Found in a European magazine from the 90s, this circuit emits beeps that are several seconds apart to indicate that a device is on. The transducer is a ceramic or crystal capsule.
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,...