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Cake day: June 23rd, 2024

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  • Touch buttons usually work via capacitive coupling: they don’t check for decreased resistance but impedance (AC resistance), which means alternating voltage (often single-polarity, e.g. a 0/5 V square wave, to avoid the need for a negative voltage rail) is applied to them. While conductivity (inverse resistance) allows DC to flow or AC to flow in phase with voltage, capacitive admittance (inverse impedance caused by capacity like a nearby finger) allows only AC to flow, 90° behind sine voltage (proportional to change in voltage, which is 0 for DC voltage). A short to ground is the lowest resistance or impedance possible so if the system just checks for current flow (usually by monitoring voltage drop over a resistor) at any phase, like most touch sensors do, it will see a big current flow (maybe too big for some badly designed ones, so careful!) and register a touch. Some touch sensors use the body’s capacitance to complete an LC or RC circuit, in which case a short won’t work.

    Alternatively, the touch button’s module already contains the touch-detecting electronics powered from DC, and pulling a signal line to ground to indicate touch detection. That requires 3 wires to the button board though and active electronics on it.



  • Look at this anti-communist agitator drawing flags of Austria

    Also, in the Czech Republic, two red lines are used by foresters to mark nature reserves or other areas where logging is restricted, while hiking trails use a single colored line or symbol on white 10x10 cm background, as shown in the photo (except multiple line symbols share the same background, separated by a white line, to save space). Of course, birch, light-colored rock and reverse side of traffic signs (heavy-duty stickers) use a dark green background painted on them to make the white stand out.


  • It’s the lowest-tech device that can do this with sufficiently low running costs to make it free to use. Much better than the more common infrastructure of QR codes and a server of audio files (or worse, app!)

    And there are hiking trails with information panels that have this technology (the button switches narration languages or bonus tracks) for accessibility to the visually impaired built into the post. It does not need to be this big but the tall-human-sized bent pipe is an artwork by itself.










  • ChaoticNeutralCzech@feddit.orgtoScience Memes@mander.xyzNot a single one
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    1 day ago

    Water vapor from the cooling tower is also a greenhouse gas but all heat exchange power plants at such scale emit it, and it condenses quickly (and increases albedo if the cloud is visible). Plus the nuclear waste, if not economical to recycle, may become its own long-term problem too. So the overall externalities of a nuclear power plant are small (it’s the least deadly one!) but not zero.