This double tone generator uses a specific integrated circuit, having been found in a 1977 CMOS Cookbook. The transistors can be the BC548.
The purpose of this regulator is to regulate the RMS voltage in an alternating current load. The...
Using a 4017 as a base, this circuit from a 1990s Popular Electronics generates low-frequency...
We found this circuit in a Radio Electronics magazine from April 1988; The output timing is given...