This circuit can generate signals of crystal multiple frequencies. The resonant circuit must be according to the desired frequency. The transistor must match the frequency.
This circuit is from 1997 documentation, based on the well-known integrated circuit 555 and 4017....
This circuit is from 1980 documentation. We can exchange the BC177 for a BC557 and the TIP41 must...
From different input voltages V, it is possible to reduce the voltage to several fixed values...