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UNIT 3 ASSEMBLY OF SUBSYSTEM THREE: THE CONTROL BOX UNIT 3
ASSEMBLY OF SUBSYSTEM THREE:
THE CONTROL BOX




FOR THIS TASK YOU WILL NEED:
TOOLS MATERIALS
Soldering iron
Drill
1/4 drill bit
Nut driver
Wire cutter
Wire stripper
Small Phillips Screwdriver
Control box
2 push-button switches
2 toggle switches
2 alligator clips with sleeves (one red one black)
Fuse cap wire
Fuse (10 A slow blow fuse)
Speaker wire
1 loose red wire (#24 stranded hookup wire)
1 loose black wire (#24 Stranded hookup wire)
Time: Unit 3 requires approximately 6 hours to complete:
1 class period to gather parts and prepare the control box (ergonomic design)
1 class period to make the power cable
1 class period to wire button switches
1 class period to wire the toggle (pole) switches
1 class period to finish the control box
1 class period to test Sea Perch in a dry run in the classroom
WARNING:
SOLDERING IRONS GET
VERY HOT
AND CAN CAUSE SERIOUS BURNS.
HOT SOLDER MAY SPATTER. WEAR EYE PROTECTION!!!
TAKE CARE TO NOT SHORT BATTERIES OR SHOCK YOURSELF!
Sea Perch Construction Manual

January 2007
3 - 1 Sea Perch Circuit Diagram

In this section, you will build the control box for your Sea Perch ROV. Below is a circuit
diagram which shows all the electrical connections that will be made. This diagram is a
technical representation, to show the connections, but is not drawn to scale, and leaves
out everything but the wires and electrical components. You can always refer back to
this diagram to understand how and why the wiring should work. The individual steps
have their own circuit diagrams, which are simply parts of this complete diagram. They
also have wiring diagrams, which will help you understand what the wiring actually looks
like.




Figure 26: Sea Perch ROV Circuit Diagram

Sea Perch Construction Manual

January 2007
3 - 2 STEP 1

PURPOSE: Gather the parts for the control box assembly.

MATERIALS:
Control box
2 push-button switches
2 toggle switches (pole switches)
2 alligator clips
1 red alligator clip sleeve
1 black alligator clip sleeve
Fuse cap wire
Fuse (10 A slow blow fuse)
Speaker wire
1 loose red wire
1 loose black wire

Figure 27: Completed control box assembly.

PROCEDURE:
1.

Find the test wires that you used to test your motors in the previous unit.
2.

Remove the alligator clips from the test wires. The alligator clips will be used on
the power cable, and the wires will be used for the control box circuitry.
3.

Gather the other parts required for the control box assembly, as shown below:




Figure 28: Parts for the control box assembly.
Sea Perch Construction Manual

January 2007
3 - 3 STEP 2

PURPOSE: Prepare the control box

MATERIALS:
Control box

TOOLS:
Marker
Drill
1/4 drill bit


Figure 29: Control Box

PROCEDURE:
1.

Using the marker, mark the locations of the holes on your control box, as
shown (approximately) in Figure 30 below. There should be one in the center
of the back for the power to come in, one in the center of the front for the
tether cable to go out, two on the right hand side of the front for the vertical
thruster controls, and two on top for the horizontal thruster controls. Make
sure that the holes for the vertical thrusters leave enough room for the
switches against the sides of the box. Ask your teacher if you are unsure.
2.

Secure the control box in a vise and drill holes with the 1/4 drill bit in the
marked locations.


Figure 30: Control Box hole locations
Figure 31: Cables in holes (see steps 3 & 4)
Sea Perch Construction Manual

January 2007
3 - 4 STEP 3

PURPOSE: Assemble the power cable

MATERIALS:
Speaker wire (5-10 long)
2 alligator clips with sleeves
Fuse cap wire
Solder
Electrical tape
Loose red wire
Loose black wire

TOOLS:
Soldering iron
Wire cutter
Wire strippers
Small scissors

Figure 32: Completed power cable



Figure 33: Power Cable wiring diagram.
In this step you will build the power cable for your
control box. A wiring diagram of the finished power
cable is show in Figure 33.




PROCEDURE:

1.

Cut about 3 (7.5cm) of wire off of the end of
the red and black loose wires. Set these short
pieces aside for a later use with the toggle
switches.
2.

Cut the remaining red and black wires into four
equal length pieces each (4 black and 4 red). If
your pieces will be less than 5 (12.5cm), then
ask your teacher for extra wire.
3.

Strip about 1/4" (6mm) of insulation from each
end of each piece. Twist the inner wires
(strands) on each end to prevent fraying and
breaking.
Sea Perch Construction Manual

January 2007
3 - 5
4.

Take one end of each of the four red wires and twist them all together, as shown
in Figure 34 below. The figure shows 3 wires, but youll have four.
5.

Do the same with the black wires. These spliced wire bundles will distribute
power in your control box.


Figure 34: Spliced wire bundles

6.

Find the power cable (speaker wire), and determine which side of it is positive
and which is negative. Notice that there are two conductors inside, each with its
own insulation, and attached to the other with a thin web of insulation material.
Usually the insulation on one side is ribbed (like corduroy) and the other is
smooth. Other times, one is marked with white or black stripes, or other
indicators. We will call the ribbed or marked side the positive (+) side.
7.

On each end of the speaker wire (power cord), carefully separate the two
conductors for about 1 (2.5cm). This is best done by snipping the thin web of
plastic between the wires with a small pair of scissors, or a fine pair of wire
cutters. Be careful not to nick the insulation on the conductors.
8.

On one end of the power cord, leave the separated section only 1 (2.5cm) long.
On the other end, pull the two wires apart for about 14 (35cm).
9.

On the part of the cord that you just separated, find the positive (ribbed or
marked) side and cut off 13 (33cm) of the positive wire. This section will be
replaced with the fuse cap wire, as shown in Figure 35 below.


Figure 35: Battery end of the power cable.

Sea Perch Construction Manual

January 2007
3 - 6
10.

Strip 1/2 (1.3cm) of insulation off both ends of the fuse cap wire. The fuse cap
wire does not have a positive and negative side it will work either way.
11.

Strip 1/2 (1.3cm) of insulation off of all four ends of the power cord (speaker
wire), and off both ends of the fuse cap wire. Twist the conductor strands on each
end together to prevent fraying and breaking.
12.

Attach the fuse cap wire to the positive (ribbed/marked) side of the speaker cable,
(where you cut off the 13/33cm piece). Twist the wires together, solder the
connection, and cover it with electrical tape.
13.

Slide the red alligator clip sleeve onto the loose end of the fuse cap wire, and the
black alligator clip sleeve onto the negative side of the power cord.
14.

Attach alligator clips to the fuse cap wire (+), and to the negative side of the
power cord (-). Stick the wire in through the back of the clip, and up through the
hole near the screw. Loosen the screw and wrap the wire around it clockwise.
Tighten the screw. You can solder the connection if you want to. At this point,
your power cable should look like Figure 35.
15.

Push the sleeves down over the alligator clips and put the fuse into the fuse cap.
16.

Pass the loose end of the power cable (no alligator clips) through the hole in the
back of your control box. Tie a strain-relief knot about 6 (15cm) up the cord,
inside the control box.
17.

Take the spliced bundle of 4 red (+) wires, and twist the bundled end onto the
positive (ribbed/marked) side of the speaker wire. Take the spliced bundle of 4
black (-) wires and twist the bundled end onto the negative (smooth) side of the
speaker wire. Solder the connections and cover them with electrical tape, as
shown in Figure 36.