Recent content by guyburns

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    Suggestions for headlamp – further questions re Petzl's Actik

    Thanks for all the responses. Looking into all the suggestions, the choice came down to either the Petzl Actik Core or the Black Diamond Spot 350. The decision was made for me when the Spot 350 was half price at Black Diamond (Australia) for $40. So I bought the last two. Great light – except...
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    Suggestions for headlamp – further questions re Petzl's Actik

    After a few hours of reading manuals I came across this in the User Manual for the Actik Core: WARNING: if using the CORE battery, when the battery is nearly drained, the light may turn off abruptly. Ques 1 This abrupt turn off when using the CORE battery, does that occur… • ONLY after I...
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    Suggestions for headlamp – further questions re Petzl's Actik

    So it looks like one of the Petzls: Tikka, Tactikka, Tikkina, or Actik, with the latter being the most promising.
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    Suggestions for headlamp – further questions re Petzl's Actik

    Thanks for the suggestions. The Nitecore UT27 was top of my list, until I read this review about broken hinges (see Final Verdict at bottom). Maybe just a once off, but broken hinges put me off. The Fenix suggestions led me to their website and the HP16R, their only headlamp that fits my...
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    Suggestions for headlamp – further questions re Petzl's Actik

    I'm having difficulty locating a suitable headlamp. I have three ZebraLights, some dating back ten years, and they work superbly – but they don't have a red light, which I sometimes require to retain night vision. So, last time I was out at night I took my Energizer (see similar, here). It just...
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    Suggestions on how to replace projector bulb with an LED

    Thanks for the responses. I wasn't really thinking of using an LED torch, but a stand alone LED with a focussing lens and a driver • Colour temperature or CRI is not important as this is for editing (and subsequent scanning) of B&W films. • High power is not important. Most editors use a 10...
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    Suggestions on how to replace projector bulb with an LED

    Background I have 10,500 ft (7 hours) of old 9.5mm film to go through. I'd like a proper viewer, but they're extremely rare in Australia. A film viewer is like a slide viewer – uses a low wattage bulb to show a small image. Instead of a viewer, I want to: use a 9.5 mm projector replace the...
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    Can a li-ion cell be overcharged at a lower than normal final voltage?

    Some results from my testing: charging a 1200 mAh, 7.2 volts cell to various voltages, with charging terminating at a current less than 2 mA, well below the normal cutoff current of ~0.03C. Voltages given are per cell, and the capacity figures are the average of three runs. When charged with the...
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    Can a li-ion cell be overcharged at a lower than normal final voltage?

    I have just tested a dedicated charger for a 7.2 volt Li-ion cell for a Lumix GH2 camera. A cheap 3rd-party battery and charger from China. The battery is labelled as 1200 mAh, but after seven charge-discharge cycles its actual capacity averaged out at 840 mAH. The charger has interesting...
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    Can a li-ion cell be overcharged at a lower than normal final voltage?

    I assumed the same – that the cell won't like being left charging at a lower-than-normal voltage. What confuses me though is: if that website I linked to is correct, how can you overcharge a cell that can supposedly never reach full charge?
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    Can a li-ion cell be overcharged at a lower than normal final voltage?

    I want to find out if a LiFePo4 cell (or any li-ion cell) can be overcharged, and thus suffer damage, if the final constant-voltage portion of the charging (called the "saturation charge") is done at a lower voltage than normal. A typical charge regime for li-ion will be constant current until...
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    Battery power in the wild – suggestions wanted

    Thanks Mark for reiterating your suggestion. Keep them coming. I've looked into it, and LiFePO4 batteries are looking good. The only problem with the 12-volt packs would be the reduced power out of the solar panel. Four cells in series would require 15.2 volts at termination (3.8 volts per...
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    Battery power in the wild – suggestions wanted

    I can't claim it as my definition; V x I x t is how you calculate electrical energy. The smaller you make the time increments, the more accurate the answer is. And you are partly correct about a Joule being the same as Watt-hours and kW-hrs: Watt-hr = 3600 J kW-hr = 3.6 MJ It's also similar to...
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    Battery power in the wild – suggestions wanted

    Applies to a wide variety of phenomena, and partly explains why increasing your speed in a car uses more petrol/distance. Even though you get there quicker, you use more petrol to overcome the wind and other resistances (probably square law losses). Good on y'mate, for doing the calculations...
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    Battery power in the wild – suggestions wanted

    I want to make myself clear about what I am doing. I have no barrow to push. If certain of my ideas about batteries/chargers are incorrect, and you can point me to authoritative sources that prove I am incorrect, that's great. I'm here to learn about batteries. I would ask the same in return. It...
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