This circuit is from American documentation from the 90s. The transistor is general-purpose and operational amplifiers can be modern equivalents.
July 21, 2015 - Mouser Electronics, Inc. is now shipping the Curiosity Development Board from ...
The circuit shown in the figure is suggested by Micrel, based on the MIC2570 boost voltage...
This sound relay, Vox or acoustic switch has a bistable action triggering a relay when the...