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power supply for servo controller — Parallax Forums

power supply for servo controller

ToddHToddH Posts: 34
edited 2005-06-02 17:00 in Robotics
well, i thought I would leave the safty of the tutorials and kits and try my hand at creating a robot from scratch. yippy for me. I would like to try something that,perhaps, would require a number of servos. I see that parallax has a usb servo controller. It looks pretty cool (from my newbie eyes). I was reading through the docs and it says I need to supply my own power to the controller.

Here is the question.... how do I do that? What parts do I need and how do I hook them to the controller? If someone can point out a URL to what I need, that would be perfect [noparse]:)[/noparse]

Also, I see there is a usb and a serial version of the servo controller board. It looks to me like the serial version came first and then they upgraded the abilities with the usb version. The usb version comes with some point-and-click software which will allow you to come up with some sequences and then download them. More questions.... in the future when you can download the sequences... where do they get downloaded to? the SCB or to the board of education? If its the SCB, then how do I then have my program that I write and download to my BoE talk with the "code" or "sequence" that I just downloaded to the SCB? Does that make any sense?

sorry, I know its newbie stuff, but you all are great at answering these questions!

Todd

Comments

  • Ryan ClarkeRyan Clarke Posts: 738
    edited 2005-06-02 04:39
    Keep in mind that if you are using the USB servo controller you are going to be building a 'tethered' robot.

    Basically you need to decide what your power requirements are *first* then design a power supply...if you are building a free roaming bot (see above) then you will need some sort of battery pack. If you are going to power your motors/servos with the same source as your control electronics (not always a good idea, but not always a bad idea either) you'll most likely need a voltage regulator (like a 7805 or the like) and the supporting components (most likely a 'safety' diode, small cap, and resistors- the diode is to keep things from being hooked up 'backwards' and the cap to 'clean' the signal, as starting/stopping of motors and the like can cause spikes/brownouts)- Otherwise you're looking at a separate power for your control and a separate source for motors- (Take your 'typical' RC car, there is usually a set of batteries for motors, like D cells, and a 9v for your control system- that is just one example of design)-

    Hope this helps....

    Ryan
  • ToddHToddH Posts: 34
    edited 2005-06-02 12:26
    Oh, no - I don't want a tethered robot. I thought I'd build some sort of "walking" robot that is either IR controlled or autonomous. So that means I need the serial version of the servo controller?

    Concerning the power supply... The main hardware I see being used is: my board of education, the servo controller and about 6 servos. The BoE has its own 9v battery. Are you saying that I would need 1 more battery pack or possibly 2 more? (I think you are saying 1 more). Going on the 1 more theory... how do I determine what to hook up to it? Is it based totally on the number of servos I'm trying to drive?

    From this dullards perspective, it would be great if you could give me an example of what I would need to drive 6 parallax cont rotation servos.

    thanks!
  • ForrestForrest Posts: 1,341
    edited 2005-06-02 13:40
    I'm pretty sure the USB version of the Parallax Servo Controller can work either connected to a PC or it can be controlled with a Basic Stamp thru the serial interface on the controller. The USB version lets you create servo control programs on your PC thru a GUI interface - this isn't possible with the serial version of the controller.

    You'll need another power supply to drive the servo's. I'm sure other people can chime in here but I think a single 9V battery would only supply enough power for 2 servo's. For more information on power requirements - check out the manuals for Parallax's Quad Crawler and Hex Crawler robots.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-06-02 15:46
    And dont forget to tie the ground of the stamp and servo power supplies together.

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  • Ryan ClarkeRyan Clarke Posts: 738
    edited 2005-06-02 17:00
    Forrest is correct, the USB version allows you to create a movement sequence (via the software) and then have a BS2 run that sequence of movement- (this is also possible with the Serial PSC, but is more difficult to do, since you are creating the movements by hand, vs using the GUI software)-

    Sorry about that!

    Ryan
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