RSS
A desktop fridge made from a peltier cooler which the builder insists can be powered through a USB port (though I wonder).
$5 Mini USB Fridge! - Link
USB-powered desktop cooler
Posted by Gareth Branwyn |
Nov 28, 2007 09:35 AM
DIY Projects, Instructables |
Permalink
| Comments (5)
| Email This |
| Digg this!
Recent Entries
- 3D renderings of the Mandelbrot set
- New in the Maker Shed: Microbe Motel kit
- Science through graphic novels
- Tiny solar-powered brass engine in a wineglass
- Maker Shed kiosks at Fry's
- New hackerspace in Chicagoland: Workshop 88
- Mint tin electronics dev kit packs the essentials
- Olympus BioScapes competition winners
- Mac mailbox
- LHC tweets its first circulating beam of 2009
Comments
Oldest comments listed first.
Leave a comment
Subscribe to MAKE Magazine!
Subscribe today, save 42% and get web access to MAKE free. MAKE Digital Edition is available only to subscribers.
$34.95 / 1 year
(4 Quarterly Issues)
While lots of things can be powered through a USB port, the danger of killing your power supply isn't worth saving $3 or pulling a wall-wart out of your junk pile.
Since he didn't say, and since someone might try it, DO NOT use a laptop with this.
Reply to this comment
to optimize cooling, just turn the whole thing, because cold air descends and hot air ascends.
Reply to this comment
You could put your computer in the cooler and over clock it...
Reply to this comment
The USB 2.0 standard stipulates that Host ports (like the USB ports on your computer) must provide 5V at 500mA (or 2.5W) per port, to power mice, keyboards etc.
So the cooler will work....a little.
My Maxtor desktop backup drive uses two USB cables; one for USB and power, the other one just for power. In theory you could plug the cooler in to all USB ports, and get 6x2.5=15W.
Important note: some notebooks assume you'll never use all ports at max power all the time! So don't use your laptop as a portable 5V power supply. Then again....
Reply to this comment
wsuverkropp says, "The USB 2.0 standard stipulates that Host ports (like the USB ports on your computer) must provide 5V at 500mA (or 2.5W) per port ..."
That's not the whole story.
Per the USB spec, the port provides up to 100 mA before a device is plugged in. Once a device is plugged in, it is enumerated (the computer asks the device what it is, etc) and the device tells the host how much current it needs, up to 500 mA. If the device asks for more than 100 mA and if such current is available (and you cannot get more than 100 mA per port on a bus-powered hub or some laptop ports when on battery power), only then will the computer allow the device to draw more than 100 mA. If the device requests more than 100 mA and that current is not available, the device is shut down.
Back to "USB Powered" Coolers, lamps, and other such things that completely violate the USB spec: since these things aren't true USB Devices and as such are not enumerated, the maximum current available to them will be 100 mA. The rub is that these things don't have any current limiters or protection, so hopefully they won't damage your computer's USB ports.
Reply to this comment