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Domestic water purifying depends on the contaminants. If bacteria, virus, microorganisms are the ones to get rid of, several steps are convenient, as filtering, boiling, and ultraviolet, being the most important action of all, to discard the filter as soon as possible, immediately after done with the batch. Filters are very dangerous stuff. For minerals, filtering and reverse osmosis should work. For both, i would go with distillation and chlorination. Miguel

The main misconception and misunderstanding of magnetic interaction is caused by the asumption above ...." What happens to the formula, when the distance is Zero?"... The distance is never zero Because the poles are not points in the magnets; the pole are zones within the magnets. And they are inside, never at the ends, usually spaced at ~4/5 of the lenght of the magnet. Attempting to make a void in the zone of the poles, as to reduce the distance, does not work. The poles partially re-locate around the void. Otherwise, the distance between two magnet poles, if somehow became zero, the force of attraction/repulsion would be infinite. Miguel

Seems so far it will have to be as Tater says, ..."baking soda and powdered citric acid"... Ascorbic acid is the same, right ? Miguel

Hi. Is there any reaction or chain of reactions to obtain any alcohol (propanol, isopropyl, metanol, butanol ...) from calcium carbonate ? Miguel

"...The hydroplane moves forward and rises in the water then the rider pushes down again..." Cannot comprehend how a rigid narrow fin can propel anything upwards when pushed downwards, and from observing the motion, the thing rises at the 'upward' stroke, -not as you say- without having flotation. The forward speed has to be the one creating the force pushing up under the wing, as on an airplane. Without forward motion, it just sinks no matter how much jumping on it. Guessing, the downstroke only provides forward speed somehow, and later in the cycle the forward speed pushes the underside of the wing back up. To happen, the angle of the fin should be changing from 'leading edge down' at the beginning of downstroke and changing to 'leading edge up' to lift at the end of the downstroke... That, I can visualize. For that, the 'wing' should be horizontal at about half submersion. Better said still guessing, the first half of the downstroke provides forward motion, the second half starts providing lift. Now the front canard is pivoted, its angle appears to barely change; going 'leading edge up'? when downstroking. There is some key cadence to keep it going, and calibrated elastics. What would be the effect of a wider wing? Perhaps would not synchronize to the natural human cadence (resonate to jumping) of ~1.5Hz ??? What is the energetic calculation to keep a ~60Kg human above surface, plus propel forward at >1m/s, against drag during for a couple of minutes ? That is the sum of vectors up and forward. Still lost in space... Miguel

There is several versions of the contraption; here is one: http://www.instructables.com/id/EW28Z3LF18DW901/ http://www.instructables.com/id/EW28Z3LF18DW901/?ALLSTEPS And youtube shows these: Miguel

Hello. This contraption keeps its flotation and its forward motion from the operator's movement; what mechanical actions and reactions are involved, and how does each element performs ? Miguel

Hi. That is why chargers that plug in to the cigar lighter exist. Use one hooked to the battery observing proper polarity and you are done. Miguel

It works ! Solar cells and Li-ion battery; precise timing source, dividing/counting logic board, stepper driver board and the mechanism. The black aluminium massive base on the mechanism provides a solid, ball bearing mount for the vertical shaft. The worm screw on the motor shaft steps once every minute, changes direction at 06:00 am and at at 06:000pm. The rotating table support for the mirror (shows a tiny mirror on the picture) Needs cosmetics and arranging all the electronics, inside the black base there is room for them. Miguel

Just panning... for now. Would love to implement a pure mechanical ratcheting for tilt, but suspect it will end with another stepper moving a cam once a month for that. Miguel

Disagree. Light dependent resistors won't work when cloudy even with lenses, losing tracking. If gets cloudy by 3pm, photocells would not see the next sun at dawn to re-aim. A DC motor will not provide a defined exact angle of advance by its wear, thermal and frictional variations. Yes, stepping has its hurdles too. The one I have to solve is to shut it off between steps while remembering which windings to be energized on the next step. Have it running for 48 hours now, pictures to come soon. Miguel

Fully self contained unnatended heliostat. Need to add/post other modules later. Miguel

Project tracker text incomplete, edit ---> add here. "Manage Attachments"

