to make sure that all of the holes line up and that all
the parts have proper clearance.
I captured the 29 x 32 pattern of the board using a
vector graphics editor. I keep a small library of the images
for the parts used in the circuit and replicated the
placement using the editor. I use this graphic to plan the
interconnections between parts to reduce possible errors.
The placement of the components for the top and bottom
side of the board along with all the connections is shown
in Figure 6. These views can be really helpful when it
comes time to solder connections to the board.
I reflected the placement of the parts to help prevent
the typical PIN1 orientation error for the two chips used
in the circuit. The post shown connected to the battery in
the bottom side component view is a two-pin male
header. This is something I used as an easy test point and
is not required for the circuit to operate. When there are
many closely spaced routes on the board, sometimes I
find it easier to trace an outline of the route using an ultra
fine felt tip pen as a guide. It then just becomes a matter
of point-to-point wiring.
There is only one jumper used on the board. It fits
October 2013 39
■ FIGURE 4. Modification of the plated through
■ FIGURE 5. Trial assembly of the board using standoffs.
■ FIGURE 6. Parts placement and interconnect scheme for the circuit board.
BOTTOM SIDE COMPONENTS INTERCONNECT SCHEME TOP SIDE COMPONENTS