Latching relay (CB25722E)

The figure shows how to connect a relay to obtain the latch effect. The circuit is from an Electronics Now from June 1994.

Biestable Touch Switch (CB10246E)
This circuit is from an English magazine of 1977. The circuit is still current, just using BC547...
Intercom LM384 (CB7033E)
This circuit was obtained in an old Elektor. It is a reference, since the integrated products of the...
Physiological Control (CB19188E)
This circuit was found in a European technical documentation from 1991. It is a circuit that must...