Found in 1980s Electronics Design, this circuit covers 4 decades of frequencies with a unique control. A multi-turn trimpot is used for fine adjustment. The frequency range depends on C1.
This oscillator with crystal for overtone operation was found in an old American documentation. The coil...
This test consists of a simple Hartley oscillator using a transformer of the type found on older...
We found this circuit in an American 1980s documentation. The transistors can be equivalent as BC548...