This circuit is from a Radio Electronics magazine from July 1979. It uses the well-known IC 7107, a liquid crystal exciter that became popular in circuits of this type at the time.
This is the basic operational amplifier configuration for gain 10. R2 can be changed to other...
This circuit uses a capacitor that depends on the frequency of the crystal. We found it in a 1967...
The crystal frequency of this circuit found in an American documentation is limited only by the...