Man powers up PC to pop popcorn
Hot Butter revival?
Video Given the number of film fanatics who watch movies on their laptops, popcorn by your PC is probably just what the doctor ordered. One DIY hardware pioneer has worked out how to make your very own USB-powered popcorn maker.
All it takes is a baked bean tin, a jar, an old USB cable, a high-intensity light bulb, and some thermal paste.
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Oh, and some salt and corn kernels, of course.
... If you add butter and salt, it tastes like... well, salty butter...
By my calculations.
If we assume that we want to heat 10g of popcorn to 150C , then by my calculations:
Using Specific Heat Capacity:
q = mct
c = 4200, t = 130, m = 0.01
q = 4200 * 130 * 0.01 = 5460 J
Now Power is Joules per Second:
p = q / t
p = 2.5 , q = 5460
Therefore in order to raise the temperature of 10g of pop corn to 150C at maximum USB power it would take:
5460 / 2.5 = t = 2,184 Seconds = 36 Minutes
This assumes that heat transfer is 100% efficient and there is no heat loss.
Now providing that the heat input into the system is greater than the heat loss, there should eventually
be some popcorn.
I think the more interesting question is how long it took.
Another thing to note, is that the USB bus does not provide 500mA of power unless requested by the device.
Therefore it is likely in this situation the USB bus is only providing 100mA, IE 0.5W
But that is just my views.
...slow news day then, yeah?
Actually there were clearly two bulbs in series...
...which would work pretty well off 5 volts.
Power consumption would be in the region of 1.5 watts.
- 100% efficiency on power transfer to heat within the can
- the system was isolated and within a vacuum
- specific heat capacity of steel as 500 J/kg C
- steel can mass of 100 grammes
by my calculation it would take about an hour and a quarter to increase the temperature of the can by 130 degrees C from a nominal room temperature of 20 degrees C.
In reality the system would reach equilibrium at much lower than that, although there may be localised points at the base of the can that reach the temperature required to pop one or two kernels.
Mines the white one with the pen protector..
Jebus, did I watch a different video?
The 2 bulbs were sealed into a jar cap that was in turn glued onto the bottom of the tin can, the majority of the heat generated by the bulbs would be trapped and transfer through the bottom of the can where gravity holds corn kernels against the hot parts with oil added for better heat transfer.
The whole can doesn't have to hit 150C and the 'Thermal grease' is on the outside of the can and so doesn't come into contact with the popcorn.
I note an insulator/reflector added to the jar cap, the fact that we can clearly see corn popping before he puts the jar over the top (and while in place), and that on pouring out the popcorn the base of the can shows heat discolouration. Looks like he shockingly cut out ten minutes of cooking time, which is a shame as that would have put this short film right up there with the You Tube classics "my kettle boiling" and "paint drying on sunny day"
Not Fake but I doubt those bulbs would operate for very long making for some expensive pop corn regardless*
*and yet still cheaper than you can buy it at the cinema.