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A LED proper connection to two cells in series should include a resistor also in series to limit the current. Lacking current limitation, the thermal properties of the LED can increase the current demand as the LED warms up with elapsed time on. The batteries can also change their internal resistance with temperature with the elapsed time on. As the cells deplete, the current should decrease as the battery voltage gets lower in time. The time can be many hours, depending on the capability and charge state of the battery. Unequal state of charge for each cell can also cause unusual readings.

Hi. Use a chart for sun position at your coordinates. It tells you at what exact sidereal time/date, sun azimuth is at 180 degrees. Hope for sunny sky. I did it to orient a satellite dish antenna and worked very well. ----> https://aa.usno.navy.mil/data/docs/AltAz.php There is other charts/calculators to choose.

Check if this older thread contributes with some extra information: ---->

Consider there is PTC -positive temperature coefficient- and NTC -negative temperature coefficient- devices/probes

Is it improper to add temperature and 'verticality' (balance) senses to the normally listed hearing, tact, taste, vision, smell ? An eighth could be the common sense, the least common of senses... I can directionally detect nearby hot spots with cheeks, hot/cold ingested foods; body position in darkness/bed, by inner ear or guts.

The engine acts as a compressor with blocked inlet/outlet. And it is engine braking, not breaking... Edited- added ----> https://en.wikipedia.org/wiki/Engine_braking

Many years ago, ocean liners dumped their own refuse to sea. Later, was legislated for international waters only. Years later, all ships must bring to ports their garbage. U.S. has its legislation ----> https://www.gc.noaa.gov/documents/gcil_crs_oda.pdf Go to 'Laws and treaties' at ----> https://en.wikipedia.org/wiki/Marine_debris

Hi. These gadgets for reading pH; how they read on same soil samples with different contents of moisture ? Is there any compensating to ignore changes of conductivity by soil wetness ? How dry or wet can soil be for accurate reading ?

The airplane works on 'electric wind' from ion emission. The radiometer is onto something else.

What if these spinning arms were instead, propeller blades for that airplane ? Would it work better ?

The report does not specify, or I missed it. Now available ----> https://www3.nhk.or.jp/nhkworld/en/vod/scienceview/2015204/ Time stamp ~4:00

Is it correct to name it "solid state" flight/propulsion as by time stamp ~3:00 ?

Update; it is available now. All the program is enjoyable, but the subject surfaces by time stamp ~4:00 if preferred to go direct. ----> https://www3.nhk.or.jp/nhkworld/en/vod/scienceview/2015204/

Or mind boggling. Compared to the already surprising satellite highest resolution photography, focusing from such distance to a tiny spot shows how advanced techniques that are kept from general public knowledge may exist. If such has a civil application, military uses could map a relief of the grains of sand on a beach from such distance.

Saw a report in television that japanese are measuring structural level irregularities in aging bridges with resolution of one milimetre from a satellite using its synthetic aperture radar. Wondering if I was half asleep during the report; I had to see it again. I was not asleep. That is their spectacular unbelievable claim. The program should be available as video-on-demand soon. ----> https://www3.nhk.or.jp/nhkworld/en/tv/scienceview/20181121/2015204/

Thanks. That is good logic for fire-prone structures built with papered gypsum and sticks as in U.S.A. Not the same for other construction materials, other building codes.

Hi. Is there a replacement for typical metal HVAC ducting in CPVC, PVC, FRP, other rigid plastics, in 15cm(6") to 30cm(12") ? Something with smooth inside surface, to be insulated on its outside ? Perhaps ~1mm wall with available elbows, tees, connectors available ? -Not flexible 'hose'- What is 'schedule' 5, 10 ?

Or cold, if you prefer. ----> https://www.google.com/search?q=icesense3&client=ubuntu&hs=6ey&channel=fs&source=lnms&tbm=vid&sa=X&ved=0ahUKEwixjvOI95feAhVkqlkKHTz8C1IQ_AUIECgD&biw=1366&bih=549

Looking at the subject from an engineering point of view, as posts comment on the use of waste plastic as road construction material additive... Any plastics expert that can confirm if this is possible ? : Melting mixed types of thermoplastic as collected, at a temperature that all become fluid in a cotton sugar type of machine to create fractional mm fibers to mix with concrete, asphalt, even soil ? (No need to painfully classify types of plastic ) (Do not know if such is the process to make pillow fillings and alike) Would provide a 'rebar' type of reinforcing. -If this post should be moved to engineering, please let me know to open a proper thread-

Thanks. Adding magnetic material would destroy the compass ability to aim properly, if I understand you.

It has to move with the compass dial as one piece, shifted in heading.

Thanks. Nothing wrong with the markings on the compass dial, just need an extra shiftable disk on top, like on the last picture. Perhaps I should look for a dry compass with openable cover, shift the added disc and close lid.

Thanks. No, but I prefer to 2D print such protractor markings on a transparency film as for 'overhead' projectors. Cutting teeth is a good idea, a manual setting/rotating knob is preferred. What are these ? Anyone knows ?

Hi all. Headache is possible. Am after ways to attach a properly sized plastic disc like this on top of the flatty portion of a marine compass dial : And being capable of adjusting its bearing in respect of the compass bearing. Yes, disasembling the compass, install it, and reassemble once. The hard part is the added 360o ruler disc (how is it called?) should be positionable from the outside. As when the compass indicates a -say 50 degree heading- the added disc to indicate a chosen shift -say aiming a 230o heading- Perhaps some perforation or method for halting the compass, and a knob? for the disc as way to turn the (friction? mounted) disc respect to it could be in your skills ? It is likely a sealed dome, filled with fluid.

I would say the magnetic field will be contained and follow the mu-metal path with minimal field outside it. Your sketch should define/identify the colored sections to better understand you.