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BS homework board Question — Parallax Forums

BS homework board Question

um..., Hium..., Hi Posts: 64
edited 2005-05-05 00:19 in BASIC Stamp
i have the BS homeworkboard and i created another board to plug 9 servos into and when i hook up the - and + leads to the BS bread board it just goes dead but when i hook it up to a separate 9v it works fine. how can i make it so i dont have to use the seperate 9v?

Thanx for any help,
Mike M.

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Comments

  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-05-04 05:10
    Theres no way a 9V battery can handle driving 9 servos and a stamp without the stamp resetting itself, thats just way too much current for it to handle.
  • um..., Hium..., Hi Posts: 64
    edited 2005-05-04 13:39
    ok thanx i will just use a second power source. thanx for all your help!

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  • allanlane5allanlane5 Posts: 3,815
    edited 2005-05-04 13:42
    If you're really trying to control 9 servo's, I allow 150 mA per servo -- that's 1.350 Amps. If you don't need to move all 9 at the same time, MAYBE you can get away with a 1-amp supply. Still, you need a 9-volt 1 amp supply at least.
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-05-04 14:02
    Hello,

    ·· Even a (standard) 9V battery as a power source for your servos isn't going to be adequate if you're running them at the same time.· You should definately seek a power source with more current capacity available.


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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • um..., Hium..., Hi Posts: 64
    edited 2005-05-04 15:53
    i only need to run 1 at once. so i will just buy a 9v harnes and use that
    Thanx

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-05-04 17:43
    9V batteries are notorious for not having much capacity, If you rip apart a standard 9V alkaline you see six AAAA batteries strung in series. An AAAA battery is about half the diameter of a AAA and slightly shorter, if you want to keep with batteries and want to be able to run your servos for more than a few hours you should look into a 6 AAA battery pack to create 9V that will last more than twice as long as a 9V battery.
  • um..., Hium..., Hi Posts: 64
    edited 2005-05-05 00:05
    would it fry the servos to put a 12v power supply instead of a 9v?

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  • allanlane5allanlane5 Posts: 3,815
    edited 2005-05-05 00:19
    Well, if you put the 12-volts directly to the servo (by hooking the Servo to 'Vin') then yes, it would fry the servo.

    If you put the 12-volts through a regulator first (by hooking the Servo to 'Vdd' -- I believe there's a jumper for this on the BOE), then the Servo would be driven by the 5-volt output of the regulator, and it would not fry. In fact it would work fine.

    Note the BOE regulator IS limited to 1 amp -- but that's not much of a limit in your application, apparently.

    Note also the Servo has three wires. One goes to Vss (ground, usually black). One goes to Vdd (usually red). One goes to the signal pin of the BS2 (usually white).
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