Removable back

Nothing surprising here - note the placement of the battery pocket and
how it will map to the sharpie line I drew in the previous photo
Speaker placement

An additional sharpie line to keep the speaker clear from obstruction
by the components I am about to add
Plastic Thingies

Small rubber feet I purchased at a hardware store. They come 4 to a
sheet, the back is adhesive. I will use these as anchors to drive
screws into.
breadboard in place

The breadboard will fit above the motors. It is held in place with four
screws going through the screw holes and into the rubber feet. You can
see the two additional rubber feet in the right of the photo - these
will be used to anchor the raspberry pi
raspberry pi mounted

this shows the raspberry pi in place. Two screws go through the PCB
holes and into the rubber feet.
Power lines to breadboard

I’ve attached the stock power connector to the breadboard. Later, I
will remove this in favor of a different power supply.
Breadboard with motor leads

All of the leads from the motors, pushbutton and optical sensor are
placed into the breadboard.
sensors & motors to breadboard

another view of the sensor and motor leads connected to the breadboard
First patch
another view of the patch line
Testing connections

This movie shows the result of patching each of the three motors into
the power supply. You can’t see my hands, but I am moving the patch
line into position on the breadboard
TIP31 circuits

The raspberry pi doesn’t supply enough power to directly drive the
motors, so I am using TIP31 power transistors to control the voltage.
Later on, these resistors will be replaced with diodes. DO NOT try to
use the GPIO to drive a motor directly - it will pull more current than
the RPi can supply and you’ll smoke the board.
More TIP31

From left to right, the TIP31 leads are Base, Collector & Emitter. The
base connects to the RPi GPIO pin, the collector connects to plus
voltage, the emitter connects to ground. I tested this circuit by hand
before connecting the raspberry pi
audio circuit

I added a small amplifier using a LM386. You can see it on the far left
of the breadboard, next to the speaker.