This circuit takes advantage of the hysteresis of a relay to provide a latching effect. The circuit acts as a trigger and the components must be according to the used relay.
Found in a Maxim documentation from the 1990s, this current-sensing amplifier uses components from the...
We found this circuit in a 1982 documentation. An intercom to be good must be sensitive and have...
This circuit is from a 1980s documentation, but the configuration can be applied to most modern...