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BS2 HomeWork Board — Parallax Forums

BS2 HomeWork Board

piguy101piguy101 Posts: 248
edited 2011-07-26 13:07 in General Discussion
I have the BS2 HomeWork Board Rev. E, and I want to know if I can power it from another source other than a PP3 (9-Volt) battery. If so, what is the safe voltage range I can use?

Comments

  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-07-25 19:43
    If it's not greater than that 9V then you're "safe".
    What're you figuring to do? HWBs don't have jacks.
    "Flying leads", alligator clips from a wall-pack? I like alligator clips, but you better know what you're doing.
    If you look in my pictures in my "profile", you can see a little power module I made for HWBs.

    PE - 'project pics' album
  • ercoerco Posts: 20,261
    edited 2011-07-25 23:11
    And remember: if you attach a 9V battery connector to the HW board's battery snaps to connect a power supply to the wires, the color coding gets reversed. Black goes to positive supply Vdd, red to ground Vss.
  • piguy101piguy101 Posts: 248
    edited 2011-07-26 04:08
    I was thinking of using a wall power supply regulated by a LM317 to power the board for extended durations, but the power could have a slight ripple or noise on it, would this affect the BS2?
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-07-26 05:36
    The 317 should iron out any ripple, practically.
    The wall-pack likely has a smoothing cap in it.
    There's a 7809 available, too (fewer parts req'd that way.)
  • piguy101piguy101 Posts: 248
    edited 2011-07-26 09:39
    Didn't think of the 7809 and that would be easier.

    EDIT: I looked through my junk drawer and found a 7908, would this work without damaging the BS2?
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-07-26 10:10
    A 7908 is a "-8V" (negative eight) regulator.

    If you run its "GND" to V_in and its output to V_ss then that "would work".
    But, I'd prefer that you not do that.
  • piguy101piguy101 Posts: 248
    edited 2011-07-26 11:01
    Oh, my bad it is a 7808 not a 7908. So you are saying 8V should be fine?
  • PJAllenPJAllen Banned Posts: 5,065
    edited 2011-07-26 13:07
    +8V -- That'll do.
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