Recent content by noname12345

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    Help requested with translating math into code (Not homework)

    Too late. The poisonous effect of premature and incorrect redirection persists and will prevent anyone bothering to consider the actual question. If I could delete it I would. I I could delete my account, I would. But as this place is still living in the old days, I have to settle for...
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    Help requested with translating math into code (Not homework)

    There is no gear cutting machine involved. The code in question is for generating gear models for use in FEA simulations ONLY. That book -- a (very old) copy of which is on my bookshelf -- has nothing on differential geometry. It is only the math -- particularly the differential geometry math...
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    Help requested with translating math into code (Not homework)

    The paper is https://core.ac.uk/display/10365043 (12MB pdf) My purpose is to construct parametised spiral bevel gears (using OpenSCAD). I know how to produce a correctly formed circular cut (cylindrical) crown gear profile. My problem is mapping that to a conical surface. I am looking for...
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    Pool Ball Physics: Questions on Impact Spins

    Can I take that you are suggesting that if (say) the cue ball has spin around its vertical axis at the moment it hits the object ball; some portion of that spin will be transferred to the object ball (presumable in the opposite rotation like meshing gears) during that brief moment of contact...
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    Pool Ball Physics: Questions on Impact Spins

    I'm aware of (and can do IRL) swerve & masse shot by applying spin (English) to the cue ball when you strike it; but despite that I used the cue ball in the demo above, (its much easier to capture) no spin was applied. Also, if you look closely, the ball's path from the strike to the first...
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    Pool Ball Physics: Questions on Impact Spins

    1) Can the contact between two pool balls impart any kind of spin, other that about its horizontal axis due friction contact with the table surface? 2) If a ball is in motion (traveling in a straight line) and contacts a cushion, can that contact impart spin to the ball such that when leaving...
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    Electrical Unconnected wall wart power consumption

    You got me walking round the house putting my hands on all the devices trying to detect heat :) So far, the only one that is detectably warn to touch is my ancient rechargeable shaver. May be time for a new one.
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    Electrical Unconnected wall wart power consumption

    Hm. If the battery is flat. It's off! And a 15y/o computer is neither a wall wart nor a fast charger. And USB plugs used for charging often (if not always) only have the power pins connected. No communication is possible. Main draws in my house -- in roughly the order of consumption most to...
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    Electrical Unconnected wall wart power consumption

    Ooo-kay. But... :) Reactance results from self-inductance. And inductance is due to a change (ie. rise or fall) of voltage... I think this (from: https://en.wikipedia.org/wiki/Electrical_reactance) explains what you are saying: "Reactance is similar to electric resistance in this respect, but...
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    Electrical Unconnected wall wart power consumption

    Okay. I read the wiki article (and several others linked from it); this is what I think I got from it: Because the primary coil is reactive as well as resistive, the current flow lags the (AC) voltage rise and fall. And because both voltage and current keep reversing, the net current flow over...
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    Electrical Unconnected wall wart power consumption

    Thanks. That reassures me about most of the modern devices with SMPSs. I still need to understand the costs of the older devices with mains frequency transformers. My understanding of leaves something to be desired. As far as I know, "quadrature" simply means the secondary is 90° out of...
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    Electrical Unconnected wall wart power consumption

    Indeed. I was wandering around my house looking at all the devices that use wall warts and are designed to be plugged in permanently: Including: cordless vac; shavers; toothbrushes; hairclippers; PVRs; TV sticks; cordless phones; wifi hub; wifi extenders; LED desk lamp; LED monitors; alarm...
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    Electrical Unconnected wall wart power consumption

    Wouldn't that mean it couldn't be charged if powered off; and letting your battery get completely flat would effectively brick it?
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    Electrical Unconnected wall wart power consumption

    I've been assuming that any circuitry would be limited to a diode bridge and RC smoothing stage connected on the secondary side and thus open circuit when nothing is connected. Now you got me wondering who my wall warts are talking to and what they are saying about me :) That's really...
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