BLS / AlephP1.7 Volume Control Option

[mefinnis]

Hiya All,

For my next project I am looking at making a P1.7

There are a number of options for the relay-style volume control, however while looking in the Farnell catalog for a rotary encoder I found this little animal:

http://www.bourns.com/2/pdfs/ACE.pdf

Now my knowledge of digital control circuitry is minimal (approaching absolute zero), however while looking at this I suspect it could almost directly drive the switching bipolars for the relays ??

Comments from those who actually know what they are talking about .... PLEASE

Regards

Mark

[jleaman]

ive got a aleph p1.7 almost finnished need connectors transformers and caps. for psu and few small things. but i would like to build a digital volume and a digital input selector with lcd. and must be balanced too.: O )

[Dane]

I not sure if it's safe to answer...

This encoder returns gray code not normal binary, plus you would have switch bounce. The application note shows it being used with a microprocessor that has a translation table, and it's still only 128 positions. Plus being 360 degress, if you are not carefully when turning it down... it will wind up at full volume again!

A simple potentiometer to ADC/DAC to Relay drivers is the easier route without a micro, a 10 bit and discard least significant bits.

Of course the advantage of the CPU is that you can approximate the audio taper curve instead of being linear.

Here is the same table sorted by the Binary number...
A few are missing... half of them.

