Voltage to Servos

Joe FishbackJoe Fishback Posts: 99
edited 2004-10-26 - 17:39:35 in Robotics
I would like to run my servos from the ports on the BOE. I would also like to run the servos at 7.2 V and the BOE at 9 V. The jumper located between ports 13 and 14 can be used to select Vin or Vdd for the servos, but if I use 9 V and set the jumper to Vdd, you will have only 5 V going to the servos. Am I correct it in following thinking to run the servos at 7.2 V? Remove the jumper completely, supply +7.2 V to the center pin (where the jumper goes) from external supply and then connect the ground of the 7.2 V source to Vss on the BOE. Will this be OK, I do not want to burn anything out?

Joe Fishback


  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2004-10-26 - 00:10:59

    ·· Yes, the center pin the the Vsvo or Servo Voltage input...It's only connected when the switch (On Rev C.) BOE is in the third position.· You can drive the servos with the 7.2V and run the BOE off the 9V battery.· In fact, if you're going to have 4 servos this is probably a better idea anyway, as it will prevent dropout on the BOE's supply.

    Chris Savage

    Knight Designs
    324 West Main Street
    P.O. Box 97
    Montour Falls, NY 14865
    (607) 535-6777

    Business Page:·· http://www.knightdesigns.com
    Personal Page:··· http://www.lightlink.com/dream/chris
    Designs Page:··· http://www.lightlink.com/dream/designs
  • allanlane5allanlane5 Posts: 3,815
    edited 2004-10-26 - 17:39:35
    I just got back from the Futaba website: http://www.futaba-rc.com/faq/product-faq.html#q26

    They recommend you use their servo's with 4.8V (4 NiCD) or 6V (4 Alkaline, or 5 NiCd). I don't know what will happen at 7.2 volts on a Servo. Also, note that a 7.2 volt un-regulated DC wall-wart will put out more than 7.2 volts until fully loaded.

    Just so you are aware. It is a very good idea to go to the Servo Vendor's web-site to verify what you are doing. I chose Futaba because that's what Parallax sells.
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