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  1. dave9

    Remington Shaver HC6550 not to full Power

    Can you measure battery voltage at the charging contacts (if it has any that are accessible)? If so then compare full charge voltage to the voltage at the point of shutdown. It might just be a dying battery. How old is it? If you have no external measurement points then you have to open it...
  2. dave9

    Please help a lay person with some repair questions

    Also I know nothing of how advanced the circuitry is in any particular massage chair, but it seems like on better designed models, if there is no travel limiter sensor/switch (if there is, then check those), then there might be fusible circuits for each motor so check fuses... thinking maybe...
  3. dave9

    Please help a lay person with some repair questions

    Basic diagnosis might involve checking for resistance across the switch contacts when pressed, examining the PCB for stress cracks, measuring for where in the circuit the power stops. Once you determine the fault, then determine whether a discrete component can be replaced, or a motor (might...
  4. dave9

    Who's right and who's wrong?

    Maybe you cannot use a switch to limit current. I can, and so can BMS designers. That's not our problem. Again, semantics. You want to pretend that current limiting needs to mean "constant current", when it does not. Anyone with the ability to use a full vocabulary would use the word...
  5. dave9

    Who's right and who's wrong?

    You fail to accept that "limiting" can be binary. This is limiting you from seeing the other side of the argument. ;)
  6. dave9

    Who's right and who's wrong?

    You guys aren't wearing a mask?! I'm staying 6 feet away from my monitor from now on.
  7. dave9

    Led chip appropriate resistor

    How much space do you have available? A single series resistor (better two, one for each headlight LED) may be the smallest in volume, but far more efficient would be a current regulating LED driver (with minimum value balancing resistors in series to each LED), or two current regulating LED...
  8. dave9

    Who's right and who's wrong?

    Semantics. BMS often limit current to the extent that there is a variable upper limit, for example when a temperature sensor reaches its set point, to prevent overheating. Switching off the cell is implied to be current limiting because it is usually excess current ( multiplied by duration...
  9. dave9

    I would like to power a table radio with 12V DC instead of 110V AC

    ^ I'd still want a low voltage cutoff circuit to not excessively drain the battery.
  10. dave9

    I would like to power a table radio with 12V DC instead of 110V AC

    ^ I've added more to my prior post. I can't predict the minimum voltage the radio needs to operate correctly but it is bound to also be a factor of how loud you want the sound playing. I mean it would probably work fine down at 8V and even lower, considering it must do this to get reasonable...
  11. dave9

    I would like to power a table radio with 12V DC instead of 110V AC

    ^ Yes that is the point of a regulation circuit, though once the battery drops below a certain voltage, the forward drop of the regulator (suppose around 2V) will stop stable operation. For example with a 12.6V battery and a 2V forward drop, it should be stable down to at least 11V with the...
  12. dave9

    I would like to power a table radio with 12V DC instead of 110V AC

    There are lots of buck converters capable of more than 18W. 18W might even be enough, but it's always nice to have more margin, especially if it's a generic chinese module with optimistic ratings which don't correlate with the minimal heatsinking they provide on a tiny PCB. One example...
  13. dave9

    Help needed with portable car battery charger

    Whoever you find to do the repair, is more likely to be able to diagnose it too since they have hands on it. It will probably cost as much or more for the repair than it is worth... something like that (same capacity) I can find on Amazon (US) for about $65... but if the design is prone to...
  14. dave9

    Help needed with portable car battery charger

    Okay, a non-latching switch.... still have to open it up to see what's what. Over the years I've collected spare, random/junk screwdrivers. If I didn't have a triangle drive type, I'd turn one into that on a bench grinder... grind a bit, check it for fit in the screw head, grind some more. A...
  15. dave9

    Help needed with portable car battery charger

    There is no risk of "shock" (bodily) harm, because it is only ~16.8V or so, fully charged. It's the voltage that causes X amount of current to flow. It can instead deliver a lot of current, so don't accidentally short it out with metal tools, which could cause a spark, or melt/pop a...
  16. dave9

    How to power one or two of these clusters

    ^ Solve it similarly. ;)
  17. dave9

    The best brands of drivers for LED lights

    That is still very vague. Typically you focus on ONE specific integrated product, then the PSU is designed for it, or in other words offered from the same supplier. If you are instead designing your own, then you need to consider what that design needs.
  18. dave9

    The best brands of drivers for LED lights

    The question seems a bit vague since there are many configurations possible to make a light out of LEDs. What are you trying to drive?
  19. dave9

    Towards 6G Internet of Things

    Are you a human? That looks more like a bot post. And it's nonsense. The (n)G standards will continue to evolve as the data requirements increase, yet any smart app that can't get by with 5G is poorly designed since that is the standard for the market. Besides, 6G is kind of arbitrary, why not...
  20. dave9

    Replacement pcb mount nicd battery

    You could measure the voltage and current to it to see what the charging circuit is doing (with a high ohm resistor load). Depends on the device, but a common NiCd stack of that capacity, would be trickle charged off 5V rail with a current limiting resistor in series, or whatever > ~4.4V rail...
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