This circuit can be adjusted between 0.2 and 2 V to trigger with chosen voltages comparing them with the input voltages. We found it in a 1967 documentation.
We found this circuit in a Radio Electronics of the 90s. The integrated circuit used is not common...
Any operational amplifier can be used in this circuit. The 741 is the most common. Power supply must...
This simple low power stage with output transformer was found in an American documentation. The transistor...