Externet
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You do need those two 1000 ohms resistors in the circuit.
Miguel
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It should.
Come back with results. Some transistors have the habit of staying on when a 'pull down' resistor is omitted, but go ahead.
Miguel
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A battery powered cooling device can be as simple as a propeller promoting faster evaporation from the towel surface.
A Peltier effect cooling device would also work, if its heating half is also able to cool itself by wind of fan.
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A towel presents a very porous and large surface that promotes its moisture to evaporate faster as there is large area of water contacting the air.
When water evaporates absorbs heat. 540 calories each gram. That cools the wet towel, and you in contact with it.
It is nothing out of the ordinary and well known effect.
When you want to evaporate water, you heat it up with a flame, sun rays,... or your warm neck. If you want the same in turbo mode, wet the towel in alcohol.
http://en.wikipedia.org/wiki/Evaporative_cooler
Miguel
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Hi.
The first schematic is a theoric analogy for the AND gate. The lamp, relay or load would connect between the 'out' node and the ground (bottom)
The positive of your battery goes at the top and its negative to the ground.
The second schematic is very wrong. Erase the short vertical line portion above the top transistor that joins the red and black curved wires.
The leftmost vertical line is very wrong. Puts a direct short circuit connection between the battery terminals. At least erase the portion from the "0V" up to the lower B switch
The bulb won't shine bright as has a 680 ohm resistor in series with it. A led instead of the light bulb would work much better. Observe polarity if you replace it. Anode to the top (+) , cathode to the upper transistor collector.
The top horizontal line is where you connect your 6V battery (+); the bottom horizontal line is for the battery (-) Ignore or erase the rightmost extension of the bottom line, (from the 680 ohm resistor towards the right.)
Miguel
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Thanks, John.
OK, understood that the only heat of vaporization is supplied by the amount of heat the litre of water has at the initial temperature. When it gets 'all used up', water freezes. So I have to supply heat if the initial water temperature does not provide the calories needed.
Is the heat of vaporization constant 540Kcal/litre also under vacuum ?
How do I calculate the amount of heat the 1 litre will yield at a given starting temperature?;
Or; At what initial water temperature should the process begin to have all the water vaporized with no freezing ?
Miguel
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Hi.
Lost in space on how to calculate, or how to make a nomogram/chart; please some guidance.
1 litre of water at 20C in a regulable vacuum chamber, no heat added.
At what amount of vacuum will the litre evaporate in one hour ?
Or, if wanted to evaporate 1 litre in one hour, how much vacuum should be applied ?
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Now, the water can freeze if the vacuum is considerable ( I do not know the figure), so that should be avoided if evaporation is desired, as if frozen, the 'sublimation/evaporation' speed would considerably decrease -Am I wrong there ?
The optimal condition could then be to keep the boiling water from freezing (about not less than 5C) due to vacuum. Am I wrong here ? Is the water freezing at 0 C or at another temperature due to the vacuum ?
How to calculate/chart the amount of vacuum that will evaporate the litre of water faster ?
Will the litre of water evaporate faster under vacuum if its starting temperature is 80C ?
What would be the temperature of the water vapor flowing trough the vacuum pump suction hose ?
The X-Y chart could ideally fit initial water temperature, final water temperature, vacuum amount, time, volume evaporated...
Thanks for light on any or all of the above.
Miguel
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Try fiberglass or carbonfiber reinforced plastic foil. Seen it in thinner than a business card, and can be sanded down further.
Edited: added---> http://www.protechcomposite.com/servlet/the-40/carbon-fiber-sheet-panel/Detail
Miguel
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I think the game's generally called nim and the trick for always winning is based on parity.
Nope, it is not based on parity, there is no trick, as any player can choose the move. It's mathematics.
If anyone wants, we could play a few times right here on the forum. If you want to make it more interesting, we could do a 1 - 3 - 5 - 7 - 9 instead of 1 - 3 - 5 - 7
The simple way ? OK:
I
III
IIIII
IIIIIII
(Just write the next 'matches' pattern on the response)
Miguel
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When light enters a different medium changes its propagation speed, right ?
...does it decelerates or accelerates at that transition ?
When light at c hits a mirror and bounces back at -c, there is an instant when its speed is zero. Is it?
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Impressive work shown live on NASA TV; and I wonder...
All those items, assemblies, tools they are handling, replacing, touching... at what temperature are they ??
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Solid ? ... An iron bar. Red hot is still solid.
