■ FIGURE 3. Excess wire wrapped
around the servo and hot-glued
■ FIGURE 4. BASIC Stamp 1 OEM
module and servo mounted to PCB.
■ FIGURE 5. Checking the servo motor has
clearance to turn above the BS1 OEM board.
skipped breadboarding the circuit
and just started soldering the BASIC
Stamp 1 onto the perf board. The
.100” pin spacing lined right up and
it was nice and solid once soldered.
I then took the servo motor and
wrapped the excess lead length
around the body (Figure 3) creating a
■ FIGURE 6. Screw terminals for
power and headers for
■ FIGURE 7. Solder-side view of the
PCB with all wiring complete.
nice “candy stripe” look. I then hot-melt
glued the servo to the perf board
(Figure 4) after checking to be sure
that with a servo horn attached, it would
clear the top of the BASIC Stamp board
(Figure 5). I flipped the board over
and added a three-pin .100” header
for the servo, a 90 degree, right-angle
two-pin header for the pushbutton
and the pushbutton’s LED, and a pair
of screw terminals for power input
(Figure 6). To make the board easier
to mount in the jar, I added some
metal standoffs to its four corners.
The grid-style PCB (printed circuit
board) worked well for this design as
I could use the strips that go down
the center as a power bus; the pads
at the edges let me bring out the pins
from the Stamp 1 to the edge (Figure
7). As the BASIC Stamp OEM board
has a full LM2940 regulator on it, I
decided to use it to regulate power
for the entire project. This way, the
Detector could be powered by a
six volt battery pack or by a higher
■ FIGURE 8. Lighted pushbutton mounted in jar lid.
voltage external power supply.
If you decide to build the unit
using a standard BASIC Stamp 1, I
suggest you add an LM2940 voltage
regulator to provide the V+ as this way
you won’t have to worry about
destroying components if the wrong
voltage level is accidentally applied.
Also, if you look closely at the solder
side (Figure 7) you will notice I included
a diode in series with the power
input as insurance against improper
polarity. I took these extra steps since
I knew the unit would be used around
children and there was a good
chance the wrong wall wart might be
used to power the unit by accident.
MOUNT ‘EM UP!
Now that I had the PCB mostly
settled, I wanted to get started on the
top of the enclosure. It was fairly easy
to use a Dremel to cut a hole for the
pushbutton switch (Figure 8), but the
next step would require some pretty
■ FIGURE 9. Old PCB hot-melt glued
to lid top as a drill template.