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ELEX K2 (Hohner Stringvox) (r3) K2-1 Voicing Board: Schematic
D1
C1
10 –10+20%
25V
R3
22K
Q1
R1 4K7
R2
1K0
D2
1
sustain
[†]
PHB
pedal
contact
Component codes given here are assigned arbitrarily in the
absence of original documents.
Transistors are FBC 237B. Diodes are BA130. Resistors are
±5%. All nonpolarised capacitors are rated 50V or above.
PHB: Piano Harpsichord Bass
C2
4 7 –10+20%
50V
R4
R5
D3
180K
1K0
Q2
D5
R6
R7
R8
R9
15K
560K
820K
47K
D4
7
+1 5
–1
GND
PHB
audio
† Pin 3 function is uncertain; it is connected to ground through
a power resistor. Speculatively, it may limit negative voltage
from the contacts and voltage spikes resulting from their
movements?
Positive and negative voltage inputs here are as measured.
R20 47K
C7
2 2 ±20% 50V
C5
*
C6
*
Q3
C3
R10 47K
C4
*
8
GND
There are twenty versions of the board each with varying
resistor (R12, R18) and capacitor (C3, C4, C5, C6, C9)
values. The consistent values are given on the diagram.
* Different versions use either C6, C4 & C5, or C5 & C6, but
not all three.
designed c.1975 ELEX S.p.A. (Excelsior) | drawn 2024 electropict
D8
D9
R13
R17
47K
15K
D6
D7
D10
D11
R11
R14
R15
R16
R12
4K7
22K
3K3
22K
Strings
Strings
strings
Cello
Cello
audio
decay
contact
decay
audio
C8
2 2 ±20%
50V
C9
C10
Q4
1n0
R19
R18
560K
16
GND
TONE
TONE
2
1
TONE 1 and 2 are the lower
and upper octave divider
outputs for each note.
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