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Prepping the eyelet boards
This circuit is built on three eyelet
boards: the large main eyelet board,
the middle-sized filter cap board, and
the small bias board . Gather those
three boards now .
STEP 8
Number the eyelets and holes
In these instructions, we’ll refer to the
eyelets and holes on the main eyelet
board by number . On the bias board
and filter cap board, we’ll use letters .
Orient the boards as shown below
and use a pencil to add the numbers
and letters .
L
S
K
R
Q
J
P
I
O
H
M
G
N
38
28
1
2
3
4
5
6
7
8
51
52
10
34
54
68
58
43
49
50
32
31
61
44
35
36
60
63
62
45
36
11
55
41
12
14
15
56
42
16
19
21
23
26
29
46
64
39
47
48
30
65
66
67
53
9
69
70
71
72
59
57
73
74
40
13
20
22
27
18
17
25
24
83
85
86
87
90
91
92
94
97
96
95
93
98
37
88
89
99
76
77
78
81
82
79
80
33
84
75
A
B
C
D
F
E
Main
Bias
Filter cap
STEP 10
Drill the filter cap boards
Drill 1/4" holes in the two upper cor-
ners of the taped-together filter cap
board and insulator (holes G and M) .
Drill a third 1/4" hole centered be-
tween eyelets P and R (hole Q) .
Separate the boards and set the insu-
lator board aside .
The red dots on these boards indicate
holes you’ll drill in the next steps . The
main board and bias board each get
two small mounting holes that don’t
need to be numbered .
The filter cap board will get three
holes drilled for wires to pass through
(holes G, M, and Q) . Even though
those holes aren’t there yet, mark the
letters as shown while labeling the
rest of the holes .
Insulator
Main eyelet board
Filter cap board
Bias board
Insulator
Insulator
Write these n letters
on the boards:
M
Q
G
STEP 9
Match the insulators
For each of these three boards there
is a matching blank insulator board of
the same size . These insulators will be
mounted behind the eyelet boards to
keep the electrical connections from
touching the metal chassis .
Align the three insulator boards
behind their eyelet boards . Tape the
pairs of boards together, to keep them
aligned for the next step .
