37:46,160
power up have you considered not fully

829
00:37:46,160 --> 00:37:48,640
powering them down but just dimming them

830
00:37:48,640 --> 00:37:50,160
then they would only need to power up

831
00:37:50,160 --> 00:37:51,839
once

832
00:37:51,839 --> 00:37:54,000
yes

833
00:37:54,000 --> 00:37:55,680
that's actually called the knee voltage

834
00:37:55,680 --> 00:37:58,400
if i recall correctly

835
00:37:58,400 --> 00:38:01,119
is on my to-do list

836
00:38:01,119 --> 00:38:01,839
okay

837
00:38:01,839 --> 00:38:03,200
yes that could solve the problem

838
00:38:03,200 --> 00:38:05,440
altogether except that providing two

839
00:38:05,440 --> 00:38:06,880
different voltages means double the

840
00:38:06,880 --> 00:38:10,160
amount of transistors a solvable problem

841
00:38:10,160 --> 00:38:11,760
okay thanks

842
00:38:11,760 --> 00:38:14,000
if somebody has transistors lying around

843
00:38:14,000 --> 00:38:16,480
that is

844
00:38:17,440 --> 00:38:19,040
please

845
00:38:19,040 --> 00:38:22,400
okay yes hello uh question why

846
00:38:22,400 --> 00:38:24,720
are you buying laser pointers as opposed

847
00:38:24,720 --> 00:38:27,440
to the laser diodes themselves have you

848
00:38:27,440 --> 00:38:28,720
tried

849
00:38:28,720 --> 00:38:31,440
yes i've bought several laser knights

850
00:38:31,440 --> 00:38:33,839
from alex perez china

851
00:38:33,839 --> 00:38:34,960
because

852
00:38:34,960 --> 00:38:37,440
i tried and i couldn't get my hands on

853
00:38:37,440 --> 00:38:38,400
them

854
00:38:38,400 --> 00:38:41,040
and at that point we decided okay

855
00:38:41,040 --> 00:38:43,440
let's give up and just buy laser

856
00:38:43,440 --> 00:38:45,440
pointers instead

857
00:38:45,440 --> 00:38:47,040
because the ones that we could find were

858
00:38:47,040 --> 00:38:48,720
not in our price range

859
00:38:48,720 --> 00:38:49,920
so that's

860
00:38:49,920 --> 00:38:51,440
yeah

861
00:38:51,440 --> 00:38:52,800
the second version do you know if

862
00:38:52,800 --> 00:38:55,359
there's any driver for a laser diode in

863
00:38:55,359 --> 00:38:57,280
the pointers because i suspect they just

864
00:38:57,280 --> 00:38:59,200
rely on internal resistance of the

865
00:38:59,200 --> 00:39:01,359
batteries used so you may want the

866
00:39:01,359 --> 00:39:03,599
constant current driver then you can

867
00:39:03,599 --> 00:39:07,520
adjust the brightness per laser as well

868
00:39:11,599 --> 00:39:13,599
i did not go as far with my experiments

869
00:39:13,599 --> 00:39:16,480
as see if it indeed is one or the other

870
00:39:16,480 --> 00:39:19,520
i did not check whether as power source

871
00:39:19,520 --> 00:39:20,800
no of

872
00:39:20,800 --> 00:39:23,200
current source instead of a voltage

873
00:39:23,200 --> 00:39:24,960
source would make the difference all

874
00:39:24,960 --> 00:39:27,760
diodes are current driven not voltage

875
00:39:27,760 --> 00:39:30,160
have a constant voltage yes

876
00:39:30,160 --> 00:39:32,160
i did not go into

877
00:39:32,160 --> 00:39:34,480
didn't that kind of experiment

878
00:39:34,480 --> 00:39:37,920
that would be a nice trick yes

879
00:39:38,000 --> 00:39:40,079
i i had a question okay john michael

880
00:39:40,079 --> 00:39:42,400
jars glasses if he if he has a very high

881
00:39:42,400 --> 00:39:44,240
powered laser if he did get that in his

882
00:39:44,240 --> 00:39:47,839
eyes would the glasses help at all or

883
00:39:48,720 --> 00:39:51,040
you can make filters that

884
00:39:51,040 --> 00:39:54,160
effectively block out a very tiny bit of

885
00:39:54,160 --> 00:39:56,480
spectrum but then he couldn't see the

886
00:39:56,480 --> 00:39:57,599
laser

887
00:39:57,599 --> 00:40:00,320
does he need to

888
00:40:01,760 --> 00:40:04,319
actually i have seen somebody who has a

889
00:40:04,319 --> 00:40:06,000
