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HP-21 Circuit Diagram Schematic - Printable Version

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HP-21 Circuit Diagram Schematic - Gordon Dyer - 05-12-2003

I have found a circuit diagram for the HP-21. I don't know if it is accurate but it is worth a look if you are interested.


Click on the calculators link at the top of the page, then click the HP21 link and then click TD23 Data: view

That should get you to hp21.gif

Re: Any Intewrest? HP-21 Circuit Diagram Schematic - Gordon Dyer - 05-13-2003

Was anyone interested?

I would like to know if it is accurate.

I downloaded it... - Vieira, Luiz C. (Brazil) - 05-13-2003

... but missed the "Thank you" share. It's been quite noisy, busy morning here...

Thank you, Gordon; there are other good sources there.

Best regards.

Luiz C. Vieira - Brazil

Re: I downloaded it... - Ellis Easley - 05-13-2003

Yes, thanks Gordon! I'm going to ohm out the common portions of my HP25 and then maybe I'll figure out a way to add the additional chips to the schematic.

It's the same one I was sent from another contributor - Vieira, Luiz C. (Brazil) - 05-14-2003

Hi, Gordon;

I opened the file and I saw the additional circuit to suppress batteries when using external AC Adapter. It's the same one I was sent form another contributor. I know who is he, of course (thank you, R.) but I keep my policy of never mentioning a name associated to particular gestures before asking for permission. I know you all understand that.

But I was not aware about where did it come from, and now you, Gordon, have opened the box.

Thank you very much.

Best regards.

Luiz C. Vieira - Brazil