HP-21 Circuit Diagram Schematic

[Gordon Dyer]

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.

http://www.cs.ubc.ca/~hilpert/eec/

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

[Gordon Dyer]

Was anyone interested?

I would like to know if it is accurate.

[Vieira, Luiz C. (Brazil)]

... 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

[Ellis Easley]

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.

[Vieira, Luiz C. (Brazil)]

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