HP Forum Archive 21

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USB Chargers for HP calcs Message #1 Posted by Matt Agajanian on 15 Aug 2013, 11:37 p.m. Hello all. I recall that USB chargers for Classic Series HP calcs were available. Are there USB Chargers for Woodstock and Spice series models available?

Re: USB Chargers for HP calcs Message #2 Posted by Mike T. on 18 Aug 2013, 5:33 a.m., in response to message #1 by Matt Agajanian From the information on this page the output from the chargers for the Woodstock series is 10vac and the output from the Spice series charger is 9vac. USB only provides 5vdc, I don't know enough about the internals of the calculators to know if this would be enough, but I suspect it isn't. Mike T.

Re: USB Chargers for HP calcs Message #3 Posted by Matt Agajanian on 18 Aug 2013, 6:13 p.m., in response to message #2 by Mike T. Okay, that makes sense.

Re: USB Chargers for HP calcs Message #4 Posted by Craig Ruff on 18 Aug 2013, 10:58 p.m., in response to message #2 by Mike T. Quote: USB only provides 5vdc, I don't know enough about the internals of the calculators to know if this would be enough, but I suspect it isn't. If the total wattage required is not higher than that provided by the USB port, the 5 volts can be raised to a higher voltage with a switching converter, with a proportional reduction in the current. This is the same mechanism a camera flash uses to generate several hundred volts from, perhaps, 6 V of alkaline batteries, or even the internal power supplies of several older HP calculator families.

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