VEHICLE DIY
E
D
F
create 2 small stack plates that sandwich the
servo and remote together on top of the base
plate, such that the rotating servo arm can
push the remote’s button. Position the stack
on one side of the base, to leave enough room
for the Arduino.
I drilled two 2½"×¾" plates and joined
them to the base plate using four 3"-long
#6-32 screws. To tighten the plates down for
holding the servo and remote, I used multiple
washers and nuts on each screw (Figure E).
Relay version: Open your remote and
examine the PCB inside for the button contacts you want to tap into. There are normally
2 types: intertwined traces that connect
electrically when a conductive pad is pressed
against them, and mini pushbuttons soldered
onto the board. For each button, cut and strip
2 wire leads and solder them to the button’s
on-board contacts (Figure F). For trace contacts, you may need to gently clean or polish
them to get a good solder connection.
Follow the schematic (Figure G) to build the
relay circuit on a piece of perf board (Figure
H). The Arduino’s digital outputs don’t deliver
enough power to energize the relay coils
directly, so they drive them via transistor.
Optional – For 2 button control
5V
Button A1
Button A2
Control 1
Button B1
Button B2
Control 2
1.2K;
1.2K;
G
E
4. Mount.
Mark 2 mounting holes for the Arduino on the
base plate, drill with a 1" drill bit, and mount
the Arduino to the plate over short standoffs
using #4-40 screws, washers, and nuts. Fit
the cell shield over the Arduino and plug the
SIM card into the shield (Figure I).
Drill or laser-cut holes in the project box
for mounting the power jack, pushbutton,
and antenna jack dangling off the cell shield.
Locate these components so they won’t get in
the way of the parts inside the box, and make
sure the antenna jack can reach its mounting
hole. I also cut a rectangular access hole in
front of the Arduino’s USB port, for plugging
in the programming cable.
Mount the base plate in the box, and velcro
the 2 power boards from Step 1 against the
inside back of the box. Solder wires to the
power jack and pushbutton, and install them I
H
138 Make: makezine.com/30
