Prototypes are designed as a schematic in EDA (KiCAD) then brought to life on a Breadboard or Perfboard. Once its working as desired, the next step is to draw the PCB in EDA. KiCAD files upload directly to oshPark, a great Made in the USA PCB manufacturing service for prototype to production scale. Order the components next at Digikey or similar, and populate the PCB when it arrives a couple weeks later.
Goats love mangos
Humans love thermostats
For one off's you can stop right at the perfboard. In proper Jungle Robotics form, this car needed a thermostat for the engine coolant, and AC refrigerant. Some carefully wired thermistors, relay's, and a programmed Arduino later, it's all thermostatically controlled.
How high can you stack PCB's? When you're sticking with the form factor of a Raspberry Pi, as high as is necessary. As pictured from the bottom up: 24v power management PCB, 5v power management PCB, Raspberry Pi 4.0, Communications Teensy PCB, and finally Step Generation PCB with a Teensy on top.
These pictures offers a nice view right into the traces 'printed' on the circuit board. The traces are decent sized, 0.3mm wide. The 'fab house' will etch them half the width if desired, but why push it.
The Raspberry Pi talks to the Communications Teensy via a serial bus, which then communicates with the Step Generation Teensy via a second serial bus, all going through headers connecting the boards to keep lines as straight and noise free as possible. These buses run at about a megahertz (a million times a second) so keeping everything tidy is critical.
OpAmps (operational amplifiers) take the step data generated by the top Teensy 3.2 and send it out to stepper drivers which spin the robot's arm motors. The communications Teensy monitors each limit switch and motor encoder to make sure everything is operating correctly, taking correcting steps if necessary.
Previous motion control pcb's had used NPN transistors to output step data to the stepper drivers. OpAmps proved a much more buffered solution, separating the Teensy from the output signals better than the NPN transistors. In this situation, you're looking for a rail-to-rail dual supply opAmp
Shaggy tending to his 'goots'
Team work makes the dream work. This Jamaican goot dog does a great job keeping an eye on the hoard. I'm not sure this is what the people who installed the picnic area were thinking, but it is nice to see it being enjoyed.