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©2017 Stewart-MacDonald
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Step 5: Install two transistors
Q1 and Q2 are 2n3904 JFET* transistors. They are directional, and need to
be installed in a specific orientation. Note that they have a flat side. On the
circuit board, their location outlines also have a flat side. Install the transistors
to match these outlines.
*JFET: Junction Gate Field-Effect Transistor
Step 4: Install the operational amplifier
The operational amplifier consists of two parts: the op-amp itself (U1), and
the socket it plugs into (U1.2).
You’ll solder the socket first, then install the op-amp in the socket.
The op-amp has to be oriented correctly in order to function properly. There
are two indicators on the circuit board to guide you in positioning it:
1. The rectangular U1 position marker has a small notch at one end. Align the
similar notch in socket U1.2 when installing the socket.
2. The U1 position marker has a dot in one corner. There is a dot molded into
the corner of op-amp U1. Align these corners when pressing the op-amp
into place.
Solder socket U1.2 to the board. The op-amp U1 then snaps in without solder.
This feature allows you to try different op-amps with no soldering.
JHS Pedals Kit
For Stew Mac
DC Jack
JHS808
D8
T
S
S
T
R1
R23
R10
R11
R18
R14
D5
D4
D1
OutJ
InJ
P78868
Q1
Q2
C4
C3
C1
C15
C14
C8
C12
C5
C7
C10
C9
C2
R2
R12
R21
R13
R15
R4
R5
R20
R22
R3
R9
R16
R17
R19
R8
R6
R7
D7 D3
D2
U1
C6
C13
.22J63
.22J63
.1J63
.1J63
47nJ
U1 Low noise op-amp (4558P 500nA)
U1.2 socket for op-amp
1J63
1J63
.1J63
JHS Pedals Kit
For Stew Mac
DC Jack
JHS808
D8
T
S
S
T
R1
R23
R10
R11
R18
R14
D5
D4
D1
OutJ
InJ
P78868
Q1
Q2
C4
C3
C1
C15
C14
C8
C12
C5
C7
C10
C9
C2
R2
R12
R21
R13
R15
R4
R5
R20
R22
R3
R9
R16
R17
R19
R8
R6
R7
D7 D3
D2
U1
C6
C13
.22J63
.22J63
.1J63
.1J63
.1J63
47nJ
Q1, Q2
Transistor (2n3904)
1J63
1J63
U1