Read?Write HP 67 card reader

[AnnoyedOne]

(10-05-2024 09:29 PM)teenix Wrote:  DC motors can also generate a nasty negative spike when switched off, but this might be handled by the sense IC.

Yeah. Anything inductive (DC motors, relays, etc.) generates "back EMF" when the current flow ceases. Usually limited by a diode (reversed) across the coil. There could be one in the IC.

Quote:Low ESR tantalums might be of use here, I don't know if the originals were.

I don't think they existed in the mid-1970's. They shouldn't hurt anything, if used, though.

A1