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    Today I learned

    That sounds vaguely familiar, which made me look it up... And to the rescue: https://www.khanacademy.org/science/biology/membranes-and-transport/diffusion-and-osmosis/a/osmosis In this case, meaning a solution that has the same osmotic pressure of solute as the solution within a cell does. Don't...
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    Today I learned

    That's the effect of Diatomaceous Earth (although I've found it not very effective for many bugs), could be a secondary effect of Boric Acid too. The reports I've been able to find on .GOV sites state the main route is when the cockroaches groom they eat the Boric Acid, which is poisonous. I...
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    Today I learned

    Many many todays ago I learned that Boric Acid (H3BO3) powder is extraordinarily effective against insects... it even kills off cockroaches! It's also less harsh to us Humans than the manufactured insecticides. Some people here in the US have found it to work when sprinkled around before laying...
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    Door mechanical stopper

    Don't know about the 'common', where I live the measured interior knob height is 35½-36 in. and the exterior is 39½.
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    Door mechanical stopper

    Th closer to vertical the bar is set, the less likely it is to slip... up to a point. If actually vertical it won't be of much use at all. The optimum angle depends on the coefficient of friction between the floor and the material of the foot of the bar. Polished concrete and tile floors are the...
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    Need suggestions for a new camera

    The A560 Date and Time uses a separate battery, a CR1220. See page 106 of the Advanced User Guide: http://gdlp01.c-wss.com/gds/2/0900001212/01/PSA560CUGad_ENg.pdf Cheers, Tom
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    Door mechanical stopper

    You mention that the door frame is just light-weight wood set into a hole in the concrete wall. You want to secure the door with better locks. With that construction, you have the same problem with the hinges breaking out the door frame. Also, if you floor-mount a stop/lock as in posts #12 or...
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    9V 0.5A battery pack

    Hmm... I always thought voltage regulators regulated voltage. If they keep current constant, say at 100mA for instance, wouldn't a 10,000Ω load resistor have 1,000 Volts across it? Rather impressive for a 9V supply.
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    Resistivity equation relating to equations for resistors

    Correct. However your first post has this: If there are two parallel resistors, say 1Ω and 2Ω, that formula says R total = 1/1 + 1/2 R total = 1+½ R total = 1½Ω, which is an increase in value. That's why I suggested you might want to review the situation. Cheers, Tom
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    Resistivity equation relating to equations for resistors

    Uhmm... you might want to review that for future reference. When more resistors are added in parallel does RTOTAL increase or decrease? Cheers, Tom
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    Easy tool to see a cross section?

    I don't have the program and the site documentation is sparse. They also have a pay version of the program (about which I also know nothing), that may have documentation. If the program can do slices in arbitrary planes, that would be the simplest. Can the program do intersections of objects...
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    Easy tool to see a cross section?

    Well, not me... But here is a 3D drawing/editing/viewing program I just stumbled across that happens to be free... it's even from an established supplier. https://www.nchsoftware.com/meshmagic3d/index.html Cheers, Tom p.s. Sorry about my earlier post #4, I mis-interpreted your requirements!
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    Easy tool to see a cross section?

    https://www.google.com/search?&q=how+to+draw+ellipse https://www.google.com/search?I&q=draw+ellipse+online https://www.google.com/search?&q=how+to+draw+an+ellipse+with+a+compass Pick an approach, draw/plot it, measure it. Sure beats trying to calculate it! Cheers, Tom
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    Using electrical appliances brought from another country

    If it is just a resistance heater you can use it on any voltage at or below its design voltage. For instance here in the US the typical wall outlet has 120Volts. A 120V rated heater will work fine, whereas a 240V heater will have a quarter to half the heat output. For heaters with a fan motor...
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    Where do I put this Server Room's air exhaust?

    Servers you need to keep cool and clean. Just circulating outside air will keep them cool part of the time (depending on climate), keeping them clean is more difficult. Maintaining a few computers in the near-suburbs I had to remove the motherboards and graphics cards about every five years...
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    Proper barograph linkage settings for maximum pen displacement?

