This circuit was suggested by Motorola in a 1969 publication. It makes use of components of the time, but both the FET and the bipolar may be general purpose current types.
This frequency shift modulation circuit was found in the November 1994 issue of Electronics Now...
August 2017 - Mouser Electronics is stocking the new Molex optical EMI shielding adapters. These...
This traditional configuration with the 555 was obtained in an 80s Hands-On Electronics. The relay...