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BS2 to control OWI arm trainer — Parallax Forums

BS2 to control OWI arm trainer

kleekrukleekru Posts: 32
edited 2012-02-02 21:43 in BASIC Stamp
I've seen other similar posts but I can't seem to put my finger on exactly what I need to do to control this OWI robotic arm (simple DC with my BS2.
I've successfully driven one of the motors (the gripper) using a transistor and the 9V power from triggering a pin on the BS2, but I can't seem to get the same idea to work leveraging the 4 D Battery power in the arm itself. I've seen posts regarding using transistors, H-bridges, relays, etc... but would like to know the simplest and least costly of these options.

I already have the 2N2222 transistors and prefer to use them if possible (need some confirmation on how to wire them so I can leverage the Owi arm power, not the BS2 9V. If I need to buy an H-bridge, any suggestions on which one?

Thanks in advance!
Kevin

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2012-01-28 05:59
    From what I can see (at Pololu), that thing is controlled with switches, looks like they're centre-off types.
    Anyway, you ought to be able to use relays in their place, or in parallel, it's up to you.
    I don't know the current ratings of the OWI motors, but, depending, you might be able to get by with reed relays.

    More details, Kev.
  • kleekrukleekru Posts: 32
    edited 2012-02-01 16:19
    Thanks PJ... I think I'm on the right road. I was able to get the gripper for the arm triggered to open and close sending some HIGH/LOW signals to 2 input pins on the BS2. I did this using two SPDT relays from radioshack and the accompanying resisters and diodes... simple for many but an accomplishment for me. I think I can do most I need to do using these relays... but I'm interested in building out H-Bridges using some simple (and inexpensive) transistors (2N2222-NPN and 2N3906-PNP). I'll keep researching but if anyone has any warnings for me before I dive in... I'm very open to suggestions. I don't know the current ratings of the motors either. ... Might end up sticking with the relays... since they seem straight forward. Any thoughts?
  • ercoerco Posts: 20,257
    edited 2012-02-01 16:41
    Kevin: We can talk about relays later. I'm your huckleberry.

    First, buy this right now before somebody else (or me) does: http://www.ebay.com/itm/OWI-Robotic-Arm-Edge-w-USB-Kit-/190634990957?pt=LH_DefaultDomain_0&hash=item2c62bb1d6d

    $37 for the OWI edge robot arm AND USB computer interface. I have this and it works great. It will be gone within an hour, pounce right now or all is lost !
  • ercoerco Posts: 20,257
    edited 2012-02-01 16:49
    Hope you get that OWI arm. Here's a thread on relay H-bridges, a subject near & dear to my heart!

    http://forums.parallax.com/showthread.php?106382-4-State-Relay-H-Bridge
  • kleekrukleekru Posts: 32
    edited 2012-02-02 21:43
    Oh man... that was a good deal, but alas it's gone. Thanks for the inside track anyway. I abandoned the transistors and went back to the relays... which are working... now, time to program something interesting. I should probably start a different thread for this but I would love to control the BS2 using a PHP web page... any hints where to get the best insight for that?
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