    Maybe you can figure out a way to get you and the two barometers closer to a weather station while also accessing their reported pressure. Even if you do not have portable Internet access, a cell phone to someone with Internet access could work. Another possibility is if the history of the...
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    Proper barograph linkage settings for maximum pen displacement?

    Referring to the top-view photo in post #11, try placing a coin on top of the assembly that is on top of the aneroid capsule, the piece that the horizontal bar is attached to. I have no idea how much weight will actually be needed, the idea is enough weight to move the pen a recognizable...
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    Stargazing Solar imaging and techniques

    Replaced with "Don't Die of Boredom" 'work'. :oldwink:
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    Misc. Mechanism or method to unlock a window from the outside?

    Once the mechanics are figured out, the communication could be done with: A garage door remote control and receiver. These use a radio link and don't need line-of-site Even cheaper, a toy remote control car (boat, airplane) from the toy store (or on-line) A TV remote, but finding a receiver...
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    Proper barograph linkage settings for maximum pen displacement?

    I think you mis-interpreted the suggestion. What both he and I suggested, it not quite the same words, was to use the adjustment screw to get the vertical linkage moved horizontally closer to the axle. Please try to undo the most recent change. Then use the Adjustment Screw to get the pen...
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    Unable to get the desired impedance in this LTspice simulation

    The article is stating that to match 52Ω to 2000Ω you will need a an inductive reactance of 318Ω and a capacitive reactance of 328Ω. You choose the parts values, inductance and capacitance, to get those reactances at whatever frequency you are operating at. If you want to operate at a different...
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    Proper barograph linkage settings for maximum pen displacement?

    Well that's a bit unclear. Are you saying that: After a change in barometric pressure and then a return to the original value, that the pen does not return to the same reading? A pressure higher than nominal, followed by a pressure lower than nominal by the same amount, gives different...
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    Proper barograph linkage settings for maximum pen displacement?

    Ahh! More information. First, Taylor is still in business but no longer shows a barograph as a product. You could try an email, including a photo, asking if there is ANY useage or calibration information available. http://taylor-enviro.com/taylor-support/ If you get the run-around from them...
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    How to design a slide switch mechanism to be waterproof -- ideas?

    These folks enclose the slide handle in a polymer boot. https://www.e-switch.com/product-catalog/sealed/product-lines/500r-series-slide-switch-sealed-to-ip67 above found with: https://www.google.com/search?&q=%2Bwaterproof+%2Bslide+%2Bswitch (that's putting {+waterproof +slide +switch} in the...
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    Anybody having trouble w/ Windows Explorer search?

    I gave up on the Microsoft search/indexing about a decade ago, mainly because the indexing was bogging down disk accesses. Been using something called Agent Ransack which doesn't use an index, still pretty quick though. It is a free/light version of a full-blown, with indexing, search utility...
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    Is this mist or haze?

    The reason for that sharp demarcation in the photo of post 17 is an Inversion Layer. That's when there is a layer of cooler air above that traps the warmer air near the ground. Quite common here in the Southern California Summer. The warmer ground air is attributed to the City Effect, where all...
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    Proper barograph linkage settings for maximum pen displacement?

    That is not necessary. My suggestions were based on the first photos you posted which did not clearly show the adjustment screw for the link. What is needed is to thread the adjustment screw further in to the axle to increase the pen travel. Look at it this way: For a given barometric...
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    I Sodium Vapor Lamps (low pressure) for spectral calibration and diffraction work

    Try looking here: https://www.newport.com/medias/sys_master/images/images/h55/hfd/8797293281310/Typical-Spectra-of-Spectral-Calib-Lamps.pdf above found with: https://www.google.com/search?&q=neon+lamp+spectral+lines
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    Most common computer interface errors

    TRYING to use (or not trigger) a touch screen on a tablet or phone!
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    Dumb Hypothetical Question -- Is it Ever "Profitable" to be Uninsured (Health)?

    Yup, worked for me. Even with a couple long-term situations. However the meds were available as generics, and when my income was down I had ALOT of paperwork to get free meds from the manufacturers. I was lucky though, worst Emergency Room visit was a motorcycle accident with just some scraped...
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