This circuit was found in an Australian publication from 1991. The circuit emits a tone as well as the picked up sound when triggered.
This circuit was found in an Analog Devices publication from the 1990s. The circuit performs input...
Found in Motorola documentation from the 90s, this circuit can be implemented with current...
We found this circuit in an old documentation for hams. In it we have the way to use a varicap to...