Position p8 p7 p6 p5 p4 p3 p2 p1 Decimal
56 0 0 0 0 0 0 0 1 1
40 0 0 0 0 0 0 1 0 2
55 0 0 0 0 0 0 1 1 3
24 0 0 0 0 0 1 0 0 4
39 0 0 0 0 0 1 1 0 6
52 0 0 0 0 0 1 1 1 7
8 0 0 0 0 1 0 0 0 8
57 0 0 0 0 1 0 0 1 9
23 0 0 0 0 1 1 0 0 12
36 0 0 0 0 1 1 1 0 14
13 0 0 0 0 1 1 1 1 15
120 0 0 0 1 0 0 0 0 16
41 0 0 0 1 0 0 1 0 18
54 0 0 0 1 0 0 1 1 19
53 0 0 0 1 0 1 1 1 23
7 0 0 0 1 1 0 0 0 24
20 0 0 0 1 1 1 0 0 28
19 0 0 0 1 1 1 0 1 29
125 0 0 0 1 1 1 1 0 30
18 0 0 0 1 1 1 1 1 31
104 0 0 1 0 0 0 0 0 32
105 0 0 1 0 0 0 0 1 33
25 0 0 1 0 0 1 0 0 36
106 0 0 1 0 0 1 0 1 37
38 0 0 1 0 0 1 1 0 38
58 0 0 1 0 1 0 0 1 41
37 0 0 1 0 1 1 1 0 46
14 0 0 1 0 1 1 1 1 47
119 0 0 1 1 0 0 0 0 48
118 0 0 1 1 0 0 0 1 49
107 0 0 1 1 0 1 0 1 53
4 0 0 1 1 1 0 0 0 56
3 0 0 1 1 1 0 1 0 58
109 0 0 1 1 1 1 0 0 60
108 0 0 1 1 1 1 0 1 61
2 0 0 1 1 1 1 1 0 62
1 0 0 1 1 1 1 1 1 63
88 0 1 0 0 0 0 0 0 64
89 0 1 0 0 0 0 1 0 66
51 0 1 0 0 0 1 1 1 71
9 0 1 0 0 1 0 0 0 72
10 0 1 0 0 1 0 0 1 73
90 0 1 0 0 1 0 1 0 74
22 0 1 0 0 1 1 0 0 76
11 0 1 0 0 1 1 0 1 77
12 0 1 0 0 1 1 1 1 79
42 0 1 0 1 0 0 1 0 82
43 0 1 0 1 0 0 1 1 83
21 0 1 0 1 1 1 0 0 92
126 0 1 0 1 1 1 1 0 94
127 0 1 0 1 1 1 1 1 95
103 0 1 1 0 0 0 0 0 96
102 0 1 1 0 0 0 1 0 98
91 0 1 1 0 1 0 1 0 106
116 0 1 1 1 0 0 0 0 112
117 0 1 1 1 0 0 0 1 113
115 0 1 1 1 0 1 0 0 116
93 0 1 1 1 1 0 0 0 120
94 0 1 1 1 1 0 0 1 121
92 0 1 1 1 1 0 1 0 122
114 0 1 1 1 1 1 0 0 124
95 0 1 1 1 1 1 0 1 125
113 0 1 1 1 1 1 1 0 126
0 0 1 1 1 1 1 1 1 127
72 1 0 0 0 0 0 0 0 128
71 1 0 0 0 0 0 0 1 129
68 1 0 0 0 0 0 1 1 131
73 1 0 0 0 0 1 0 0 132
29 1 0 0 0 0 1 1 1 135
70 1 0 0 0 1 0 0 1 137
69 1 0 0 0 1 0 1 1 139
35 1 0 0 0 1 1 1 0 142
34 1 0 0 0 1 1 1 1 143
121 1 0 0 1 0 0 0 0 144
122 1 0 0 1 0 0 1 0 146
74 1 0 0 1 0 1 0 0 148
30 1 0 0 1 0 1 1 1 151
6 1 0 0 1 1 0 0 0 152
123 1 0 0 1 1 0 1 0 154
124 1 0 0 1 1 1 1 0 158
17 1 0 0 1 1 1 1 1 159
67 1 0 1 0 0 0 1 1 163
26 1 0 1 0 0 1 0 0 164
27 1 0 1 0 0 1 1 0 166
28 1 0 1 0 0 1 1 1 167
59 1 0 1 0 1 0 0 1 169
15 1 0 1 0 1 1 1 1 175
5 1 0 1 1 1 0 0 0 184
110 1 0 1 1 1 1 0 0 188
111 1 0 1 1 1 1 1 0 190
16 1 0 1 1 1 1 1 1 191
87 1 1 0 0 0 0 0 0 192
84 1 1 0 0 0 0 0 1 193
45 1 1 0 0 0 0 1 1 195
86 1 1 0 0 0 1 0 0 196
85 1 1 0 0 0 1 0 1 197
50 1 1 0 0 0 1 1 1 199
46 1 1 0 0 1 0 1 1 203
33 1 1 0 0 1 1 1 1 207
83 1 1 0 1 0 0 0 1 209
44 1 1 0 1 0 0 1 1 211
75 1 1 0 1 0 1 0 0 212
31 1 1 0 1 0 1 1 1 215
32 1 1 0 1 1 1 1 1 223
100 1 1 1 0 0 0 0 0 224
61 1 1 1 0 0 0 0 1 225
101 1 1 1 0 0 0 1 0 226
66 1 1 1 0 0 0 1 1 227
62 1 1 1 0 0 1 0 1 229
49 1 1 1 0 0 1 1 1 231
99 1 1 1 0 1 0 0 0 232
60 1 1 1 0 1 0 0 1 233
47 1 1 1 0 1 0 1 1 235
48 1 1 1 0 1 1 1 1 239
77 1 1 1 1 0 0 0 0 240
82 1 1 1 1 0 0 0 1 241
78 1 1 1 1 0 0 1 0 242
65 1 1 1 1 0 0 1 1 243
76 1 1 1 1 0 1 0 0 244
63 1 1 1 1 0 1 0 1 245
64 1 1 1 1 0 1 1 1 247
98 1 1 1 1 1 0 0 0 248
81 1 1 1 1 1 0 0 1 249
79 1 1 1 1 1 0 1 0 250
80 1 1 1 1 1 0 1 1 251
97 1 1 1 1 1 1 0 0 252
96 1 1 1 1 1 1 0 1 253
112 1 1 1 1 1 1 1 0 254

[promitheus]

well you can´t use that directly. There is no logic in the way the outputs change. You can only use that with a microprocessor to decode the different outputs into binary code.