USB Voltage: This will challenge the greatest mac minds here!

Discussion in 'Mac Accessories' started by IraeDeorum, Jan 25, 2007.

  1. IraeDeorum macrumors newbie

    Joined:
    Nov 7, 2006
    #1
    Okay, here's the dilemma: I want to buy a USB cup warmer.

    (http://usb.brando.com.hk/prod_detail.php?prod_id=00012)

    Not so big of a deal right? The only problem is that I want to have some control over how it heats so I was wondering if there is anyway to change the outgoing voltage from your USB ports through a software or hardware interface. I have looked all over the web and haven't come up with any results. I would prefer a software solution but as I said hardware will also work. I may just be stupid and the solution is really easy.
    Anyway, thanks for any help,

    -Chris

    PS: Is it even possible to control voltage through a USB connection without hardware only software?
     
  2. Eraserhead macrumors G4

    Eraserhead

    Joined:
    Nov 3, 2005
    Location:
    UK
    #2
    I wouldn't have thought it was changeable without hardware, in that case you wouldn't be able to use the USB port properly. You could use a capacitor to increase the voltage, but that's kinda pointless as what the cup warmer needs is more power (current x voltage).
     
  3. IraeDeorum thread starter macrumors newbie

    Joined:
    Nov 7, 2006
    #3
    Update

    Actually, I want to lower the temperate to about 90F (32C) not raise it.
     
  4. sycho macrumors 6502a

    sycho

    Joined:
    Oct 7, 2006
    #4
    [​IMG]

    left side to 5V USB supply, right side to common, bottom to where the cup would normally connect to the 5V wire. :)
     
  5. IraeDeorum thread starter macrumors newbie

    Joined:
    Nov 7, 2006
    #5
    I really want to be able to regulate the temperature so I think I would need a switch of some kind. As I said before, I would really prefer a software solution, if possible. If not, I'll probably buy an electric one and regulate it with a dimmer of some kind. Thanks though.:)
     
  6. tominated macrumors 68000

    tominated

    Joined:
    Jul 7, 2006
    Location:
    Queensland, Australia
    #6
    beat me to it. get an old usb extention cable and cut of it's sexual organs (lol). attatch it to a potentiometer or resister (i dunno which wires). away we go! BTW: a dimmer is just a potentiometer. that symbol is the circuit diagram sybol for a potentiometer
     
  7. sycho macrumors 6502a

    sycho

    Joined:
    Oct 7, 2006
    #7
    I'm sorry, but the USB specs aren't going to bend for you just to control the temperature of some coffee.

    That is the simplest way to do it. I volume control works in the same fashion and one out of a broken/unused stereo will work great. If you want regulation, then I'd suggest taking an electronics course and learning it. It's really not that hard once you understand the basics of electronics, but understanding the basics is the most important part.:)

    Actually a dimmer has a triac in it, as they switch AC and produce very little heat. I'm an not totally certain that a dimmer would work properly with a DC voltage, but a rheostat certainly would.
     
  8. dllavaneras macrumors 68000

    dllavaneras

    Joined:
    Feb 12, 2005
    Location:
    Caracas, Venezuela
    #8
    Would this USB cup warmer work on a hub or just on a built in port? How much power does it use?
     
  9. Copland macrumors regular

    Copland

    Joined:
    May 26, 2006
    Location:
    Rochester, NY
    #9
    I doubt a dimmer would work. And a rheostat seems a bit excessive: I don't see why a potentiometer wouldn't work. But, I really doubt there is a software way to reduce the voltage of a USB port.
     
  10. sycho macrumors 6502a

    sycho

    Joined:
    Oct 7, 2006
    #10
    Rheostat, pot, same thing :p
     
  11. ITASOR macrumors 601

    ITASOR

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    Mar 20, 2005
    Location:
    Oneida, NY
    #11
    You could just unplug it every once and a while when it starts to get too hot.
     
  12. IraeDeorum thread starter macrumors newbie

    Joined:
    Nov 7, 2006
    #12
    Thanks for all of your comments concerning my dilemma. Just as a side note, why can't you control voltage through the USB port with software?:confused:
     
  13. sycho macrumors 6502a

    sycho

    Joined:
    Oct 7, 2006
    #13
    Because it is a fixed set of specifications. Kind of like how you can not change the voltage coming out of you outlets, it will be fixed at 120VAC or 220VAC.
     
  14. Aperture macrumors 68000

    Aperture

    Joined:
    Mar 19, 2006
    Location:
    PA
    #14
    Idea! Try plugging it into a USB hub(make sure it is a POWERED one w/ a Power Supply). Then regulate the power going into the hub with a dimmer.. Would that work?
     
  15. sycho macrumors 6502a

    sycho

    Joined:
    Oct 7, 2006
    #15
    Simple version: NO.

    Please don't ask for the technical version, lots of explaining.
     
  16. iW00t macrumors 68040

    iW00t

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    Nov 7, 2006
    Location:
    Defenders of Apple Guild
    #16
    How about you just splice apart the USB cable, look for the 5V line in it, and put a rheostat across that?

    For better measure instead of plugging it into a usb port, buy one of those iPod chargers instead to prevent your logic board blowing up.
     

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