This circuit is from an 80's technical newsletter. The circuit can use any general purpose transistor and its power supply can be changed with a resistive divider to use a single 9V battery.
This audio oscillator configuration appears in many of our circuits and even in this section from...
Found in an American documentation from 1992, this circuit for medium and short waves uses a CI of...
Measuring capacitances and resistance this simple instrument was found in Radio Electronics...