when a solder kit had
wires soldered directly
to the PCB with no
Invariably, the wires
would soon break off
from metal fatigue.
I discovered a way to
prevent this, and
suspect many other
people have discovered
the same method.
I provide strain
relief to the wires by
drilling larger holes
near the solder pads.
Insulated wires pass
through these larger
holes before their
stripped ends are
soldered to the PCB.
Now, the wires can flex
without straining and
breaking their soldered connection to
There are 20 strain relief holes in
the PCB for this purpose, and they
are drilled to match the outside
diameter of your insulated wire.
The remaining eight holes are
mounting holes. The four holes in the
corners of the PCB are where the
flight computer is mounted to the
base material. Drill these holes large
enough for #4-40 bolts. The last four
holes are for mounting the DB- 9
connectors. Drill these holes for #2-
56 bolts. Refer to Figure 1.
to the PCB
This is the order of assembly that
I recommend for putting the PCB
together (your mileage may vary).
Start with the six jump wires (these
are used to bridge traces beneath the
PCB and are shown as the white lines
in Figure 2), followed by the resistors.
Next, solder IC sockets. Do not
solder the BASIC Stamp or the MAX-
186 directly to the PCB, and do not
insert the ICs into their socket prior
to soldering the socket. Hold off
inserting the BS2pe and MAX186
until after testing is complete.
You’ll probably want to cut the
analog and digital port receptacles
from a longer block of receptacles.
Do this by pulling out the row of pins
you need to cut through and using a
hack saw to do the cutting. Finish the
receptacle by using a utility knife and
file to smooth the roughly cut edge
of the plastic body.
Insert one of the receptacles into
the PCB and only solder two
diagonal corner pins. Then, flip the
PCB over and verify that the
receptacle is still flush on the PCB. If
it’s not, press on the high corner and
reheat that pin until the receptacle
snaps down. Now, you can solder
the receptacle’s remaining pins.
Repeat the process for the second
Unlike the analog and digital
ports, the servo port is a male header
64 July 2014
■ FIGURE 2. Follow this diagram for the
placement of parts in your etched and
drilled printed circuit board.
■ FIGURE 1. The 20 strain relief holes are circled in green, the PCB
mounting holes are circled in red, and the DB- 9 mounting holes are
circled in blue.