This simple sensitive circuit was suggested in a July 1992 Radio Electronics issue. The relay is a double-contact changeover relay. Sensitivity adjustment is made at R2.
This VCO with a common operational amplifier was found in an old American documentation. The...
This circuit is from a Radio Electronics magazine from May 1989. The power supply must be...
August 2017 - Mouser Electronics is making STMicroelectronics' Analog and Digital MEMs available in a...