Comments on: Beanzawave – the Microwave oven powered by your computer

By: pruefi

pruefi — Wed, 10 Jun 2009 08:55:05 +0000

Assume
P_el(USB)=2.5W
m(meal)=300g
T=50K
c_m=4J/(g*K)
Q(Energie to Heat)=c_m*m*T
Q=6000J
t(time to Heat)=Q/P_el(USB)=400min!!!

By: a non e mous

a non e mous — Tue, 09 Jun 2009 05:54:31 +0000

…litchen….

Obviously, my manual dexterity is somewhat lacking today!

By: a non e mous

a non e mous — Tue, 09 Jun 2009 05:39:02 +0000

typo alert!!!

a standard litchen microwave should be deliver about 1000 watts, not 100…

By: a non e mous

a non e mous — Tue, 09 Jun 2009 05:37:14 +0000

Hold on a minute….

Watts = volts x amps

In Australia, power is delivered to a standard power point at 240 volts, typically rated to 10 amps for a standard household power circuit. That’s a potential of 2400 watts available on that circuit.

These days a typical kitchen microwave has a power ouput of 100 watts or more, and will take almost two minutes to boil a cup of cold water.

A typical USB port will output = 5 volts at 500 milliamps (half of one amp). Therefore 5v x 500ma = 2.5 watts.

Assuming that a device might take multiple USB outputs to get more power, that is still going to be limited by the number of ports available. My brand new desktop computer has 8 ports, hence a total of 20 watts.

Even if one has that many ports, it’s still barely enough to maintain a temperature, let alone heat something from stone cold.