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.
This circuit can send signals in both the VHF and FMN bands with a range of a few tens of meters. The...
Found in a 1960 Sylvania transistor manual, this circuit can be implemented with modern...
August 2017 - Mouser Electronics already has in stock the new integrated circuit CP2615, which...