all bare leads longer than 1/4”. When wiring is complete,
solder the connections shown filled in with black; leave
the gray connections for soldering later.
Use Wiring Diagram 3 to wire the power supply
components. Trim wires and leads to their minimum
length and use spaghetti wire insulation on all bare leads
longer than 1/4”.
When wiring is complete, solder the connections
shown filled in with black; again, leave the gray
connections for soldering later.
The next step is to build LN-1: the audio amplifier
module. Instructions are included with the kit. A few
changes must be made. Do not install the microphone or
the 3.3K ohm resistor (LN-1 R1).
Also, replace the 1K ohm resistor (LN-1 R2) with a
100K ohm, and the 10K ohm resistor (LN-1 R3) with a
680K ohm. The change is necessary to decrease LN-1’s
loading effect on V1-B’s output.
Add external wires to LN1 as indicated on Wiring
Diagram 4, adhering to the color codes. Make all wire
lengths 6” initially. Note that the input wires connected to
the “MIC” point are tightly twisted for the first 3-1/2”.
Adjust R6 (the LN-1 gain control) to maximum, fully
After LN-1 is built, mount it to the base with 1/4”
standoffs and 4-40 x 1” machine screws. Use Wiring
Diagram 4 to wire audio module LN-1 to V1, the power
supply, and the speaker/earphone circuit.
When wiring is complete, solder all connections.
The final stage of construction involves making and
installing the spiderweb coil. The fiberboard used as
backing for picture framing is an excellent choice from
which to make the coil. You may have to search around to
find just the right material. The perfect selection will be
slightly less than 1/8” thick and similar to (but not as hard
as) the tempered hardboard.
Copy the pattern of Figure 7 and glue it to the
fiberboard. Use a 3-1/2” circular saw to cut out the coil
shape. The finished coil will be nearer the 3-1/4” diameter
May 2015 31
■ FIGURE 7.
■ Wiring Diagram 4.
LN-1 audio module
and speaker wiring.