This circuit can generate signals of different frequencies, switched by a DC voltage. The frequencies are determined by the crystals. The circuit is from a 90s American documentation.
This circuit fires by burning the fuse when the input voltage exceeds the value referenced by the zener....
The UAA180 integrated circuit is no longer manufactured, but if the reader finds one in a scrap...
We find this circuit in a Radio Electronics of July 1984. It consists of the traditional version of 1 A...