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Thread: FB3 Power

  1. #1
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    Default FB3 Power

    I'm sure I saw a post somewhere about being able to power the FB3 via a second USB lead, but for the life of me I cannot find it

    Was I dreaming?

    Jim

  2. #2
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    Default

    On the older FB3's you can power the FB3 over the USB just by adding a jumper/bridge on the board.
    Best to find out fom Bill if you can do the same with your newer FB tho...

  3. #3
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    Default

    Hmm this would have been good to know about a while ago.... but then again the extra 5v supply I have is helping out elsewhere.

  4. #4
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    Hi Jim

    I'm wondering why you want to use a second USB lead to provide power when the single one should cover it?

    I did think about going this route myself but have plumbed for the 'wall wart' route as it's easy to implement, and easy to fix/replace if it ever goes wrong. Given the variety of USB ports out there I'm not sure i trust them to provide the power.

    On a similar vein, would a 300mA supply do it, or should I go for 500mA? Bill did say that it was under 100mA when running on card and about 300mA on USB, so would the 500 give some safety margin?

  5. #5
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    Default

    I used my laptop's USB ports as the power source for my FB3 while I was traveling with Unce Sam last summer - I just wired in a second USB cable and plug to the power input terminals on the FB3.

    I never had any problems with the arrangement, but I was also careful to make sure I didn't have any other USB-powered devices plugged into the laptop at the same time (I didn't want to put too much load on the laptop's 5 volt supply on the USB bus). If you want to go this route but are concerned about overloading your computer's power supply, using a USB hub with its own power supply (instead of powering directly from the computer's USB ports) will probably work fine.

    RR
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  6. #6
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    Running LiveQ and without the projector plugged in its drawing just over 300mA according to my bench PSU.
    I'd go for the 500mA supply.

    Jim

  7. #7
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    Hi all,

    You can "bus power" a FB3 pretty easily. On the newer ones, with USB "B" connector on the daughter board, there are two gold through-hole pads. They are the only two gold through-hole pads. If you put a wire there, it will allow you to bus-power the FB3.

    Once enumarated, a USB device may draw up to 500mA (as long as it has been given permission to do so by the driver and PC root hub).

    In any event there is one thing to keep in mind. If you bus-power the FB3, we HIGHLY recommend that you simply remove the other power wires from it. Otherwise you will have a kind of collision between some external power supply, and the PC's USB power.

    Bill

  8. #8
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    Bill, not quite sure what you mean by 'through-hole pad'

    Can you point out which bit in the photo if its visible please?

    Are they the 2 very small holes running vertically, just to the left of the horizontal silver oval thing on the usb daughter board? (do you love my technical descriptions?)
    Attached Thumbnails Attached Thumbnails DSC00132.JPG  


  9. #9
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    Norty
    I have marked a pair of pads from your pic - they are gold and are through hole plated as Bill said there are only 2 pads like this I would take it that these should be the ones you want. May be worth testing them with a meter (continuity) to be certain
    Rob
    Attached Thumbnails Attached Thumbnails DSC00132.JPG  

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  10. #10
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    Yep, those are the holes. Just MAKE SURE you don't connect the FB3 to the normal power supply when this wire is in place.

    Also, this can be done on old FB3 as well, but the place where you put the jumper is not as obvious...

    Bill

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