Hi to the forum. I am taking a first try with an Arduino board by building a motorized telescope focusing unit from a project on SourceForge. This project uses an Arduino Uno with an L293D motor shield. The stepper is a 28BYJ-48 motor rated at 5-7.5v. Setting this up and burning a test program to the Arduino results in a fully functioning motor powered by the 5V USB connection to the laptop. The focuser unit will be operated through a Windows program so the USB port will be connected all the time. Running the motor in this configuration is convenient. However the Arduino board offers an external power jack, and the L293D has facility for a separate power connection. Should I wish to use a 12 volt stepper motor, I would have to provide this voltage through either external power connection.
My question is whether the provision of 12v through either the Arduino or motor shield external power jacks will conflict with the 5v USB power that is now running the motor? The L293D has a jumper that allows power to the motor shield to power the Arduino board. Is this a good idea if the USB port is in use? Is it better to power the Arduino Board with 12V, or the motor shield?
Appreciate some help with these basic question. I look forward to focusing my telescope from the desk instead of standing outside in winter.