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.
This circuit is from an English book from the 1980s. Transistors can be general-purpose types of...
This circuit from the 80's can be easily implemented but needs some changes to avoid problems with...
The presented circuit provides an output voltage proportional to the input current, according to...