Right, John. Concrete pH is 11 - 12 , very alkaline. And sodium bicarbonate needs an acid to bubble. So it may not work. Damn! -Back to the thinking hat. Miguel

Get a broken sixties or seventies Volkswagen buggy engine block from the wreckyard or a VW shop. They may even pay you to get rid of ! It's nearly pure Magnesium. Actual composition is somewhere on the web, I saw it a long time ago, along with sites about the long pyrotechnics shows done using those engine blocks Miguel Edited: added----> Cannot find now the site that lists the precise alloys per year of VW engine blocks, but it is something very near to 97% Mg. The burning is scrolling down to Mg here: http://www.tb3.com/pyro/

Thanks, fellows, good clues. Borax solution or used transmission fluid (highly penetrant) should then work. Miguel

What chemicals commonly found in households could be used to spray some lumber with, in order to ensure a nasty dinner to insects and protect the wood ? Ammonia, vinegar, kerosene, shaving cream, motor oil, plumbing flushers, chlorine, salt, ..... which should work better and longer ¿? Somehow I believe commercial insecticides work only for a short time, to keep the public buying again and again. Seen a darker colored wood in older houses, that is never touched by termites. What was used to treat them over 60 years ago ? Miguel

From data found on the web, the water molecule diameter is 280 pm; the chlorine ion is 184 pm; the sodium ion is 102 pm. If the water molecule is bigger, how can an osmotic membrane work to filter seawater ions out in desalination? Miguel

Hi all. A given osmotic membrane operates at say-500 psi differential to let the solvent-only pass to the atmospheric side discharge. If the atmospheric discharge side is made to operate in partial vacuum and the solution inlet at atmospheric pressure instead; how to calculate an equivalent condition to equally operate the osmotic membrane? How many mm HG would be an equivalent differential ? Miguel

Perhaps you would have a chance of a response if you at least respected your own language. Miguel

Hi. The battery bank of around 58 V has a 12 Ampere capable charger but that does NOT mean it's meant to work at its full rate; probably less than half that, and after a mains failure. The 80 Amperes hour battery bank can supply telephones for a small town. The 12 V backup power you want to use cannot be for a telephone system. Telephones work with ~50 Volts. Then, I assume the backup system you want to implement is to supply 115VAC for computers or whatever else but not telephony. Those 640 Amperes hour in 8 batteries paralleled to 12 Volts are to supply how many watts of 115VAC? That is neccessary to know. If your answer is say, 240 Watts You need an inverter capable of around 500 Watts continuos duty. The battery charger has to be an 12V automotive type. Its Amperage capability is to be calculated by the time you expect to need to charge the batteries after a power failure. Modyfying the existing 58V charger would need to parallel secondaries of the transformer (if there are taps on it, which I doubt) and add rectification and regulation capability (major surgery) In other words, you may not be able to use the telephony charger, and you have to buy an inverter capable of supplying the computers power needs and powered by 12V if you insist in paralleling them. ---->Look for a continuos duty inverter (or UPS) that uses FOUR 12V batteries in series for nominal 48 V DC input AND capable of supplying the power demands of your computers and then you are done, reusing the same telephony charger. Thinking on using a 12V input inverter is shortsighted, I do not think they exist for large powered outputs. Find a 48V input inverter and you can use the existing charger and batteries, BUT in series. And do not exceed 56 Volts during charge. If it is not an inverter but a UPS, it will have a charger circuit built-in anyway. Miguel

Somewhere I once read that the most nutritive food of all is yams, seconded by nuts. Miguel

Actually, about 75 % of America uses the metric system. United States is the only country that does not. The beer bottle size is just 12 ounces to promote repeated sales as drinking only one or two of those children size beer bottles are never enough. (multiple wallet squeezes) Want a grown up size beer? Get a litre. Miguel

You will have to phrase your explanation properly. And we do not need to guess whatever your APC means. Make it clear and will be able to help. Miguel

Thanks. The cleanliness and transparency is what attracts me, for using such clear gel in glass containers for indoor plants instead of dirt. If such gel can support life in plain mature plants in my living room. But it's better a healthy nice plant on dirt than a dead one in a pretty pot. Miguel