Right. And when you're bouncing along a bush track in the back of a 4x4, trying to navigate on paper maps using the light of a head-torch during a hidden-transmitter hunt, and you need to change 3 AAA batteries in the round cartridge, you have to get all three right and do it *now*... while juggling the torch, the maps, the cartridge, the old batteries, the new batteries... well, you can see why it's easier just to take a spare head-torch ;-)
But this tech would often be a help, and personally I'd pay a little extra for it!
I was thinking along similar lines albeit BJTs rather than MOSFETs
- it is not for nothing than MOSFETs are often drawn with a parasitic reverse biased diode.
I've actually done this kind of thing using BJTs in the past although the intent there was to reduce heat dissipation rather than voltage drop although that pretty much means the same thing at the end of the day. The drop is reduced to two collector-emitter losses.
You do need to watch the voltage though since my experience is that BJTs can breakdown far faster than you might expect when reverse biased. However that is unlikely to be a problem for battery powered equipment particularly when you are having one circuit per cell as here.
Actually, thinking about that I'll have to go through it and see if the system I used would actually work in that arrangement. It's just possible the other cells could interfere with the biasing and I don't have a schematic in front of me to consider that possibility.
Yes, even when it's designed right in from the start. Do you want to change the habit of a lifetime and start _justifying_ your pronouncements instead of simply endlessly repeating them as if that alone is enough to make them true?
Yes, even when it's designed into the device right at the start. Not that it really matters, this kind of circuitry is basically invisible to the rest of the system aside from any voltage drop. You can put it in at the start or before laying out the final production board - it doesn't make that much difference
Yes, even when it's designed into the device right at the start.
Because a cost/benefit analysis (however informal) shows that LED is worth including. It's a standard design trade off, cost vs. functionality. For some devices, those indicator LEDs are the _only_ sign of life that is not dependent on connected equipment.
It was more of a proof than simply spouting "not when it's designed in right at the start" in parrot-like fashion. The way I'd do this would use four transistors and four resistors, plus a bit of board space, extra soldering, possibly extra drilling, more faults etc. I don't see it costing much less than about 8p even with a reasonable production run. For some sectors that is unacceptable even on equipment going for three figures. If the device is supposed to sell for a fiver it is unacceptable anywhere.
So, the 99.9+% of designs (including, for example, most computer motherboards) that use no custom ASICs are a complete irrelevence, are they?
Adding _power_ transistors to your typical ASIC will certianly not be free. I suspect you would be looking long and hard for a foundry to even entertain the idea. It is competely impossible with the sea of gates ASICs for a start.
It was your assertion that when it is designed in is somehow pivotal to how much it costs. If you had continued to read the very sentence you truncated you would have seen that _that_ makes no real difference.
The user is accustomed to ensuring battery polarities are correct. How many devices out there have this kind of any-way-will-do circuitry? If there was a massive demand for it it would have been addressed long ago.
No, of course it wouldn't cost anything like that. Instead it would probably be at least a capital cost of £100,000 for the ASIC and another £1 per unit to accommodate those on chip power transistors.
I already have. You chose to invent a new economic reality instead of reading it. Now I remember why you were in my killfile.
Not in an emergency situation for instance where you just need to replace the batteries as fast as possible and you might be under some stress in a less than ideal environment. Not everyone replaces batteries whilst sitting at their desk sipping a caffe latte :->
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