This circuit is from a 1969 Electronics World. The transistors may be modern general-purpose equivalents. The circuit is for frequency ranges between 250 Hz and 250 kHz.
The Variable Frequency Oscillator (VFO) shown in the figure can generate signals in a frequency...
This circuit was obtained from a 90s Radio Electronics. The integrated circuit used HAA11508 is not...
This circuit was found in a 1980s American schematic. Transistors can be modern equivalents. The...