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Servo not running — Parallax Forums

Servo not running

jaegjaeg Posts: 156
edited 2005-10-11 05:35 in Robotics
I have the ground to the servo connected to a pin so the stamp can trigger it.· I was told that you need to have servos powered by a seperate battery because it will use too much of the stamps power but when I use pulsout the servo will only use the same battery as the ground.· How do I fix this so it won't drain the stamps battery?

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-09 01:36
    You cannot connect the servo in that manner.· I don't know why you would want to disable the servo by turning off it's power, but if that's what you really want to do then you should connect the servo ground wire to the collector of an NPN transistor capable of handling the servo's max stall current.· The emitter would be connected to the common ground.· The base would be connected through a resistor (probably 1K) to the Stamp I/O pin.· Never connect a high-current device directly to an I/O pin unless you don't really need that pin again.· =)

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • bulkheadbulkhead Posts: 405
    edited 2005-10-11 01:12
    Wait, let me see if I understand this correctly. The proper way to connect a servo is to connect the black and red wires of the servo to a separate battery from the stamp, connect the black wire of the servo's battery to the ground (black wire also) on the stamp's power source, and connect the white signal wire to the stamps I/O pin?

    If this works, would it be possible to run the servo and the stamp off of the same battery as the stamp (given that that battery could provide enough current for both)?

    Thanks.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-11 05:35
    Yes, and maybe.· Yes the connections for the servo are okay...But you can use the same power source.· The problem here is that you're trying to connect and disconnect power to the servo, which may or may not cause glitches in the power system.· Depending on how low it was, it could brown out the Stamp's power.· How much voltage were you planning on running them off?· What current?

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
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