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  1. S

    Charging Lithium Batteries—rather Balanced and in Series or Parallel?

    You're correct in saying that the voltage of the three cells would be the same at all times, but you're mistaken about the current - if you charge three cells in parallel at 6 amps then it doesn't automatically follow that each cell will receive 2 amps. Far from it actually - the current flow...
  2. S

    ZXSC300 0.8v-4.5V 700mA 3W LED Driver - help with componets

    Could you clarify what type of cells you intend to use for this - primary (non-rechargeable) or secondary (rechargeable) and what type - e.g. alkaline, NiMH, or something else? If you're intending to use either Nicad or NiMH then they would be damaged by allowing a series string of three to...
  3. S

    Help for a retired boilermaker

    Just thinking, with half an amp of current flow, the diodes would be dropping closer to 0.9 volts each so I'd only use four in series, which would limit the voltage to about 3.6 volts. I'd still use a 3.3 ohm resistor, which would then pass a current of 1.1 amps with a power dissipation of 3.9...
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    Help for a retired boilermaker

    I would rig up a dummy load. From the datasheet, the XP-G has a maximum current rating of 1.5 amps so I'd make the load to be capable of carrying that current. The driver module's output stage is expecting the voltage to be limited by the LED to around 3.5 volts, so I'd use five diodes from the...
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    Flasher - How to detect loss of brightness

    If the manufacturer of either the light or the driver released a detailed datasheet then the information might be found on there, but in the absence of that then the only practical way to determine run-time in blink mode would be to measure the on/off time durations using an oscilloscope, either...
  6. S

    Little help with ZXLD381 boost driver

    We have light - well done! :goodjob: That sure is a compact circuit, eh. If you draw 30mA from the alkaline cell and only get 15mA at the LED, that might sound like a raw deal, but remember that you're feeding that 15mA to the LED at more than double the input voltage. To calculate the...
  7. S

    Little help with ZXLD381 boost driver

    For the capacitor, I'd say any value between 0.47uF and 10uF would be fine. This is the calculation for ripple voltage (dV) using 0.47uF: dV = I x dt / C = 50 x 10^-3 x 2.05 x 10^-6 / 0.47x 10^-6 = 0.1025 x 10^-6 / 0.47x 10^-6 = 0.218 dV = 0.218V (218mV or 218 x 10^-3 V) If you want to...
  8. S

    Little help with ZXLD381 boost driver

    I think the timings must vary considerably depending on inductor value, so you can't really take the timings from the 4.7uH circuit and slot them into the equation for a different value of inductor, and you've demonstrated that by putting the 4.7uH timings into the 10uH circuit and obtaining a...
  9. S

    New 9v Goofy Light

    Wow, LSDs in a dollar store? Just out of curiosity, do you know what the capacity is? Edit: Ah, I misread your post - they aren't actually in the dollar store (yet!)
  10. S

    iCharger 106B+ 2x18650 series sudden current climb

    I don't know anything at all about that charger, but looking at the green current trace, it doesn't just increase at the eight or nine minute mark, but rather it appears to fall suddenly first, and then it rises dramatically a moment later. Is the mains power stable in your part of the country...
  11. S

    Little help with ZXLD381 boost driver

    It is indeed a formula to calculate the capacitance required to reduce ripple following rectification, so it would often be used at much lower frequencies - 50Hz for half-wave here in the UK, or 100Hz for the more common full-wave (60Hz/120Hz in the USA). The datasheet states the nominal...
  12. S

    Battery charger workaround-dangerous?

    It's a far from satisfactory charger anyway, because it mostly charges above 0.1C with no termination, relying on user intervention to terminate the charge in accordance with the time periods stated in the user manual, based on cell type and nominal capacity - and of course that assumes fully...
  13. S

    Little help with ZXLD381 boost driver

    Are you still going ahead with this one or have you moved on to a 'plan B'? Or did you just go ahead and order the components anyway? The links to the inductors don't work, if you want to try re-posting them, or maybe quote the manufacturer and part numbers and we can find them that way. There...
  14. S

    Good cheap CREE light for DIY practice

    If you want to get a good understanding of drivers then there's an excellent article by HKJ in this thread: Drivers, LEDs & batteries. Also of interest would be wquiles' equally excellent thread: Introduction to modifying flashlights.
  15. S

    Need advice for a 9AA configuration

    No, you can't configure nine cells in that way - the series string of six cells will dump a high charge current into the parallel string of three, severely overcharging them, and if left connected for long enough, the weakest cell in the six-string would drain and then start to reverse its...
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