Found in American documentation, this switch is based on the 4093. The load will determine the supply voltage. The transistor is general purpose.
According to the author of this project, from a documentation on espionage from the 1980s, this...
This circuit suggested by Siemens can provide time intervals for triggering values that are given...
This circuit generates a good-intensity 1 kHz rectangular signal. The circuit is from Electronics Now...