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    COVID-19

    Report similar (Wgtn): neither Pfizer shot gave me any reaction at all. Wife (also hospital, nurse) complained of a sore arm for several days, but seemingly Pfizer seems a workable option. One advantage of not doing anything that anyone understands: no "on call." Still waiting for those numbers...
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    Lora network without Lora Gateway.

    What software, firmware, hardware are you using? Google lora p2p? hits include https://www.seeedstudio.com/blog/2021/04/26/what-is-peer-to-peer-p2p-lora-communication/
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    Single Led flasher circuit.

    Various 555 timer versions will run at those voltages. (google 555 led flasher?) . Also an old favourite UJT. (Google ujt led flasher) . Google it?
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    Can this be repaired by a complete novice please? Basic circuit repair?

    All the electronic parts are replaceable. The circuit board itself seems to have suffered, so that is more difficult. . Repair from this state would take a bit of work, which might be difficult to explain, remotely. Is replacement an option? Does this have a brand or model on it somewhere? The...
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    Newby signing in

    Welcome. Ladder logic still exists and has it's place.
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    Curious guys

    A shiny battery? How do you mean?
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    Possible?

    How is it powered? If you search under solar lights you will find lots of circuits similar to those used in cheap garden LED systems. Generally they work by when the voltage on the battery exceeds that frm the solar cell, they light. When the solar cell exceeds the batery, they light. . Could...
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    "Medical" watch with SOS function without phone. About 10-20m range (2-3 concrete walls)

    I looked at two things about a year ago that might be of interest. One was an alert system for a lone worker in a basement tunnel area. They preferred out by cellular so that it could have multiple numbers to call if one failed.There were multiple offerings here with low-power wristband +...
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    Can't end thread with "Warmest Regards" - i's treated as spam..

    Try "Regards" But not sure such is needed for posts here. Thanks, in advance.
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    VARIAC? With valves!

    The Claude Lyons Group was founded in 1918 .... Might be right :) Search on their site for the part number did not return any hits.
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    Does anybody here do photonics/optoelectronics?

    Are you coming from engineering or physics? Are you contemplating engineering or physics? The source of the lectures you found will likely determine the slant of the lectures. There will be a variety. . I chatted for a time with a Chinese guy who was finishing his PhD in new LEDs. Seemed a...
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    Coilgun back-emf trouble

    Maybe look for the site guidelines. From memory projectile weapons might not fit with this site.
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    converting a high amperage battery to lower amps without reducing voltage on a DC motor.

    frame? shakeboard? buckets? . I really can't tell what you are wanting to do. Do you want to control the speed of something? . For DC motors on DC power supply, eg battery or regulated DC power supply. The short answer for a motor on a battery, or fixed voltage supply, is that the motor will...
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    converting a high amperage battery to lower amps without reducing voltage on a DC motor.

    Give some details of the battery and motor wyou want to use and a few more facts about what you are planning. . The short answer is "It doesn't work like that". (Depending on the motor and what you want to do. . So, if you'd like to give some details, someone can likely help you out. The good...
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    Preemptive Priority scheduling

    Another thing to consider related to being thread-safe. Anything that gets interrupted has to be ok with it and also with other things running in the meantime, including, perhaps another process calling the same code. Two processes might update the state of the same hardware with conflicting...
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    Help with prototype designing

    Oh, yeah. I'd immediately pictured random placement of multiple objects. An assumption that may not have been true.
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    Microwave detection circuit verification

    I'm afraid that that circuit will "physically measure/compute the radiation". . Also ovens are strong sources. This device may not be very sensitive. It may not pick up the "radio-wave" things you wish. . Will these things be a problem?
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    Help with prototype designing

    I read it twice. I have little idea what you want. . What is "surface tension" for a (presumably solid) metal? Is this like high-tension, voltage, potential? No clue why the other metal things would be also connected to <I have no clue what>. If they are metal, they are basically conductors. Do...
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    Calculating an single output from two inputs...maths help!

    I have to say that I find the description confusing. Would love to help, but I just can't quite get what you are asking. I presume this is the aim, for soem reason. . Where is that plane compared to your left-right & up-down? A figure or two, perhaps? . So, nothing to do with the hprizontal...
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    Microwave detection circuit verification

    I've seen toroidal or C-core transformers used where there is an interest to have some greater immunity to outside fields or not create any external field greater than necessary. Is a reason that a toroid the natural shape for the recption antenna, sensor, sprry not so sure what to call that...
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