This circuit is from American documentation from the 1980s. The circuit can make use of any common NPN transistor and the power comes from two small batteries.
Found in a 1970 documentation, this SCR bistable can be implemented with modern equivalent SCRs. Observe...
This circuit must have its input connected to the collector of the last IF transistor of the FM...
Found in a 90s Electronic Design, this suggestion to have a higher voltage in a fixed regulator...