This double tone generator uses a specific integrated circuit, having been found in a 1977 CMOS Cookbook. The transistors can be the BC548.
This circuit is from an Electronics Now, American magazine from December 1992. The magazine no...
We found this circuit in a 1983 English magazine, but it can be easily assembled with the BC548...
This simple alarm circuit was found in a 1998 documentation. When the sensors are activated, the...