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 based on a regulator component that consists of a transistor and zener in the same...
We found this conventional circuit with the 555 in a documentation from the 70s. Several similar or...
This amplifier with gain control was obtained in a documentation from Signetics of the 80's....