This protective circuit for power lines was found in a Radio Electronics from November 1957. The transistor used can be any general-purpose transistor such as the CK722.
Found in American documentation from the 1980s, this circuit has a diode feedback. At the exit we...
This circuit was found in a 1985 English magazine, but it can still be easily assembled, as the...
We found this circuit in a 1975 publication. The power supply must be symmetrical, but other...