This circuit uses a resonant reed switch at the trigger frequency. The circuit is from General Electric in a 1966 documentation. This type of component is rare today.
The operational amplifier used in this application is not the most common today. The circuit is...
In the figure we have the way to trigger a 7555 CMOS monostable with a positive pulse. The time...
This circuit was found in a 1926 German publication. It is a crystal or galena (D) receiver. The...