This circuit is from a Radio Electronics magazine from May 1986. Observe the voltages applied to the capacitors, taking care that the capacitor under test can withstand them.
Found in the October 1992 Radio Electronics magazine, this oscillator is controlled by switch S1....
This circuit was obtained in a 1976 amateur radio manual. The circuit can be made with a 2N2222...
The component used in this circuit is not very common today as the circuit is from the 80's. It...