USB Chargers for HP calcs

[Matt Agajanian]

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?

[Mike T.]

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.

[Matt Agajanian]

Okay, that makes sense.

[Craig Ruff]

Quote:

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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.

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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.