This circuit was found I a 1965 Radio Schack documentation. The transistors are from that time, admitting equivalents. The transformer has 500 ohm primary and secondary depending on the speaker.
This circuit is a variation of the common grid dip meter, having been found in a 1975 publication on FETs....
We found this circuit in an old American documentation for hams. The circuit serves as a telegraph...
This is a very simple configuration with a power transistor to control a DC motor from 3 to 12 V...