Selecting an AC/DC switching power supply

Discussion in 'General Electronics Chat' started by kballing, Jun 21, 2007.

  1. kballing

    Thread Starter Member

    Jun 18, 2007

    I am designing a device that will need to convert from AC (110V 60hz from normal wall socket) to DC power. The device drives two electric motor pumps and a small circuit for timing valves and other pneumatics. I'm very new to all of this but have a basic understanding of electronics. I know that lots of different boards are out there. Each motor requires 12V and about 22W of power. The circuit can run on 5V I also have the option of getting AC versions of the motors. Since I have no experience in this, is there anything in particular I am looking for in an AC/DC switching supply? Is it better to use AC motors over DC? A similar device uses on AC pump and one DC pump. So I'd really appreciate if someone with more experience than I could help me out.


    P.S. Is in necessary or a good idea to use and additional rectifier before powering my circuit?
  2. Papabravo


    Feb 24, 2006
    I think that running motors from a switching power supply can be problematical. A load transient, when a motor turns on, can cause some switching regulators to fold. Their output drops until the motor gains some speed and the regulator can adjust.

    Motors don't really need regulated supplies. An unregulated supply from a transformer and a full wave rectifier will work just fine.
  3. Uman


    May 2, 2004
    Mixing a motor can cause problems with sensitive electronic devices on the same circuit or power supply, when the motor field is energized, de-energized and surges. EMI noise is generated and requires additional filtering. If motor precise speed control is not required, It would be perfered to run the motor from AC power. Use the switching power supply to power the DC devices and use a relay to contol the motor on/off.
    Check out these power supplies:
    They start at $9 for 5 watts.