This circuit is from American documentation from 1970. It can be designed with a BC558 and for the operational, we can use equivalents. The FET can be the BF245.
We found this circuit in an old documentation. The indicated solenoid is of low current type,...
This commercial circuit of 3 transistors was found in Japanese documentation from the 1960s. The...
This circuit was found in National Semiconductor documentation from the 90s. The circuit uses two...