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Newbie question on WAM kit - servo tutorial — Parallax Forums

Newbie question on WAM kit - servo tutorial

carbonAgentcarbonAgent Posts: 4
edited 2005-11-12 17:04 in BASIC Stamp
Hello Forum,

·· I hope this is the right place to ask this question. I have recently started going through the servo tutorial in the WAM kit and I noticed that the schematic shows that the Parallax standard servo is powered from Vin rather than Vdd.·It·also includes a warning not to use the·Parallax·continous rotation·servo(which I recently ordered)·as the circuit may damage it. I looked up the specs on both servos and they both·carry ratings of 6 volts. So now I'm puzzled by a few things. Why can't I use both servos for these example·circuits if they have the same rating? Why am I hooking up the servo to Vin instead of Vdd? Isn't Vin a direct connection to the 9 volt battery -·which is over the power rating of the servo? And finally, what would happen if I used Vdd to·power the servo? Would this damage the board. btw -·I am·doing the projects on·the·homework board. If anybody could help with these questions it would be much appreciated,

Thank you!

-Charles

Comments

  • Steve JoblinSteve Joblin Posts: 784
    edited 2005-11-12 00:16
    It's not the volts, it is the amps... driving the servo draws too much current and cause the stamp to possibly reset. What you want to do is have two separate power sources (one for the stamp) and one for the servo. Just make sure that you tie the grounds together!

    I find that a 9v works great to power the Stamp, but I use several AA batteries (4 to 6) to power the servo (use 6 AA's if they are Ni-MH rechargeables since they only provide 1.2 volts, as compared to a standard AA battery that provides 1.5 volts).
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-11-12 00:40
    Actually, in this case it is the volts...You really shouldn't apply more than 6 volts to most servos.· The bottom line is, in this particular case the standard servo, but not the contiuous rotation servo can be used at the 9 volts for the limited applications of demonstrating it's use on this board.· Obviously, if you intended to use the servo in some sort of application it should have a 6 volt supply.· Remember, in the WAM Kit, the servo is provided for learning purposes.· Running it contiuously on 9 volts would gradually reduce it's useful life.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • carbonAgentcarbonAgent Posts: 4
    edited 2005-11-12 17:04
    Thank you!
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