Multiplexor, a quick hand warmer is a 2 ohm / 3 watt resistor and a D battery. That will keep your hand warm for about 5 minutes. Then you can toss the battery.
Just use Ohms law and remember, wattage is heat.
Later
Bruce
Just use Ohms law and remember, wattage is heat.
Later
Bruce
HDTVman said:Multiplexor, a quick hand warmer is a 2 ohm / 3 watt resistor and a D battery. That will keep your hand warm for about 5 minutes. Then you can toss the battery.
Just use Ohms law and remember, wattage is heat.
Later
Bruce
hmm cool ;-) never thought of that... 😀
thanks
Low voltage peltier cooler 6/12 volt one side gets hot the other gets cold. If they fail for your experiments use them on an overclocked PC or something 😉 (Princess Auto has them for prety cheap)
zardoz
zardoz
On a simmilar note, I've got a electric blanket and my girlfriend needs to go wintercamping with school, so I've got to get this running off of a battery (doesn't matter if it doesn't last long, every bit counts). I'd like to run it off a few 12v batteries (maybe three or four to get higher voltages if needed). Any idea on the best way to do it?
JoeBob, how about an inverter? Get one that will just handle the wattage requirements of powering the Electric blanket. Those small inverters are most efficient when running near maximun output. Read the specs. for the inverter and figure out the current usage and size the battery for the amout of time required.
140 watt inverter = 13amps @ 12 volts
13amps for 1 hour = 13amp/hour battery
26amp/hour = 2 hours usage
100 amp hour battery = almost 8 hours usage if the battey is kept warm. At cold temps. the output of the battery will be less.
I would use a deep cycle type battery for this kind of job and charge it as soon as possible or it will fail.
Just an idea.
Later
Bruce
140 watt inverter = 13amps @ 12 volts
13amps for 1 hour = 13amp/hour battery
26amp/hour = 2 hours usage
100 amp hour battery = almost 8 hours usage if the battey is kept warm. At cold temps. the output of the battery will be less.
I would use a deep cycle type battery for this kind of job and charge it as soon as possible or it will fail.
Just an idea.
Later
Bruce
Catalytic heaters
Electricity is precious, difficult to store, and should never be used for heating. After all, all inefficient processes ultimately dissipate their wasted energy as heat. I believe that camping shops sell hand warmers that work by a chemical reaction, or you can store heat very effectively in water because of its humungous specific heat capacity (hot water bottles).
Bikers need electrically heated gloves and boots. After you have ridden 170 miles in the winter on an unfaired bike, you have a new understanding of the word "cold."
Incidentally, Multiplexor, if you ever play cards (bridge, canasta etc) you may prefer my aphorism, "Never underestimate the incompetence of the opposition."
Electricity is precious, difficult to store, and should never be used for heating. After all, all inefficient processes ultimately dissipate their wasted energy as heat. I believe that camping shops sell hand warmers that work by a chemical reaction, or you can store heat very effectively in water because of its humungous specific heat capacity (hot water bottles).
Bikers need electrically heated gloves and boots. After you have ridden 170 miles in the winter on an unfaired bike, you have a new understanding of the word "cold."
Incidentally, Multiplexor, if you ever play cards (bridge, canasta etc) you may prefer my aphorism, "Never underestimate the incompetence of the opposition."
I think we only feel cold because our body temperature is warmer than the surrounding environment. I think that instead of constantly trying to modify the environment by heating it and cooling it we should find a way to regulate our metabolism so that when it is cold outside, we can slow down our metabolism and lower our body temperatures.
Think of how much less energy we would consume!
MR
Think of how much less energy we would consume!
MR
MRehorst said:
I saw a documentary on a dinosaur about that.
Did you ever see a picture of a dinosaur with a great big sail on it's back? Well, the thing was far too squat and heavy to fly. Ever wonder what the sail was for?
It was a solar heating device.
Dinosaurs were colder blooded than mammals. When the temperature went down at night, the dinosaurs' metabolism went down with it, rendering them sluggish and unable to move with any speed.
When morning came, the sun took time to warm the earth and the dinosaurs. However, the dinos with the sail on the back caught more of the sun's warming rays, and were therefore able to move quickly in the morning while their prey were still cold, slow, and sluggish.
Free breakfast for the sail-backs.
I think M. Rehorst is really onto something here.
Let's all Go Jurassic!! 😀 😀
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