A challenge

There will be Brownie points awarded to anyone who can demonstrate the boiling of a drop of wine using 5 volts.

Gareth.

Reply to
Gareth Magennis
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put that drop of wine on remnants of solder flux. It's likely more than 5V. Do I get ice cream with my brownie?

Reply to
mike

Sure. Take a typical PCB trace that's about 4" long. My guess(tm), that's about 0.1 ohms. The available current at 5V can be at least 3 time the charger current since the internal switching regulator steps the 19V down to 5V. I'll guess a conservative 6 amps. The voltage doesn't matter. Power = I^2 * R = 6^2 * 0.1 = 3.6 watts That will burn your finger and melt the plastic. If you don't believe me, find a small 1/2 watt resistor, attach to a power supply so that it dissipated a few watts, and notice that it will burn your finger nicely after a few seconds. It may take a while to boil a few drops of water but it eventually will do so.

Let's grind the numbers.

1 ounce of water = 28.35 grams To raise the water temperature to boiling point, you will need:

Calories = Mass * (Tboil - Troom) = 28.35 grams * (100C - 25C) = 2120 calories

To turn this into steam: Steam = Mass * calories = 28.35 * 540 = 15300 calories

Total energy needed to steam 1 oz of water: Total = Heat + Steam = 2120 + 15300 = 17420 calories

1 KW-hr = 860424 calories: Calories = 17420 / 860424 = 20.2 W-hrs

If your heater can generate about 3 watts, it will take: Time to boil 1 oz of water = 20.2 Watt-hrs / 3 Watts = 7 hrs

Less than an oz of water will take proportionally less. There are roughly 250 drops of water in an ounce of water (using the drippy faucet model). Therefore, one drop of water will take: Time to boil 1 drop with 3 watts = 7 hrs / 250 = 1.7 minutes

Please ship the brownies to the address below.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Get a 5 volt shutter, sun, magnifying glass....

Greg

Reply to
gregz

Hold on. While that is admirable psychomath, you have made a mistake.

The 0.1 ohms is not what it is working into. That would be the resistance o f the wine itself. The liquid, somewhat like ethylene glocol in a projectio n TV should have a negative resistance curve as plotted against time when v oltage is applied.

While your calculations are in order so far other than that, we need to kno w how long it took for the pop pop fizz fizz to happen after the spill.

The other possible error that needs to be considered is that the line in qu estion uses three or four pins of the connector. Granted the 5 V or whateve r might pull some current, But the backlight would pull more, at least in w attage. The higher voltage would accelerate the decline of resistance over time. (how do you make the delta sign on a webpage anyway ?)

This could be in error but I think not, the 19 V from the PS is not used di rectly in the laptop. My batteries say 11.1 V, it is logical to assume that the voltage is preregulated down to at least that for internal use, in fac t lower for when it becomes partially discharged.

Also I see no inductor near that ex-regulator on the board so it is logical to assume it is linear. A little SMD like that cannot dissipate much so th ere is no way it was dropping more than a volt or two even at less than an amp. Also, being linear it cannot put out more current than it draws.

With an 11.1 volt batttery, I would guess that it runs on 9 V internally. A lso the lack of an inductor seems to indicate that the chief function of th e IC is to turn the inverter on and off. It could be used to dim it but bei ng linear, I tend to doubt it. However the is a reason they didn't just use a transistor, unless they were getting switchable regulators cheaper. I'm sure that happens sometimes.

I think you're damn close, but it needs just a bit of tweaking. I strongly beieve the sequence of events led to the melting plastic which gave up it's carbon. The IC was fine up until the current got too high. Most likely the mixture of stuff in the wine and the plastic was the most conductive. Perh aps it flickered but in the OP's inebriated state he did not notice.

In any case, if I were the owner of the thing I would consider trying to se ll the display and use it with a monitor, or perhaps buy one with a broken screen and change it, then pop in his HD and be good to go.

In any case, I think we need to know the time period between the spill and when the smoke escaped to derive an accurate figure.

You know folks have to be careful when offering up brownies :

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Reply to
jurb6006

I beg to differ. I don't make mistrakes.

the wine itself. The liquid, somewhat like ethylene glocol in a projection TV should have a negative resistance curve as plotted against time when voltage is applied.

Please re-read the challenge. "There will be Brownie points awarded to anyone who can demonstrate the boiling of a drop of wine using 5 volts." Nowhere does it require that the current has to go through the wine.

Note that my theory doesn't completely hold water (or wine). The explosion of two nearby parts suggests that they may be connected in some manner, perhaps by a wire. However, that's only part of the problem. Even if I could boil wine with a hot wire, the temperature necessary to carbonize a 6 pin SOT device is much higher than boiling wine. Same with melting plastic. Boiling wine just isn't hot enough. It also begs the question of "where's the wire" which would presumably be either fused, smoked, or vaporized by the excess current. However, none of that shows in the photos. My guess(tm) is that it's on the other side of the motherboard. However, there would not be any wine puddle on that side. More evidence please.

The neighbors kid just arrived bearing most of the things he's borrowed in the last year or so. I think he might want something. Gotta run. More guesswork later.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Soldering gun

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Boris
Reply to
Boris Mohar

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