This circuit was found in a 1969 Mullard publication. The transistor may be the modern equivalent of BC548. Observe the relatively high supply voltage.
When the sensor connected to points A and B is activated, removing the ground from the base of Q1...
This oscillator was found in the 1994 National Instruments Linear Applications Handbook. The...
With the circuit shown in the figure, the frequency of a 5 MHz oscillator controlled by crystal can...