Voltage monitor (CB7947E)

This circuit was obtained in a 90’s Popular Electronics. The operators admit equivalents such as 741 or even comparators such as the LM339.

Amplifier for galvanometer 2 (CB7354E)
Found in a Philips' 1968 documentation, this circuit is slightly different from the previous one. The...
Very low frequency oscillator (CB9042E)
This circuit can generate signals from 1 Hz to 20 Hz in 2 Hz ranges. The table next to the diagram...
Quick Start Siren (CB25765E)
We found this circuit in the October 1994 Electronics Now magazine. The CMOS IC is uncommon these...