Multiple power supplies

[sjcomp]

Hello,

I plan to control a couple of 12V motors (http://microcontrollershop.com/product_info.php?products_id=3087) and a 5V Motor (in a pump (http://www.amazon.com/gp/product/B004HHW0FU)) with teensy3. What would be the best way to go about having access to these voltages. By default I envision a power cable from 110V outlet connected to two power adapters (one for 5V and one for 12V). I would use output from 5V adapter to supply power to teensy and 5V motor and the other adapter will feed power on A4988 (http://www.pololu.com/catalog/product/1182) Stepper Motor Driver Carrier, which will drive the motor. Is there a better alternative, such as having a single circuit that could provide both voltages? I do not need both voltages active in my circuit at the same time, so maybe I can get a variable power supply that can be controlled by teensy? Any suggestions.

Thanks,
Alexander

[Constantin]

If relay speed is not a consideration, I would look into sourcing a relay board with built-in optocouplers. They are inexpensive, plentiful, etc. and provide convenient terminals to interface with. If you need to switch power on and off several times a second, you'd have to consider something solid state, like a MOSFet. Not my area of expertise.

Ideally, the Teensy and the board/motor power will be 100% separate - hence my suggestion re: a opto-coupler. Inductive kickbacks, etc. can't hurt your Teensy as a result. Relay boards include terminals to interface with, so I'd stay away from line power and provide low-voltage power to the relay board instead. All terminals on the board will be electrically separate, so you can have one power supply per device, minimizing interference between them.