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ELEX K2 (Hohner Stringvox) (r3) M174 Modulation Oscillator Board: Schematic
VR1 5K0
VR1 5K0
R2 180K
R2 180K
R3 180K
R3 180K
R1 10K
R1 10K
R12
R12
47K
47K
R11
R11
1K0
1K0
+13
Component numbering is added arbitrarily in the absence of original documentation, except ICs which are as on the board.
All ICs are UA4558TC. All diodes are BZX85C5. All resistors are ±5%, and
D1
D2
C2
150n
R4 180K
R4 180K
8
5
IC1
1
4
R5 120K
R5 120K
C1
150n
C3
150n
R17
R17
47K
47K
R16 1K0
R16 1K0
8
R14 47K
R14 47K
IC3
1
R19 1K0
R19 1K0
R18
R18
R13 100K
R13 100K
10K
10K
C8
330n
R15 100K
R15 100K
–13
VR2 5K0
VR2 5K0
R7 180K
R7 180K
R8 180K
R8 180K
R6 10K
R6 10K
5
4
R20 22K
R20 22K
R24
R24
47K
47K
C9
R21
R21
330n
220R
220R
1
1
⁄
⁄
W
W
2
2
modulation outputs
1
⁄
W except where stated.
4
designed c.1979 ELEX S.p.A. (Excelsior) | drawing 2024 electropict
D4
D3
C5
1 5
R9 180K
R9 180K
8
5
IC2
1
4
R10 120K
R10 120K
C4
1 5
C6
1 5
R28
R28
47K
47K
R23 220R
R23 220R
⁄
⁄
W
W
1
1
2
2
8
R27 47K
R27 47K
IC4
1
R22 220R
R22 220R
1
1
⁄
⁄
W
W
2
2
R29
R29
R26 100K
R26 100K
18K
18K
C10
3 3
R25 100K
R25 100K
C7
100 35V
5
4
R30 18K
R30 18K
C11
3 3
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