Originally suitable for photography applications, this circuit from a Popular Electronics from the 90s can also be used to time plate baths. The components are common, and the sensor is remote.
This is the receiver for the previous circuit we found in the December 1992 Radio Electronics...
We found this configuration with CMOS-compatible output in the 1994 National Semiconductor Linear...
This 70 kHz oscillator is used to erase tapes in pre-recording. The circuit is from 1968 General...