This circuit was found in a Signetics documentation from the 1980s. The integrated is a PLL and the SCR is a general purpose type The pitch frequency is given by R1 and C1 as formula next to the diagram.
The power transistors of this 80's circuit should have at least 10 A current collector and mounted on...
The critical component of this circuit is the transformar. We found it in an 1980s documentation....
This circuit is from an Italian publication called Fare Elettronica from 1987. What we have is an...