laser harp with both

890
00:40:06,000 --> 00:40:07,920
green and red

891
00:40:07,920 --> 00:40:10,400
lasers so

892
00:40:10,400 --> 00:40:12,560
apparently they don't need glasses at

893
00:40:12,560 --> 00:40:13,599
all because

894
00:40:13,599 --> 00:40:15,200
two different frequency makes glasses

895
00:40:15,200 --> 00:40:16,800
too hard

896
00:40:16,800 --> 00:40:17,839
okay

897
00:40:17,839 --> 00:40:19,839
actually i have a general observation as

898
00:40:19,839 --> 00:40:21,839
well um somebody was saying about oh

899
00:40:21,839 --> 00:40:22,839
sorry come

900
00:40:22,839 --> 00:40:24,400
here

901
00:40:24,400 --> 00:40:26,800
i'll get less feedback that way um yeah

902
00:40:26,800 --> 00:40:29,200
one general observation i've got as well

903
00:40:29,200 --> 00:40:30,720
someone's talking about buying lasers

904
00:40:30,720 --> 00:40:32,079
from different places i bought some

905
00:40:32,079 --> 00:40:35,040
lasers off alibaba and i was off ebay

906
00:40:35,040 --> 00:40:36,079
and

907
00:40:36,079 --> 00:40:38,400
i was building a laser maze for my one

908
00:40:38,400 --> 00:40:40,720
of my kids parties which was great but

909
00:40:40,720 --> 00:40:42,960
um when i first bought lasers uh small

910
00:40:42,960 --> 00:40:44,400
ones i wanted them to be bright so they

911
00:40:44,400 --> 00:40:46,000
could be seen i accidentally bought

912
00:40:46,000 --> 00:40:50,560
cutting lasers and um for a child's uh

913
00:40:50,560 --> 00:40:51,760
child's party you have to be very

914
00:40:51,760 --> 00:40:53,599
careful of that so i did spot that in

915
00:40:53,599 --> 00:40:55,839
time but uh it's very easy mistake to

916
00:40:55,839 --> 00:40:57,839
make

917
00:40:57,839 --> 00:40:58,640
yeah

918
00:40:58,640 --> 00:41:01,200
how many kids did you cut uh

919
00:41:01,200 --> 00:41:03,440
none in the end just uh just uh cinched

920
00:41:03,440 --> 00:41:05,920
my hand once oh you see only you seen

921
00:41:05,920 --> 00:41:07,839
you change your hand okay

922
00:41:07,839 --> 00:41:10,720
let's uh anyway okay

923
00:41:10,720 --> 00:41:13,760
anyone else any other questions um

924
00:41:13,760 --> 00:41:14,880
oh cool

925
00:41:14,880 --> 00:41:16,640
well it's pity we can't have a

926
00:41:16,640 --> 00:41:18,480
demonstration of it running live

927
00:41:18,480 --> 00:41:21,119
maybe could you later when it's dark um

928
00:41:21,119 --> 00:41:22,400
or something if there's time somewhere

929
00:41:22,400 --> 00:41:25,040
but um or do you have a village or i i'm

930
00:41:25,040 --> 00:41:26,640
not in the village i'm leaving today

931
00:41:26,640 --> 00:41:28,079
again

932
00:41:28,079 --> 00:41:30,079
actually i promise to be home before

933
00:41:30,079 --> 00:41:32,400
dark

934
00:41:33,040 --> 00:41:36,079
is that promise not to do a demo

935
00:41:36,079 --> 00:41:39,040
and and the the total cost of your kit

936
00:41:39,040 --> 00:41:40,800
what do you if somebody

937
00:41:40,800 --> 00:41:42,960
once you've also once you've finished it

938
00:41:42,960 --> 00:41:44,880
will you publish the will you make it

939
00:41:44,880 --> 00:41:46,960
open source the plans and stuff

940
00:41:46,960 --> 00:41:49,040
the plan is to open source everything

941
00:41:49,040 --> 00:41:52,800
and the kit as it is now is about 160

942
00:41:52,800 --> 00:41:54,319
euro

943
00:41:54,319 --> 00:41:56,160
so that's a good reduction compared to

944
00:41:56,160 --> 00:41:57,599
jeans

945
00:41:57,599 --> 00:41:58,880
yes it is

946
00:41:58,880 --> 00:42:01,280
but it doesn't work and that's actually

947
00:42:01,280 --> 00:42:03,119
quite a small difference it is different

948
00:42:03,119 --> 00:42:04,400
yes

949
00:42:04,400 --> 00:42:06,880
cool okay brilliant well thank you very

950
00:42:06,880 --> 00:42:10,440
much indeed klaus

951
00:42:21,359 --> 00:42:23,440
you