This circuit was found in documentation for radio amateurs of the 1980s. This is the so-called roger-beep, which is the beep that is transmitted when the talk-listen function is changed.
This circuit is based on an old Siemens integrated that can now be found very easily. It allows the...
This circuit, which operates between 7 and 30 MHz, was found in Radio Electronics from the 1980s....
Found in a 1960s RCA documentation, this circuit applies to most common triacs. The trigger device is a...