This circuit is from a manual from the 80's and the operational one used, uncommon nowadays, can be replaced by a modern equivalent. The power supply must be symmetrical.
Published in an old Popular Electronics, this circuit makes use of components that are still...
This modulator circuit for transmitters was found in American documentation from 1964. It can be...
This circuit for frequencies from 1Hz to 100 kHz was found in the June 972 Radio Electronics...