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server question please help — Parallax Forums

server question please help

waynefoxwaynefox Posts: 19
edited 2005-08-11 21:27 in Robotics
i have a couple of servers like from a cd player and such will they work just the same as the continus motion servers from parallax

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wayne fox 3

windows and linux user
computer and robotics hobbyist
all around nice guy
check me out here at myspace.com/waynefox3

Comments

  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-08-09 11:02
    Wayne -

    I think you mean to say "servos" not servers. I doubt that you'll find any r/c servos inside a CD player. The r/c servo is the basis for the continuous motion motor that Parallax sells. The "r/c" refers to radio control, which is how r/c servos are usually used. When used in robotics for drive motors, they are controlled directly, however, not via radio control.

    Indeed you my find various types of DC motors inside a CD player, but they don't operate in the same manner as an r/c servo. You may find permanent magnet (PM) DC brush motors, brushless DC motors, DC servo motors, or you may find stepper motors inside such devices. Any/all are controlled in a different manner than r/c servos.

    Generally speaking small motors with only two leads are PM DC brush motors. Those with 4, 6, or 8 leads are generally stepper motors, and those with an odd number of leads may be DC brushless motors, or DC servo motors. It's best to find the nameplate, if one exists, and research the motor that way.

    Regards,

    Bruce Bates
  • Tricky NekroTricky Nekro Posts: 218
    edited 2005-08-09 12:58
    Bruce

    What do you mean by brushless (sorry but for my bad english)



    Provas

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    -Rule your Destiny-
    --Be Good. Be Bad. Be Provas--
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-08-09 14:27
    Provas -

    Older PM DC motors and even many recent, inexpensive types have brushes which act as commutators, supplying power to each of the appropriate armature segments, in turn. as the armature rotates. There are some obvious downsides to such a set up, but one of those which may not be apparent is the inability to smoothly and precisely control the motor using a simple feedback mechanism which is internal or, integrated with, the motor.

    In a brushless DC motor the "commutation" (albeit non-contact) is usually done using Hall effect sensors to detect magnets which are attached to the rotating armature. Power is thus applied to the appropriate external coils, governed by the Hall effect sensors, causing the armature to rotate. The brushless DC motor can almost be viewed as a DC brush motor constructed ... inside out!

    Below are some links you may find helpful in further explaination. Here is a rather elementary web page with many good examples, illustrations, and discussions about the various types of DC motors, how they operate and what the advantages and disadvantages of each type are:
    http://my.execpc.com/~rhoadley/magdcmot.htm

    Here is a tutorial on just brushless DC motors (BLDC) which is short, but quit complete, even in its brevity:
    http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=02nQXGrrlPY7r8hv0V

    I hope that is helpful.

    Regards,

    Bruce Bates
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-08-09 14:45
    http://www.makingthings.com/products/documentation/app_notes/motors_general.htm
    http://www.freescale.com/files/microcontrollers/doc/app_note/AN1627.pdf
    http://www.electricmotors.machinedesign.com/BDEList.aspx

    Order in ease of use (from the perspective of a basic stamp)
    1. Brushed DC motor
    2. Servo
    3. Stepper Motor
    4. Brushless DC motor

    A stepper is a special type of brushless.

    A brushed motor has brushes which make contact with the commutator, energizing the windings in the rotor which causes a magnetic feild in the rotor·to interact with stationary permanent magnets in the stator, resulting in rotation. So in brushed motors the rotor's magnetic feild changes polarity and the stator's magnetic feild is constant.

    A brushless motor reverses the two, the rotor has a permanent magnet(s), and the stator has windings whose magnetic feild is alternated to make the rotor spin.

    The position of the rotor is inherently known in a brushed motor, therefore a simple DC current is all that is needed for the motor to run. The position of a rotor must be determined in a brushless motor in some manner in order to determine when the stator windings must be switched on or off, and therefore requires a special driver circuit in order to operate.

    Motor Terms Glossary·


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    ·1+1=10

    Post Edited (Paul Baker) : 8/9/2005 2:49:15 PM GMT
  • waynefoxwaynefox Posts: 19
    edited 2005-08-09 18:35
    well thanks ill have to get some cash and get me some servos from parallax then
    (bad spelling was due to being up really late)

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    wayne fox 3

    windows and linux user
    computer and robotics hobbyist
    all around nice guy
    check me out here at myspace.com/waynefox3
  • waynefoxwaynefox Posts: 19
    edited 2005-08-09 20:13
    i have another question if its not to much trouble i just found a 9v 100 mA wall adapter that was used to charge a watch i had that no longer works could i use that for the board i have its the homewrok board i got with the what is a micro controler kit

    could i use that and it not dammage the board or could i safely use that with it i should i say

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    wayne fox 3

    windows and linux user
    computer and robotics hobbyist
    all around nice guy
    check me out here at myspace.com/waynefox3
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-08-09 20:19
    I dont think you would damage anything, but the power supply would not be able to power anything beyond the stamp. The 100mA is too low of a current for the majority of applications. Additional devices such as your servo would overtax the power supply.

