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LED stuck ON — Parallax Forums

LED stuck ON

xanaduxanadu Posts: 3,347
edited 2012-08-29 02:16 in General Discussion
Ever since the lights flew over last night this has been happening.

[video=youtube_share;_Mt1B40F0No]

Comments

  • Clock LoopClock Loop Posts: 2,069
    edited 2012-08-25 18:00
    Capacitor C2, which is a 1000uF, and C1 which is also 1000uF.

    This is enough charge to dimly light a led. I have the same BOE, bs2 board, but I never noticed it keep charge like that. It will eventually discharge.

    http://www.parallax.com/Portals/0/Downloads/docs/prod/boards/BOE_USB_D_Schematic.pdf
  • RDL2004RDL2004 Posts: 2,554
    edited 2012-08-26 05:22
    The LED is powered from VDD (as is everything else on the board). It normally goes out a split second after power is removed. I suspect there is some trickery going on here.
  • skylightskylight Posts: 1,915
    edited 2012-08-26 06:55
    That LED stays bright for a long time! Are you sure you havn't got one of those perpetual energy machines there? :smile:
  • ercoerco Posts: 20,259
    edited 2012-08-26 21:56
    If it were me, I'd hide a battery under the Stamp. :)
  • TtailspinTtailspin Posts: 1,326
    edited 2012-08-26 22:05
    Think that's the new BS2 rev Q, You just have to shake it for a couple minutes after the ball starts to rattle...:thumb:


    -Tommy
  • davejamesdavejames Posts: 4,047
    edited 2012-08-27 08:36
    ...and the BOE power switch is OFF, so maybe Xanadu has some sort of nifty flourescent emitting diode (aka FED) and has a local transmitter keyed up?

    BTW - what lights flew over?
  • xanaduxanadu Posts: 3,347
    edited 2012-08-27 09:07
    davejames wrote: »
    BTW - what lights flew over?

    I had to run to get my camera but I did manage to get this shot.

    stange light.png
    stange light.png
    603 x 476 - 4K
  • skylightskylight Posts: 1,915
    edited 2012-08-27 14:25
    UFO or UPP?

    Unexplained Parallax Phenomenom
  • ercoerco Posts: 20,259
    edited 2012-08-27 14:31
    @xanadu: pull out the Stamp and make a new video... :)
  • skylightskylight Posts: 1,915
    edited 2012-08-27 15:13
    perhaps it's an OLED?

    Obscurely Lights Every Day
  • xanaduxanadu Posts: 3,347
    edited 2012-08-27 16:07
    erco wrote: »
    @xanadu: pull out the Stamp and make a new video... :)

    I thought it would be dimmer by now, you know, after the ships left.

    [video=youtube_share;oaN2924Oges]
  • ercoerco Posts: 20,259
    edited 2012-08-27 16:41
    Man do you ever work fast! :)
  • skylightskylight Posts: 1,915
    edited 2012-08-27 16:45
    you realise we are not going to be satisfied until every component bar the LED is removed including the breadboard.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-08-27 16:52
    Make another video with an RF field meter visible in the frame. (LEDs are diodes, after all, and diodes are RF detectors.)

    -Phil
  • skylightskylight Posts: 1,915
    edited 2012-08-27 16:55
    similar principle to flourescent tubes lighting near power lines?
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2012-08-27 16:56
    Curious that you don't see the capacitor solder points on the back side of the PCB. My BOE is the original and has a rubber backing so I can't compare...

    EDIT: I take that back - I do see them but they look strange. It looks like the one on the outside edge has both wires soldered to ground??
    Multi-layered board?

    EDIT: from the schematic it looks like one 1000uF cap is directly across the LED and voltage regulator
    http://www.parallax.com/Portals/0/Downloads/docs/prod/boards/BOERevC.pdf
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2012-08-27 17:14
    I wondered if he might have drilled out one of the caps from the bottom and inserted a lithium battery. I'm sticking with the RF field hypothesis, though.

    -Phil
  • skylightskylight Posts: 1,915
    edited 2012-08-27 17:17
    could you take a voltage reading across the LED but still show it lit at the same time? I'm thinking if induced then a meter reading will drag the volts down
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2012-08-27 17:38
    Phil Pilgrim (PhiPi) wrote: »
    I wondered if he might have drilled out one of the caps from the bottom and inserted a lithium battery. I'm sticking with the RF field hypothesis, though.

    -Phil

    Do they make Supercaps in the same shape as a regular electrolytic???

    EDIT: Found a 1 farad supercap at Digikey http://www.digikey.com/product-detail/en/EEC-A0EL105/P6963-ND/125034
  • xanaduxanadu Posts: 3,347
    edited 2012-08-27 17:41
    skylight wrote: »
    could you take a voltage reading across the LED but still show it lit at the same time? I'm thinking if induced then a meter reading will drag the volts down

    [video=youtube_share;gLr2t42Bc2s]
  • xanaduxanadu Posts: 3,347
    edited 2012-08-27 18:00
    skylight wrote: »
    you realise we are not going to be satisfied until every component bar the LED is removed including the breadboard.

    In EMIC 2's voice, "No disassemble Bs2 Board."
  • ElectricAyeElectricAye Posts: 4,561
    edited 2012-08-27 18:18
    I won't be happy until the board is inside a faraday cage.

    And you've got garlic hanging around its neck.
  • TtailspinTtailspin Posts: 1,326
    edited 2012-08-27 18:26
    If the videos had sound, you would be able to hear the ball rattling around when the board is flipped over...:cool:


    -Tommy
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2012-08-27 18:35
    I stuck 1 Farad 5.5V Supercap, 470 ohm resistor and an LED on a breadboard.

    I charged the supercap with a battery pack and then pulled the battery wires.

    The LED stays lit for at least 10 minutes.
  • xanaduxanadu Posts: 3,347
    edited 2012-08-28 10:41
    --Spoiler Alert--

    That BS2 BOE held up well. It still works but I managed to loosen the breadboard holes a tad too much, so I ordered another breadboard for it.

    In the meantime I pulled out all of the conductor strips inside of the white plastic, jammed a CR2032 battery in and squeezed the wires between the VIN and VSS headers so they touch in the small gap between the board and header.

    In the last video I tried to make it more obvious what I had done. It wasn't anything as elaborate as some people thought but thanks for playing along!
  • Ron CzapalaRon Czapala Posts: 2,418
    edited 2012-08-28 11:24
    Good one! I captured the first YouTube video and played it in slow motion looking for unusual things.
    Not a whole lot of places to hide a power source.
    I thought the color of solder on one of the capacitors looked a bit darker so that's why I suspected a supercap inside the original can...

    Thanks for not leaving us hanging:smile:
  • skylightskylight Posts: 1,915
    edited 2012-08-29 02:16
    Ah shame you gave it away so early as I only just saw the video of the voltage reading which made me suspect a battery somewhere, I did have suspicion that the breadboard might be hiding something hence why I asked you to remove it.
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