This circuit that generates signals between 1.5 and 2 kHz was found in a documentation from the 90's. The capacitor C1 can be changed to obtain other frequencies.
The operational amplifier of this balanced circuit is old and can, however, be implemented with...
This SSB modulator does not use the balancer transformer. The circuit is from an 80's...
In the figure we show a configuration for a crystal controlled overtone oscillator using a...