Help Needed : A USB 5V Electric Heater Circuit

After searching much on google i came across this forum, with high hopes of finding some guide to a USB 5V Electric Heater. Any Ideas ?

The USB specification only sources a max of 500 mA per port. You're not going to generate much heat from that. Attempting to draw too much current from the USB port may cause serious damage to your computer. You'll get more heat from the cooling fans than anything you can hook up to the USB port.

I would certainly look for a better source of power than a USB port. A 9V battery might work much better and less risk of damaging your computer.

Good luck.
Michael

yeah true. but the basic idea of a project is to stick to USB lets say i want to make a USB Cup Warmer to maintain my TEA or Coffee temperature... although the requirement is not to dissipate much heat to boil water but just to keep it warm...

Thank You.

Amongst the various laws of physics and electronics, power is the product of voltage and current. Hence, 5 volts at 500 mA will yield just shy of 2.5 watts. My coffee cup warmer draws about 17 watts and just barely keeps my coffee warm. I think you are going to fall a little short of your goal. Granted, light bulbs are not necessarily the best heat source, but good enough for comparison purposes. You will basically be attempting to keep your coffee warm by the heat of one or two miniature Christmas tree light bulbs.

Let us know how that works for you.

hi

just a thought. I known that some external hard drives use 2 usb connectors to i think increase the current that they can draw. maybe an avenue worth investigating.

how about a powered usb hub ?

I can rememebr though that when i try to draw too much from my laptop things just stop working till i unplug the offending device.

After re-reading this old post, I realized you just want to keep a cup of coffee warm. Forget USB. That would be like trying to pull a train with a little R/C truck from Wal-Mart. It just ain't gonna happen.

Instead, just mount one of those swinging wire cup holders for boats on the back of your case, suspending your cup in front of the cooling fan. In most modern PCs, that should exhaust more than enough heat to keep your tea warm.

hmm....wondering ...

i us in my wind generators a 10 ohm 10w sandblock type wire wound resistor. bolted in laying against gear box so the oil doesnt freeze or get so thick blades wont turn up state new york damn cold in the winter. 20 above to 20 below at night.generator 50 feet up in air and cold wind.

ever since tv was invented the problem with power
supplies in early set was these resistor create to much heat espeacilly in summer time. along with other componets.

so with that said use a 10 ohm 5 or 10 watts across your 5v supply of the power supply it will be fine.
its been done be for. since time.

PS: lower the voltage higher the current flow the more heat you get. the easy way to mount use a long screw flat washer each end use nut to tighten washers snug. then a sec nut a few mm from that one. two nuts put on one stick in mounting hole but another nut on backside. plenty of hole to choose from inside cabinet

hobbist tv/appliance repair 42yrs retired also a tranny rebuilder