This circuit was found in a 1980s American documentation. The circuit is based on integrated CMOS 4001 that are common today. The load is a relay according to the power supply from 6 to 12 V.
This circuit for PC and which can also be used with microcontrollers was found in an English...
This two-tone decoder has a bandwidth of 24%. The circuit is from a 1994 Electronics Now. The...
The LMV321 is a low voltage operational amplifier from ON Semiconductor. The following diagram,...