Solder the six
resistors and two
capacitors to the
board. If you have
color codes, use
an ohmmeter. The
board is marked.
Solder the voltage
regulator to the
board with its flat
pointing to the
center of the board
and Q1 to its pads
noting its markings.
Solder the socket
for IC1 with lead 1
going to the square
pad. Solder the LED with its long lead to the square pad.
Check out Figure 3.
Solder two #18 black wires to the negative pads and
two #18 red wire to the positive pads as in Figure 4.
Some of you will be asking, “Wouldn’t it be better to
move the pads for the wires closer to the edge?” It
would be more convenient. However, PCB traces don’t
fare well with high amperage. If you calculate out the
width of the trace needed to transfer 12 amps with 1 oz
of copper trace, it would have to be . 5” wide — one-third
of the board width.
Thread Q2’s leads through the board transistor pads.
Speaking from experience, make sure the resistors are
next to the body of Q2 (Figure 5). Mounting the board
in backwards will reverse the leads of Q2 and will cause
failure. Use the two 1/4” nylon spacers and two 5/8”
6-32 screws. Put the screws through the back of the
heatsink and screw them into the board. The board will
self-tap. Solder Q2’s leads.
There are mounting slots on the heatsink for
mounting the unit.
Using the Unit
Using wire nuts, connect the unit to the batteries
first. The LED should turn on. Green shows the batteries
26 March 2014
■ FIGURE 4.
■ FIGURE 3.