This simple low power triplicator was found in 90’s American documentation. The diodes can be general purpose types and the frequency is determined by the RC network of the 555.
This xenon lamp circuit is from old documentation. The trip transformer has a 1: 1 turn ratio and...
This simple alarm with integrated CMOS sounds a piezoelectric transducer when the sensor circuit...
In the figure we have an interesting circuit for those with a project that requires a sub-multiple...