following the pattern, they will be
You could easily omit the
three-pin power inlet socket and
just run an AC cord into the box.
The LCD display could also be
eliminated, but it does provide a
nice way to check on the Arduino,
the RTC output, and when the
By cutting down from the top
edge of the bottom section of the
box for the 120 volt duplex wall
jack and the three-pin power inlet
socket, it made it quite easy to
produce the openings; you are only
cutting out three sides of a
Be sure to leave space to
mount the breadboard with its
components, and have reasonable
clearance for the 120 volt wires
that connect power to the relays
and the duplex wall jack.
The most time is spent doing the point-to-point wiring on the breadboard. For this, I like
to have a printout of the schematic. As I add a
connection or wire to the circuit, I use a red
marker on the schematic to record what has
Both the dual relay board and the LCD
display have four-pin headers for connections.
Use short pre-made four-pin jumper cables to
easily connect these to the two four-pin headers
created on the breadboard. The CR2032 battery
is a must for the RTC. Once programmed, this
allows you to disconnect the power and
reconnect it later, with the backup battery
supplying the power to the RTC and
maintaining the time.
The DS3234 integrated circuit only comes
in a surface-mount package (an SOIC- 20). This
means the pins are spaced on .05 inch centers.
A SchmartBoard SMT to DIP adapter is a small
printed circuit board (PCB) with standard 0.1
inch spaced pins that you solder the SOIC- 20 package on.
With some care and forethought, it is actually not too
difficult to solder the DS3234 to the SchmartBoard by
Here is my method. First, using the smallest soldering
tip you have available, place the smallest amount of solder
possible on diagonally opposed corners of the SOIC- 20
pads on the SchmartBoard. Using a toothpick (it is also
insulated against static) to help place the IC perfectly
centered on the pads, press one corner pad down with
the soldering iron tip, melting the small solder dot
underneath. Do not go on until this first pin is soldered
August 2016 33
■ FIGURE 4. Interior of the box showing parts placement.
■ FIGURE 5. Side view of the three-pin power inlet socket.
■ FIGURE 6. Side view of the duplex 120 volt wall jack.