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Stand by power WP 34s & HP 35s
09-12-2014, 11:19 PM (This post was last modified: 09-12-2014 11:20 PM by d b.)
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RE: Stand by power WP 34s & HP 35s
(09-12-2014 06:29 PM)abaldoni Wrote:  
(09-09-2014 07:10 PM)pito Wrote:  There is an another design "feature" with hp30b/wp34s/wp31s - the two cr2032 batteries are wired in parallel, without any isolation diodes. It means the "stronger" battery will always discharge itself into the "weaker" one.. And there are none two batteries equal..

Yes, however a diode drop would probably worsen the situation.
I didn't analyze the circuit, but from the behaviour while measuring currents, it seems to me that HP 35s actively switch from one battery to another every couple of seconds while on and idle (but stood on the same while running the loop program). I don't know what's happening in off state, probably it has normal diodes to power the processor enough for waking up and bypass them when on.

Best regards,
(Mr.) Andrea Baldoni
My guess is that if the 34s team had had anything to do with the design of the 30b series then it would have been as perfect as the rest of the 34s is. And: if HP had only known what was going to be made from their "bean counter" calculator then they would have done some things differently.

Sam Kim showed me the ARM version of the 12C when he had Tim's job, back in I think '09. He said that that and the mythical and secret 30b series were things he hoped would be adopted by other manufacturers for other uses. He showed me how they could snap into a larger unit and become the user interface for makers who would rather let that be made by the experts. He knew that I was a surveyor and asked what I would think of a total station or data collector with an HP quality keyboard and screen. I said "dude............sign me up".

That never happened but the 34s did. Lucky in a different way.
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Messages In This Thread
Stand by power WP 34s & HP 35s - abaldoni - 08-28-2014, 10:38 AM
RE: Stand by power WP 34s & HP 35s - pito - 09-09-2014, 07:10 PM
RE: Stand by power WP 34s & HP 35s - pito - 09-09-2014, 07:30 PM
RE: Stand by power WP 34s & HP 35s - d b - 09-12-2014 11:19 PM

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