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.
The circuit shown in figure 5 generates square signals based on a transconductance operational amplifier...
By adding a transistor to the output and some polarization features we can obtain a higher output...
Found in the 1990 special issue of Radio Electronics Experimenter magazine, this circuit uses an...