Despite being from a 1969 publication, the transistors used have current equivalents such as BC548 and BC558. The circuit generates signals from 1 500 to 20 000 Hz and 4 scales.
Avago Technologies (www.avago.com) suggests the circuit in Figure 9 for amplifying signals of...
We found this circuit in a 1986 publication. However, as it is based entirely on 555 integrated...
This circuit can be used to listen for SSB signals on receivers that do not have the built-in...