Make Electronics

Getting Somewhat More Serious 137

Experiment 15: Intrusion Alarm Revisited

essentIAls

Perfboard soldering procedure

Carefully note the position of a component on your bread-
board, and then move it to the same relative position on the
perfboard, poking its wires through the little holes.

Turn the perfboard upside down, make sure that it’s stable,
and examine the hole where the wire is poking through, as
shown in Figure 3-96. A copper trace surrounds this hole
and links it with others. Your task is to melt solder so that
it sticks to the copper and also to the wire, forming a solid,
reliable connection between the two of them.

Take your pencil-style soldering iron in one hand and some
solder in your other hand. Hold the tip of the iron against
the wire and the copper, and feed some thin solder to their
intersection. After two to four seconds, the solder should
start flowing.

Figure 3-96 Figure 3-97

Figure 3-98. To establish a connection between a section of wire
and a copper trace on perforated board, the wire is pushed
through the hole, and solder (shown in pure white for illustra-
tive purposes) completes the connection. The wire can then be
snipped short.

Allow enough solder to form a rounded bump sealing the

wire and the copper, as shown in Figure 3-97. Wait for the

solder to harden thoroughly, and then grab the wire with

pointed-nosed pliers and wiggle it to make sure you have

a strong connection. If all is well, snip the protruding wire

with your cutters. See Figure 3-98.

Because solder joints are difficult to photograph, I’m using

drawings to show the wire before and after making a rea-

sonably good joint, which is shown in pure white, outlined

with a black line.

Actual soldered perfboard is shown in the photographs in

Figures 3-99 and 3-100.

Figure 3-99. This photograph was taken during the process

of transferring components from breadboard to perforated

board. Two or three components at a time are inserted from

the other side of the board, and their leads are bent over to

prevent them from falling out.

Figure 3-100. After soldering, the leads are snipped short and

the joints are inspected under a magnifying glass. Another two

or three components can now be inserted, and the process can

be repeated.