This 80's Exar circuit has a carrier detector for frequencies up to 500 kHz. The circuit uses a company 567 which is still a common component.
We found this circuit in an old documentation, but the components used offer no difficulty in obtaining...
This project was found in a 1982 publication. It is a small transmitter that can send signals from...
The circuit in the figure can be used to trigger a triac or even a comparator in a project that...