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Different approach residing in my 'favorites' for years :
http://www.eskimo.com/~billb/miscon/whatis.html
Miguel
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Just wanted to share what I just saw; when I got the camera the bird was gone.
A hummingbird feeding from spiders that hide under a handrail at my home exterior.
Thought they were strictly vegetarians. At least this one is not.
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Partially agree with the drag, but the question was about counteracting the tilt
Partially, because the huge, huge ballast in a non-catamaran sailboat keel could be then highly reduced, which would decrease draft and consequently drag.
Martin:
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A sailboat tilts considerably with strong wind.
Could a sailboat fitted with an inverted T keel, the horizontal 'wings' capable of independently adjusting pitch, force the hull to stay level ?
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Hi.
Why a diamond needle wears out by playing vinyl records ? What is there in vinyl harder than diamond in order to erode it ?
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If a small, -say 1cc- human brain portion is safely, properly replaced/swapped with same exact lobe/area from another human; would it carry memories/functions/knowledge with it ?
Has it been done ? How good/accurate/reliable is the current surgical technology for something like that ?
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Hi.
A liquid crystal display has indium? transparent traces that make the electric contact to the circuitry and enter the glass sandwich to turn on the segments, and a couple of the traces seem interrupted.
Is there some simple easy-to-find liquid that I can apply with a (nail painting) brush to those traces to restore electrical path, and stay conductive after drying?
Does not need to be transparent, the available silver inks to do the work are more expensive than the item to be repaired, and I would use a 0.01% of the bottle. Not worth it.
Thanks,
Miguel.
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Hi. Thanks; it is getting really hard to put this in the right wording.
It is not about avoiding a gearhead. Such motor would be driving a gearcase. A speed controller would be used too.
It is about decreasing the components ratings and stresses.
A power source, a controller, the wiring and the motor itself are subject to greater stresses when starting to spin a motor under load because the slow commutation speeds and very large currents.
For a given torque need starting under load at -say 0.5 rev/sec- demands a lot of current.
That same given torque need can be achieved with smaller forces (weaker magnetic fields) applied more distant from the shaft
It is not about increasing energy output. Comparatively, it takes less force to manually spin a wheel by turning it as far as possible from the shaft than turning it near the shaft to produce the same torque.
It is about using less force x larger distance from the shaft to achieve the same torque and at the same time getting high tangential speed.
Would that demand less current ?
Trying again :
As a smaller force far from the shaft (large disc shaped motor) can achieve the same torque than a much larger force near the shaft (conventional shape motor);
a weaker magnetic force (smaller windings, current and ampere turns) far from the shaft can achieve the same torque than a much larger force near the shaft (large windings, current and ampere turns)
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How could a permanent magnet electric motor be built/designed for slower rpm turning shaft but with 'normally' high commutation speed (passing of magnets in front of coils) ?
Would a 60cm - 100cm diameter motor just ~5 cm thick -disc shaped motor, with a large number of magnets placed at the peripheria and a corresponding large number of coil poles do it ?
Being the magnetic propulsion forces at a 'large' distance from the shaft with a large tangential speed use less force to produce same high shaft torque ?
It is hard to express in writing, I hope the above is understandable...
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I would venture to say that if the algae and organisms have cells, they will be ruptured by the pass of electric current and die, in seconds.
And the 220VAC live or phase wire, if its other return neutral is grounded, you do not need to submerge both in the pool centre. The phase wire will create the current towards the body of the pool.
The circuit breaker does not need to trip, the current can be easily limited with a light bulb in series:
220VAC--------breaker or fuse--------bulb-----------water---------pool surfaces(Ground)
Obviously any grounded metal attached to the pool surfaces will concentrate the current towards its sorroundings.
I would try. Nothing to lose. No risks of anything if done with common sense and safety precaution. You don't throw a live wire to the pool. You dip them first and then turn on.The highest the wattage of the 220V light bulb, the highest the current forced trough the water. And ions from chemicals in the water, also will increase the current.
If the 220VAC is two phases, floating from ground, you can dip both in the pool ends as you say, with the bulb in series. It won't trip any breaker.
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The proof a camera does not capture souls, is to take more photographs of the same 'now souless' subject from the first picture...
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Solutions that change in color...
in Applied Chemistry
Posted
Hi.
Trying to find out if by mixing a few not-fancy compounds, a thick ink can be made, like the ones used in ballpoint pens.
Remember those high school experiments that produce colored solutions... Can they be made in a viscous form?
How are ballpoint inks made?