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    ·1+1=10
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-08-09 20:33
    I purchased the universal camera power supply from my local Radio shack, it can be switched between several different voltages from 3V to 7.5V and can source 2 amps of current. It comes with 3 different plug types, one of which works with Parallax's power socket, additionally they have about 20 different plug types which can be used with the adapter (availible seperately). Just be sure you insert the plug with the + terminal going to the inside of the plug. I use this single power supply for all of my electronic devices, including Parallax's products and have never had a problem. @ $28 it isn't cheap, but as long as you don't do anything stupid with it, you won't have to buy another AC adapter again for all but the strangest electronic components. (ok so a 9V electronic device isnt strange, but you know what I mean)

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    ·1+1=10

    Post Edited (Paul Baker) : 8/9/2005 8:39:23 PM GMT
  • waynefoxwaynefox Posts: 19
    edited 2005-08-09 21:28
    so basicly no servos no problems?

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    wayne fox 3

    windows and linux user
    computer and robotics hobbyist
    all around nice guy
    check me out here at myspace.com/waynefox3
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-08-09 21:58
    Wayne -

    The r/c servos can obtain their power from a separate power supply sometime in the future, if you wish. Just remember to tie the ground from that r/c servo power supply back to the Stamp ground, so all the grounds are common.

    Regards,

    Bruce Bates
  • waynefoxwaynefox Posts: 19
    edited 2005-08-09 22:05
    bruce

    was that in regards to the servo question or the power adapter i found

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    wayne fox 3

    windows and linux user
    computer and robotics hobbyist
    all around nice guy
    check me out here at myspace.com/waynefox3
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-08-09 22:18
    Wayne -

    Either ot both. Any power supply, other than that which operates the Stamp, which supplies power to any peripheral devices will need to have its ground tied back to the Stamp ground. The isssue is not specific to r/c servos, it applies to any DC device which will be controlled by the Stamp via the I/O pin ports.

    Regards,

    Bruce Bates
  • waynefoxwaynefox Posts: 19
    edited 2005-08-10 03:36
    ok so just so im thinking correctly then any servo that i get works just as long as the grounds are common and everything is correctly wired

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    wayne fox 3

    windows and linux user
    computer and robotics hobbyist
    all around nice guy
    check me out here at myspace.com/waynefox3
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-08-10 05:22
    Wayne -

    Various r/c servos will have certain idisyncracies, but generally speaking what you said is correct. Due to the nature of how they are controlled (a variable length pulse of current) all r/c servos should react basically the same way, so long as they are wired correctly. There are many examples of using r/c servos in the free documentation provided by Parallax on teir web site.

    Regards,

    Bruce Bates
  • allanlane5allanlane5 Posts: 3,815
    edited 2005-08-10 14:36
    Wayne, what you said is true "any servo I get will work", assuming what you have is really an R/C servo. I'm certain anything coming out of a CD player will NOT be an R/C servo.

    It's much more likely to be a stepper motor of some kind, which are harder to interface.
  • waynefoxwaynefox Posts: 19
    edited 2005-08-10 18:37
    oh ok i got it now thanks i wouldent want to mess up my stamp or anything ill have to work on getting me some servos from parallax then

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    wayne fox 3

    windows and linux user
    computer and robotics hobbyist
    all around nice guy
    check me out here at myspace.com/waynefox3
  • waynefoxwaynefox Posts: 19
    edited 2005-08-10 19:12
    i would like to ask this i have a small cpu fan and a small hovercraft came to mind could i run that fan with the stamp
    and a battery the fan is 12 v 0.11a

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    wayne fox 3

    windows and linux user
    computer and robotics hobbyist
    all around nice guy
    check me out here at myspace.com/waynefox3
  • Tricky NekroTricky Nekro Posts: 218
    edited 2005-08-11 15:41
    Yes, you can control the fan with one of the pins but your fan won't be able to reach its max RPM due to the voltage shortage, cause the Basic Stamp can't provide more than 5V at 20mA. Also, it could be difficult to move the hovercraft, even if the fan was at max speed, I'm about building my own hovercraft, believe me. You will be in·need of·a hair drier fan, but·also in need of more Amps, so think about the 2n series transistors (2n2222, 2n2219 and so on) or a H-Bridge for motor controlling, which you can build one easily. (I'll upload the schematic if you want)(with two L293DNE)



    P.S. Guys thank you for the above info given about brussless DC motors!!!

    Regards,

    Provas, Greecescool.gif

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    -Rule your Destiny-
    --Be Good. Be Bad. Be Provas--


    Post Edited (Provas) : 8/11/2005 3:54:26 PM GMT
  • waynefoxwaynefox Posts: 19
    edited 2005-08-11 21:27
    thanks for all your help guys im getting all kinda of ideas what i could do with some of thies stamps when i get some cash ill have some all arounfd my house controlling things with voice controle and stuff

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    wayne fox 3

    windows and linux user
    computer and robotics hobbyist
    all around nice guy
    check me out here at myspace.com/waynefox3
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