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Draft
Intermediate Member
Username: Draft
Post Number: 136
Registered: 7-2006
| | Posted on Monday, December 04, 2006 - 8:04 pm: | 
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For the past few months, I have been using "laptop coolers" under my heat-generating equipment with great success in keeping temperatures below 80 degrees (F). I have attached a couple of photos as examples. These units make great [inexpensive] Christmas gifts at about $30 with 2 exhaust (negative pressure) fans that run off USB-connector power. They may be available to run of 12-volt DC, but I have not seen anything that looks as "Clean" as these do. I was able to use the T/S bracket and screw into the top of the cooling unit to both secure and cool the 667V.
Moderator Note!
Please Submit all Personal Pictures of your Equipment to the: Members Pictures Area of the Copper Forum.
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Wildrat
Senior Member
Username: Wildrat
Post Number: 1171
Registered: 12-2003
| | Posted on Friday, December 08, 2006 - 11:12 am: |
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Got this off Google, basically it tells you that the USB port supplies 5vdc and that fans and other non-standard devices could cause problems. Read the article for the full story. I'd hate for any of you all to have problems with your computer and devices.
WR
Standard
The USB specification provides a 5 V (volts) supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.35 V between the +ve and -ve bus power lines.
Initially a device is only allowed to draw 100 mA. It may request more current from the upstream device in units of 100 mA up to a maximum of 500 mA. In practice, most ports will deliver the full 500 mA or more before shutting down power, even if the device hasn't requested it or even identified itself. If a (compliant) device requires more power than is available, then it cannot operate until the user changes the network (either by rearranging USB connections or by adding external power) to supply the power required.
If a bus-powered hub is used, the devices downstream may only use a total of four units — 400 mA — of current. This limits compliant bus-powered hubs to 4 ports, among other things. Equipment requiring more than 500 mA, hubs with more than 4 ports and hubs with downstream devices using more than four 100 mA units total must provide their own power. The host operating system typically keeps track of the power requirements of the USB network and may warn the computer's operator when a given segment requires more power than is available.
Non-standard
A number of devices use this power supply without participating in a proper USB network. The typical example is a USB-powered reading light; fans, mug heaters, battery chargers (particularly for mobile telephones) and even miniature vacuum cleaners are also available. In most cases, these items contain no digitally-based circuitry, and thus are not proper USB devices at all. This can cause problems with some computers—the USB specification requires that devices connect in a low-power mode (100 mA maximum) and state how much current they need, before switching, with the host's permission, into high-power mode.
Some USB devices draw more power than is permitted by the specification for a single port. This is a common requirement of external hard and optical disc drives and other devices with motors or lamps. Such devices can be used with an external power supply of adequate rating; some external hubs may, in practice, supply sufficient power. For portable devices where external power is not available, but not more than 1 A is required at 5 V, devices may have connectors to allow the use of two USB cables, doubling available power but reducing the number of USB ports available to other devices. Amongst others, a number of peripherals for IBM laptops (now made by Lenovo) are designed to use dual USB connections.
USB-powered devices attempting to draw large currents without requesting the power will not work with certain USB controllers, and will either disrupt other devices on the bus or fail to work themselves (or both). Those problems with the abuse of the USB power supply have inspired a number of April Fool hoaxes, like the introduction of a USB-powered George Foreman Grill and a desktop USB Fondue Set.
WR |
Draft
Intermediate Member
Username: Draft
Post Number: 142
Registered: 7-2006
| | Posted on Saturday, December 09, 2006 - 11:01 am: |
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Thanks for the information, but I use a DC-powered hub (stand-alone, not PC-connected) for the 3 coolers I have running now, 2 of which have been on 24/7 for about 3 months with no issues. And I will be sure to unplug my George Foreman Grill from the USB-hub when I am not using it. =) |
Hotwire
Senior Member
Username: Hotwire
Post Number: 2111
Registered: 1-2005
| | Posted on Saturday, December 09, 2006 - 12:22 pm: |
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 USB powered Foreman Grill!
Terrific idea about the coolers. I wonder this...Suppose I got my hands on one and modified it somehow so that I could wire a multi voltage power supply to it. Just plug it up to my invertor for use in the mobile. Never have seen one so I don't know but my interest is sparked now!
kenny
cef491 |
Draft
Intermediate Member
Username: Draft
Post Number: 143
Registered: 7-2006
| | Posted on Saturday, December 09, 2006 - 4:05 pm: |
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I don't see why that could not be done. I was also thinking of wiring up an old low voltage DC transformer to one of the coolers. I have collected a box of them over the years and I don't think 3VDC would hurt the cooler unit. |
Hotwire
Senior Member
Username: Hotwire
Post Number: 2115
Registered: 1-2005
| | Posted on Sunday, December 10, 2006 - 1:31 pm: |
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No it would not hurt it. I have done stuff like that manny times. I have discovered that on some brushless motor fans if the voltage is not right{to low} they won't even come on until you reach the required voltage and if you reverse polarity you get a puff of smoke!
kenny
cef491 |
Bridge_man
Junior Member
Username: Bridge_man
Post Number: 49
Registered: 3-2006
| | Posted on Monday, December 11, 2006 - 10:12 pm: |
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how about a couple of pics of your cooling system? |
Draft
Intermediate Member
Username: Draft
Post Number: 146
Registered: 7-2006
| | Posted on Tuesday, December 12, 2006 - 4:03 pm: |
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Check out my "Member Pictures" area under DRAFT, you should be able to see a couple of photo's showing the cooling pads under the T/S and the IC-7000. |
