The finished QuickStart Brain with expansion board
some of the circuits. These aren’t really intended to supply
enough current for all the servos. For those, we use an old
trick and have a couple of large 1N5401 diodes (in series)
to drop the voltage from the battery pack to a safe level for
the servo power supply.
The robot won’t need to be opened up just to update
the code or install a new program because I added a USB
panel mount connector to each of the MiniBots. This goes
with the finished look and feel of the robot. The short USB
panel mount cable just plugs directly into the Arduino
board. For the QuickStart, I also needed a USB to mini USB
adapter to make the connection.
Building the Propeller-Based
One thing to watch out for when mounting the
QuickStart (or any other board) is if the mounting holes are
electrically connected to anything or if they are isolated. If
you are unsure, you may end up causing a short circuit or
ground loops that you never intended. Since I was
mounting the board to the plastic body using a small
aluminum bracket, I wasn’t too concerned about that
because the plastic body would act as an insulator.
What I didn’t expect was that the one mounting hole I
chose near the upper left of the board by the 40-pin
connector on the QuickStart would be troublesome. I had
pulled out some of my recycled fasteners to mount the
board and the screw had a starred lock washer on it.
Normally, that would be fine but that mounting hole
just happened to have a positive ground plane right around
the ground connection of the large pad around the hole.
There was hardly any clearance between the two and the
lockwasher on the screw caused a short right at that spot.
The board had been working flawlessly but didn’t do
anything once it was mounted in the robot.
The finished Propeller QuickStart powered robot.
The finished QuickStart expansion board (from top).
The finished QuickStart expansion board (solder side).
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