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.
This circuit was found in documentation from the 80s. The components are from the time, but the...
This circuit is from Philips' 70s documentation. Transistors can be replaced by modern...
This circuit was found in a 2006 publication. It uses discrete components and CMOS that are still...