HP-97 on charger only

[teenix]

(04-18-2020 08:12 PM)aurelio Wrote:  here attached a pic

One problem with that setup is the voltage applied to the calculator will be the RMS value of the AC transformer output minus diode drops from the rectifier bridge, not the intended 5V from the battery. Depending on the transformer used, it is possible that the overvoltage circuit is working to a degree to trim excess voltage back to avoid circuit damage. If the transformer is a low current type like the charger, then it probably wont reliably supply power for the printer and maybe the card reader.

cheers

Tony