This circuit is from an old documentation, making use of an operational of the time. The circuit can be adapted to use modern components. The power supply must be symmetrical.
This circuit with integrated TTL 7400 has a good teaching purpose, drawing one of two LEDs. The...
Found in American documentation from the 70s, this circuit uses components of the time, uncommon...
This circuit makes use of a diac to stop the activation of a sensitive reed relay 1 mA. The trip...