On Sun, Nov 6, 2016 at 12:50 PM, IVP wrote: > How about a PIC10F with ADC ? Economy vs discretes might > not be too bad in quantity (10F320 ~ NZ$0.70 @ 100) > Hmm - I don't think the price of that would be a problem - realistically the cost of components is likely to be dwarfed by the build costs whichever way we go. It would certainly be straightforward to avoid the oscillation problem which I think would be an issue with most or all of the other proposed circuits. Not really sure why I didn't think of that when posting to a PIC list (though I suspect I'd probably go with an AVR as I have more recent experience of those, so the dev would be a lot quicker). Not that it would reduce the part count much - it would still need a potential divider on the input, something to drop the input voltage within range and an output FET. In answer to some of the queries, current requirement is low - I'd assume less than 100mA because it's for something which would last many hours with a fairly small battery. I'm not sure of the battery chemistry and hence max voltage or quiescent current requirements (though I'm expecting quiescent current not to be a big problem) - the only spec I've been given is a 4.5V cutoff. Will get some more details in order to spec this better. Some more details - it's for an external battery for a tracking device, to be used in an event which lasts up to 7 days - though the battery will get switched over during that, so I'm not sure of the expected duration. Needs to be small, light and simple - I don't think pressing a button to enable it is likely to be a good idea, it needs to be fully automatic when plugged in. Thanks for all the info so far - it seems I wasn't too far off with my initial thoughts, though it's good to get better suggestions. Chris --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .