This circuit is from an 80's technical newsletter. The circuit can use any general purpose transistor and its power supply can be changed with a resistive divider to use a single 9V battery.
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...